Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
80's vintage German printing equipment (offset press industry) uses a video
plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? Thanks. |
#2
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
DaveC wrote:
80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? Put in ANY frequency, as long as it is known. Fire the gear up, and observe the video output with a scope. measure the horizontal sync frequency. Now, you can easily figure the ratio (up or down) to get the desired H sweep freq, and most simple monitors should sync to it, even if the number of vertical lines is a bit off. Jon |
#3
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"DaveC" wrote in message ... 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? Thanks. Can you feed in a test signal from a signal generator and see what you get on the display? A line in NTSC is about 64 us. If you have 80 characters x 7 dots, that's 560 dots per line or about 0.114 us per dot. That gives about a 9 MHz clock frequency. Maybe you can find a good signal generator and start out in that range. At least it would give you a clue as to what the video format should be. |
#4
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Followups set to sci.electronics.repair .
In sci.electronics.components DaveC wrote: The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. Suggestion: Identify the "output" of the LS04, remove the LS04, hook up a function generator to the "output" trace, and start turning the knob. At some point, something resembling video should start coming out of the output. Continue turning the knob until the period on the video is correct. At a guess, the answer is probably somewhere between 1 and 20 MHz. Another way to do it: Grab the first random crystal between 1 and 20 MHz you can find and solder it in. Look at the video output with a scope. You will probably see something resembling either PAL or NTSC video; compare the period of what you see to the standard, and change frequency accordingly. An analog color TV will have a 3.579545 MHz crystal in it. An old PC motherboard (286 and below) will probably have a couple of crystals on it; one is often 14.31818 MHz. http://en.wikipedia.org/wiki/Crystal...or_frequencies lists some common PAL and NTSC crystal frequencies. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." The "AC Characteristics" section gives the minimum CCLK period as 480 ns, which is 2.08 MHz. That doesn't mean you need a 2 MHz crystal max; CCLK is one-eighth of the dot clock, so the crystal would be 16 Mhz max. From the block diagrams on the data sheet, if the parallel bus on the LS96 you found is hooked up to a couple of ROMs, then the clock input to the LS96 is probably the dot clock. Matt Roberds |
#5
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
DaveC wrote: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape ? size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? Mono video used 15,750 Hz for horizontal sweep. NTSC video used 15,734.34 HZ for horizontal sweep, and was often derived from a 4X colorburst crystal at 14.318180 MHZ by dividing by 910. The same ratio would need 14.332500 MHz for Mono. Can't you find an old XT monochrome video card for reference? |
#6
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Michael A. Terrell schrieb:
80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... What frequency crystal should I be looking for? Mono video used 15,750 Hz for horizontal sweep. In Europe, especially Germany, horizontal frequency was 15.625 kHz and vertical frequency 50 Hz in those days. As others have already suggested, supply a reasonable clock to it, measure the sync outputs and then change the frequency accordingly. Chances are good that it's a standard and even frequency, like (for example) 16 MHz. Tilmann |
#7
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On 30/01/2013 22:26, DaveC wrote:
80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? I'd try 13.5MHz first but anything in that ballpark and output the video to a multisync monitor and you should get some sort of picture. Old monitors don't like being driven too slowly for long periods. -- Regards, Martin Brown |
#8
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. |
#9
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Martin Brown" wrote in message ... On 30/01/2013 22:26, DaveC wrote: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? I'd try 13.5MHz first but anything in that ballpark and output the video to a multisync monitor and you should get some sort of picture. Old monitors don't like being driven too slowly for long periods. They don't have to be old - just have a CRT. The scan yoke being an inductor has linear ramp current when the voltage is applied for the forward scan period, reducing the frequency increases the period - the inductor has time to saturate and "punch-through" the scan transistor! |
#10
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Ian Field wrote: "Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. Did you just figure that out? |
#11
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On 7.2.13 11:35 , Ian Field wrote:
"Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. Not quite. In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz, the ratio is 283.75512, not an exact multiple. When I studied the thing in the 60's, the explanation was to find a frequency at as non-integer rate as possible, to get rid of Moire effects. -- Tauno Voipio |
#12
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On 7.2.13 11:42 , Ian Field wrote:
"Martin Brown" wrote in message ... On 30/01/2013 22:26, DaveC wrote: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? I'd try 13.5MHz first but anything in that ballpark and output the video to a multisync monitor and you should get some sort of picture. Old monitors don't like being driven too slowly for long periods. They don't have to be old - just have a CRT. The scan yoke being an inductor has linear ramp current when the voltage is applied for the forward scan period, reducing the frequency increases the period - the inductor has time to saturate and "punch-through" the scan transistor! There is another consideration: The scan system is resonated on the third harmonic to the line rate to create the S-correction for the scan, slower on the edges and faster at the middle. This is to compensate for the varying distance between the electron gun and the screen. This means to keep the line rate within a few percent of the nominal. The method was populas with the monochrome tubes, but colour things often use more sophistacated methods (parabolic correction, etc). -- Tauno Voipio |
#13
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Thu, 7 Feb 2013 21:35:38 -0000, "Ian Field"
wrote: "Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. You mean fractional multiplier ? The B&W contains spectral peaks at multiplies of line and field rate. For (stationary) images, there is no energy between the spectral lines. The whole idea of both NTSC and PAL (but not SECAM) is to code the chrominance signal into these "empty" spaces and thus the subcarrier must be at some submultiple of the line rate. In PAL there is an additional 25 Hz frequency shift, thus the same phase relationship occurs every 4th field. While this spectrum interleaving works pretty well for stationary images, any movement will spread the spectral lines and luminance and chrominance can no longer be perfectly separated, causing cross chrominance and cross luminance problems. For this reason ties with small details should not be used in TV studios if it is expected that the signal could be transported through NTSC/PAL, since a tie with only small B/W stripes would cause a quite colourful result :-). |
#14
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
In PAL & NTSC the colour carrier was a multiple of the line rate.
Not quite. In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz, the ratio is 283.75512, not an exact multiple. When I studied the thing in the 60's, the explanation was to find a frequency at as non-integer rate as possible, to get rid of moire effects. This is not a correct explanation -- and I'm certain your numbers are wrong (you've rounded off the line rate). The subcarrier HAS to be a multiple of the line rate -- specifically, an odd multiple of half the line rate -- or the sidebands of the color signal will not properly interleave with the sidebands of the luminance signal. By the way, moire is not capitalized. It is not a person's name. |
#15
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
The B&W contains spectral peaks at multiplies of line and field rate.
For (stationary) images, there is no energy between the spectral lines. This is not correct, unless every line is like every other line. The normal variation in vertical details causes the peaks to "smear" somewhat. |
#16
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On a sunny day (Fri, 8 Feb 2013 06:47:57 -0800) it happened "William
Sommerwerck" wrote in : In PAL & NTSC the colour carrier was a multiple of the line rate. Not quite. In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz, the ratio is 283.75512, not an exact multiple. When I studied the thing in the 60's, the explanation was to find a frequency at as non-integer rate as possible, to get rid of moire effects. This is not a correct explanation -- and I'm certain your numbers are wrong (you've rounded off the line rate). The subcarrier HAS to be a multiple of the line rate -- specifically, an odd multiple of half the line rate -- or the sidebands of the color signal will not properly interleave with the sidebands of the luminance signal. By the way, moire is not capitalized. It is not a person's name. In PAL 25 Hz is added to the color subcarrier to force the interference pattern caused by chroma in the BW picture to move, so it becomes less visible. From: http://en.wikipedia.org/wiki/PAL: quote The 4.43361875 MHz frequency of the colour carrier is a result of 283.75 colour clock cycles per line plus a 25 Hz offset to avoid interferences. Since the line frequency (number of lines per second) is 15625 Hz (625 lines × 50 Hz ÷ 2), the colour carrier frequency calculates as follows: 4.43361875 MHz = 283.75 × 15625 Hz + 25 Hz. end quote |
#17
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"William Sommerwerck" wrote in message ... By the way, moire is not capitalized. It is not a person's name. Maybe not the way he used it, but it is a girl's first name. http://www.thinkbabynames.com/meaning/0/Moire |
#18
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Fri, 8 Feb 2013 10:39:39 -0500, "Rich."
wrote: "William Sommerwerck" wrote in message ... By the way, moire is not capitalized. It is not a person's name. Maybe not the way he used it, but it is a girl's first name. http://www.thinkbabynames.com/meaning/0/Moire When two patterns of lines cross to form new designs, that's a moiré. |
#19
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On 2/8/2013 7:48 AM, Tauno Voipio wrote:
On 7.2.13 11:35 , Ian Field wrote: "Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. Not quite. In PAL, the subcarrier is 4.433618 MHz and the line rate is 15625 Hz, the ratio is 283.75512, not an exact multiple. As far as I know it is 283.75 fH + 1/2 fV = 283.75 fH + 25 Hz = 4433618.75 Hz I don't recall why. But Google has the answer: http://www.db0anf.de/app/bbs/messages/show-460135PA2RHB To make the dot pattern that results from the colour subcarrier almost invisible, we need to satisfy this equation: 4*fc - 2*fr fl = line frequency (15625 Hz) fl = ----------- fc = colour subcarrier frequency n fr = frame rate (50 Hz) This will ensure that dark and light dots cancel each other as much as possible between alternating lines and between alternating frames. The number n must be odd, and high enough to get a high enough colour frequency. It was chosen to be 1135. We get 4*fc - 2*fr = 1135 * 15625 fc = 1135 * 15625/4 + 25 = 4433593.75 + 25 = 4433618.75 Hz Note: when colour television was first on the air, we did not have the 25 Hz offset yet. And although the dot pattern should have cancelled over the screen, it was visible and you could tell, from watching your old black and white screen, that a colour transmission was on. After adding in the 25 Hz "time compensating" offset, this was no more. The "integration time" for the screen is 4 frames, or 80 milliseconds. If you could photograph the screen with that as the exposure time, the dot pattern would be absolutely invisible. If you took a picture with an exposure time of 2 frames (40 ms), or in other words exactly one complete screen, you could see the residual dot pattern. |
#20
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Fri, 8 Feb 2013 06:49:10 -0800, "William Sommerwerck"
wrote: The B&W contains spectral peaks at multiplies of line and field rate. For (stationary) images, there is no energy between the spectral lines. This is not correct, unless every line is like every other line. The normal variation in vertical details causes the peaks to "smear" somewhat. I have quite often used the following example what the B&W signal looks like: There are quite often repeating hills every 15625 Hz with a tree standing at every 25 Hz starting from the top of the hill With severe wind (image movement) the tree branches will be mixed with each other, making it impossible to separate luminance and chrominance properly. |
#21
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
wrote in message ...
On Fri, 8 Feb 2013 06:49:10 -0800, "William Sommerwerck" wrote: The B&W contains spectral peaks at multiplies of line and field rate. For (stationary) images, there is no energy between the spectral lines. This is not correct, unless every line is like every other line. The normal variation in vertical details causes the peaks to "smear" somewhat. I have quite often used the following example what the B&W signal looks like: There are quite often repeating hills every 15625 Hz with a tree standing at every 25 Hz starting from the top of the hill With severe wind (image movement) the tree branches will be mixed with each other, making it impossible to separate luminance and chrominance properly. True, but you're missing the point of what I said. "Movement" is sufficient, but not necessary. Changes in vertical detail produce same effect. That is, no ordinary object is the same from line to line. |
#22
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Jan 30, 4:26*pm, DaveC wrote:
80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) There is no video signal on the BNC output connector. This is used equipment being resurrected, so operational history is unknown. There is a place on the video card labeled "Q2" that is the right shape & size for a crystal can. The pads look like it was ripped off the board: a short lead soldered in one pad; a hole in the other pad where a lead was soldered (poorly, apparently!). (Rough handling is a distinct possibility: the client is a used-equipment dealer and the fork lift is their main tool...). The board is populated with 80's technology, mainly 74LS' :: the crystal pads connect to an 'LS04 inverter/driver and then to an 'LS96 parallel-to-serial converter. The 'LS96 spec sheet says that it can be driver up to 25 MHz. The board uses a 8275 CRT controller, and in the datasheet it says: "CCLK is a multiple of the dot clock and an input to the 8275." Maybe these clues will tell someone what frequency this crystal needs to be...? What frequency crystal should I be looking for? Thanks. Do you have pictures ? |
#23
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Michael A. Terrell" wrote in message m... Ian Field wrote: "Tilmann Reh" wrote in message ... Michael A. Terrell schrieb: 80's vintage German printing equipment (offset press industry) uses a video plug-in card (made by the manufacturer of this equipment) to generate parameter display for the operator. The display is a standard baseband video tube monitor. (It is possible, being German and sold in the USA market, that the video may be NTSC or PAL.) If it's monochrome, we don't need to talk about NTSC or PAL and their particular color carrier frequencies... In PAL & NTSC; the colour carrier was a multiple of the line rate. Did you just figure that out? That's a pretty feeble attempt - even for you! |
#24
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Michael A. Terrell" wrote: Ian Field wrote: ? ? "Tilmann Reh" ? wrote in message ? ... ? ? Michael A. Terrell schrieb: ? ? ? ??? 80's vintage German printing equipment (offset press industry) uses a ? ??? video ? ??? plug-in card (made by the manufacturer of this equipment) to generate ? ??? parameter display for the operator. The display is a standard baseband ? ??? video ? ??? tube monitor. (It is possible, being German and sold in the USA market, ? ??? that ? ??? the video may be NTSC or PAL.) ? ? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ? ? particular color carrier frequencies... ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. WHICH NTSC? There are two. My first approach would be to see if anyone else still used the same equipment and ask if they have the manuals, or would let you take some photos for reference. Failing that: https://docs.google.com/file/d/0B9rh9tVI0J5mOGFjYmM1ZTctMDNhOS00OTY5LTk4MTMtZDBlZ jZhNzFmMzVh/edit uses a 22.68 MHz crystal, then a divide by two for 11.34 MHz. It also has the code for the system. The problem is that there are too many registers in that IC to give a pat answer. You would have to disassemble the EPROMs to see how it was configured and calculate the clock for yourself. I would use a scope or frequency counter to see what the free running H scan is on the monitor. (15,750 was NTSC Mono, and used on mono computer monitors in the US.) Then I would disconnect the monitor and try a crystal you think might be close enough to work, then measure the horizontal drive frequency. A little math will get you in the ballpark. The "CRT Controller Handbook" covered this CRTC, but I can't locate my copy right now. There are several on Ebay for under $2 & shipping right now. I believe that it covered the 8275 timing calculations, but I haven't used the book in 20 years. http://www.ebay.com/ctg/CRT-Controller-Handbook-Gerry-Kane-1985-Paperback-/4929442 |
#25
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Michael A. Terrell" wrote in message ... "Michael A. Terrell" wrote: Ian Field wrote: ? ? "Tilmann Reh" ? wrote in message ? ... ? ? Michael A. Terrell schrieb: ? ? ? ??? 80's vintage German printing equipment (offset press industry) uses a ? ??? video ? ??? plug-in card (made by the manufacturer of this equipment) to generate ? ??? parameter display for the operator. The display is a standard baseband ? ??? video ? ??? tube monitor. (It is possible, being German and sold in the USA market, ? ??? that ? ??? the video may be NTSC or PAL.) ? ? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ? ? particular color carrier frequencies... ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. WHICH NTSC? There are two. Twice never twice the same colour?! |
#26
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Ian Field wrote: "Michael A. Terrell" ? wrote in message ... ? ? "Michael A. Terrell" wrote: ?? ?? Ian Field wrote: ?? ? ?? ? "Tilmann Reh" ? wrote in message ?? ? ... ?? ? ? Michael A. Terrell schrieb: ?? ? ? ?? ? ??? 80's vintage German printing equipment (offset press industry) uses ?? a ?? ? ??? video ?? ? ??? plug-in card (made by the manufacturer of this equipment) to ?? generate ?? ? ??? parameter display for the operator. The display is a standard ?? baseband ?? ? ??? video ?? ? ??? tube monitor. (It is possible, being German and sold in the USA ?? market, ?? ? ??? that ?? ? ??? the video may be NTSC or PAL.) ?? ? ? ?? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ?? ? ? particular color carrier frequencies... ?? ? ? ?? ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. ? ? ? WHICH NTSC? There are two. Twice never twice the same colour?! Keep showing your vast ignorance. The first "National Television Standards Committee" was for Monochrome. The second "National Television Standards Committee" was for color, so 'NTSC' doesn't have 'color' anywhere in the title. They changed the Horizontal rate from 15,750 Hz to 15,734.264 Hz to eliminate a beat in the chroma. That 16 Hz difference allowed older TVs to receive the color broadcasts. The original NTSC was still used for mono security cameras. As always, you add nothing useful to any thread you butt into. rather, you show what an ignorant ass you are. Maybe we should call you 'Mule', or 'Donkey Boy' to honor your lame assed attempts? Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. |
#27
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Sun, 10 Feb 2013 15:10:14 -0500, the renowned "Michael A. Terrell"
wrote: Keep showing your vast ignorance. The first "National Television Standards Committee" was for Monochrome. The second "National Television Standards Committee" was for color, so 'NTSC' doesn't have 'color' anywhere in the title Hmm... "National Television Standards Committee" NTSC 68,200 results NTSC "Never Twice the same Colour" OR "Never Twice the same Color" 248,000 results But I think the real answer is "National Television System Committee" NTSC 1,480,000 results Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#28
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Michael A. Terrell" wrote in message m... Ian Field wrote: "Michael A. Terrell" ? wrote in message ... ? ? "Michael A. Terrell" wrote: ?? ?? Ian Field wrote: ?? ? ?? ? "Tilmann Reh" ? wrote in message ?? ? ... ?? ? ? Michael A. Terrell schrieb: ?? ? ? ?? ? ??? 80's vintage German printing equipment (offset press industry) uses ?? a ?? ? ??? video ?? ? ??? plug-in card (made by the manufacturer of this equipment) to ?? generate ?? ? ??? parameter display for the operator. The display is a standard ?? baseband ?? ? ??? video ?? ? ??? tube monitor. (It is possible, being German and sold in the USA ?? market, ?? ? ??? that ?? ? ??? the video may be NTSC or PAL.) ?? ? ? ?? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ?? ? ? particular color carrier frequencies... ?? ? ? ?? ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. ? ? ? WHICH NTSC? There are two. Twice never twice the same colour?! Keep showing your vast ignorance. The first "National Television Standards Committee" was for Monochrome. The second "National Television Standards Committee" was for color, so 'NTSC' doesn't have 'color' anywhere in the title. They changed the Horizontal rate from 15,750 Hz to 15,734.264 Hz to eliminate a beat in the chroma. That 16 Hz difference allowed older TVs to receive the color broadcasts. The original NTSC was still used for mono security cameras. As always, you add nothing useful to any thread you butt into. rather, you show what an ignorant ass you are. Maybe we should call you 'Mule', or 'Donkey Boy' to honor your lame assed attempts? Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. What a pity you're a senile old fart with nothing to contribute except what's been obsolete for decades. |
#29
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Ian Field wrote: What a pity you're a senile old fart with nothing to contribute except what's been obsolete for decades. What a pity that you were born, and have never done anything but take. |
#30
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Michael A. Terrell" wrote in message m... Ian Field wrote: What a pity you're a senile old fart with nothing to contribute except what's been obsolete for decades. What a pity that you were born, and have never done anything but take. Take what exactly? I take enough of your senile ranting! |
#31
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Spehro Pefhany wrote: On Sun, 10 Feb 2013 15:10:14 -0500, the renowned "Michael A. Terrell" ? wrote: ? ? Keep showing your vast ignorance. The first "National Television ?Standards Committee" was for Monochrome. The second "National ?Television Standards Committee" was for color, so 'NTSC' doesn't have ?'color' anywhere in the title Hmm... "National Television Standards Committee" NTSC 68,200 results NTSC "Never Twice the same Colour" OR "Never Twice the same Color" 248,000 results But I think the real answer is "National Television System Committee" NTSC 1,480,000 results That's what I get for not looking it up. The last time I did was in the mid '70s, when I stumbled across a book of the committee's proceedings in the old Crosley engineering library. |
#32
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On 10/02/2013 17:39, Ian Field wrote:
"Michael A. Terrell" wrote in message ... "Michael A. Terrell" wrote: Ian Field wrote: ? ? "Tilmann Reh" ? wrote in message ? ... ? ? Michael A. Terrell schrieb: ? ? ? ??? 80's vintage German printing equipment (offset press industry) uses a ? ??? video ? ??? plug-in card (made by the manufacturer of this equipment) to generate ? ??? parameter display for the operator. The display is a standard baseband ? ??? video ? ??? tube monitor. (It is possible, being German and sold in the USA market, ? ??? that ? ??? the video may be NTSC or PAL.) ? ? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ? ? particular color carrier frequencies... ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. WHICH NTSC? There are two. Twice never twice the same colour?! I always thought that too from watching US terrestrial TV until I saw the Japanese implementation of NTSC colour which works correctly. No need to clamp the newscasters face to an eerie shade of pale orange to avoid him drifting between a zombie green and purple flesh tone. ISTR NTSC-J differs really only in the black level and blanking which means that a tweak of the brightness control makes it work in the USA. They were making full multistandard kit for the expat market back in the early 1990's also with a tweak for bilingual TV mode allowing the R-L sound channel to be presented as a mono channel on demand. The main difference seemed to be like with RIAA equalisation that the Japanese engineers read the specification and implemented it fully where as the US engineered version was "near enough" and cheaper. PAL was more complex still but got around the inherent drift problems by having phase alternate line so on average chroma drifts cancel out. -- Regards, Martin Brown |
#33
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Martin Brown wrote:
The main difference seemed to be like with RIAA equalisation that the Japanese engineers read the specification and implemented it fully where as the US engineered version was "near enough" and cheaper. PAL was more complex still but got around the inherent drift problems by having phase alternate line so on average chroma drifts cancel out. According to many postings here, NTSC originated the alternating line phase shift. It was not necessary in the US due to the difference in the way that TV signals were disseminated off the air, e.g. between the studio and the transmitter. The problem with the odd color shifts, or lack of color stability in the US was usually a problem between the camera and the transmitter due to something not being properly adjusted. Bear in mind that the US had NTSC on the street in the 1953, the BBC did not broadcast in color at all until the end of 1967, and regularly two years later. So if there was any reason to adopt the phase alternating line color sync (which there was in retrospect), the BBC had 14 years to figure it out. Geoff. -- Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379 Gung Hay Fat Choy! (May the new year be prosperous). |
#34
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
In message , Geoffrey S.
Mendelson writes Martin Brown wrote: The main difference seemed to be like with RIAA equalisation that the Japanese engineers read the specification and implemented it fully where as the US engineered version was "near enough" and cheaper. PAL was more complex still but got around the inherent drift problems by having phase alternate line so on average chroma drifts cancel out. According to many postings here, NTSC originated the alternating line phase shift. It was not necessary in the US due to the difference in the way that TV signals were disseminated off the air, e.g. between the studio and the transmitter. The problem with the odd color shifts, or lack of color stability in the US was usually a problem between the camera and the transmitter due to something not being properly adjusted. Bear in mind that the US had NTSC on the street in the 1953, the BBC did not broadcast in color at all until the end of 1967, and regularly two years later. So if there was any reason to adopt the phase alternating line color sync (which there was in retrospect), the BBC had 14 years to figure it out. Wikipedia seems to give a pretty comprehensive account of the history of NTSC etc. http://en.wikipedia.org/wiki/NTSC The later development of a colour system which compatible with the existing monochrome transmissions was indeed ingenious. The BBC officially launched their regular scheduled colour TV service in 1967. http://news.bbc.co.uk/onthisday/hi/d...ewsid_2514000/ 2514719.stm However, they had been broadcasting various engineering and trade test programmes (using the normal 625-line PAL) for some years. Prior to that, they had been trying various colour systems and line standards (including, I believe NTSC on 405-lines). However, despite the politically shilly-shallying, it was pretty obvious that they were going to end up with PAL. -- Ian |
#35
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Geoffrey S. Mendelson" wrote: Martin Brown wrote: The main difference seemed to be like with RIAA equalisation that the Japanese engineers read the specification and implemented it fully where as the US engineered version was "near enough" and cheaper. PAL was more complex still but got around the inherent drift problems by having phase alternate line so on average chroma drifts cancel out. According to many postings here, NTSC originated the alternating line phase shift. It was not necessary in the US due to the difference in the way that TV signals were disseminated off the air, e.g. between the studio and the transmitter. The problem with the odd color shifts, or lack of color stability in the US was usually a problem between the camera and the transmitter due to something not being properly adjusted. Bear in mind that the US had NTSC on the street in the 1953, the BBC did not broadcast in color at all until the end of 1967, and regularly two years later. So if there was any reason to adopt the phase alternating line color sync (which there was in retrospect), the BBC had 14 years to figure it out. The phase shift in the chroma was mot obvious on coast to coast network feeds, when it was carried on a mix of coaxial and microwave networks. The addition of VITS eliminated the need to adjust the equalization at every hop. This has been discussed repeatedly, but the British trolls just can't grasp the concept. The earliest US TV network feeds didn't cross the country. 16 mm film was sent to various regions, and live national news didn't have the bandwidth for a flat response so detail was lost. Even worse was Kinescope film for Monochrome time shifting, or for places with no network feed. Hell, the TV stations in Alaska were still getting their network feed on 2" video tape into the mid '70s because Sat TV wasn't available, and the White Alice network just didn't have the spare bandwidth for video. It barely handled the AFN radio network and military TTY. Of course, it was built in the '40s for military communications, then opened to civilian traffic at a later date. Color in house, and over the STL to the transmitter was no problem, once all vacuum tube equipment was phased out. The station's sync generator & vectorscopes took care of that. hell, I had a two studio feed set up for a telethon in the '80s with each studio 30 miles from the transmitter and could fade from one studio to the other with no phase shift. A pair of TBCs, but no VITS. We had the phase error well under .1% which was the limit of the TBCs calibration. |
#36
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
"Martin Brown" wrote in message ... On 10/02/2013 17:39, Ian Field wrote: "Michael A. Terrell" wrote in message ... "Michael A. Terrell" wrote: Ian Field wrote: ? ? "Tilmann Reh" ? wrote in message ? ... ? ? Michael A. Terrell schrieb: ? ? ? ??? 80's vintage German printing equipment (offset press industry) uses a ? ??? video ? ??? plug-in card (made by the manufacturer of this equipment) to generate ? ??? parameter display for the operator. The display is a standard baseband ? ??? video ? ??? tube monitor. (It is possible, being German and sold in the USA market, ? ??? that ? ??? the video may be NTSC or PAL.) ? ? ? ? If it's monochrome, we don't need to talk about NTSC or PAL and their ? ? particular color carrier frequencies... ? In PAL ? NTSC; the colour carrier was a multiple of the line rate. WHICH NTSC? There are two. Twice never twice the same colour?! I always thought that too from watching US terrestrial TV until I saw the Japanese implementation of NTSC colour which works correctly. PAL may have given the Jap designers a bit more trouble - some of the early loss-leader sets had 2 colour subcarrier crystals - they had some pretty strange looking circuitry where the 7.8kHz ident oscillator should have been. |
#37
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
In article ,
Michael A. Terrell wrote: Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. The Intel MDS blue box system used it, if someone wants a design example. Mark Zenier Googleproofaddress(account:mzenier provider:eskimo domain:com) |
#38
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
Mark Zenier wrote: In article , Michael A. Terrell wrote: Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. The Intel MDS blue box system used it, if someone wants a design example. Was that their 8085 development system with the 8" disk drive? |
#39
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
In article ,
Michael A. Terrell wrote: Mark Zenier wrote: In article , Michael A. Terrell wrote: Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. The Intel MDS blue box system used it, if someone wants a design example. Was that their 8085 development system with the 8" disk drive? Yes. (Overdesigned slug). There were enough of them around that somebody probably has scanned the schematic and posted it on on of the document archives. Yea, there are reasons that nobody used the 8275 much. I lucky to find a 1984 databook with its datasheet on the top of my pile of boxes of databooks. Yuck. It was one of many Intel peripheral chips from the late '70s that took the wrong road. It is a programmable video counter chain (like the 6845, the one used on the IBM video cards), but instead of outputting all the address bits to feed an external memory, it had two internal 80 character display buffers that were loaded by program or DMA. (So the driver had to babysit it, making sure it got a new line of text every milisecond or so). In operation, it only output the data byte, the row counter, and some attribute bits to feed the character font ROM. (Using it for graphics, at one display line per row of data would either have saturated the micro's databus, or isn't even be possible). It only works at the level of characters, the video serializer and dot-per-character counters were external TTL. It only ran at 2 or 3 MHz. Mark Zenier Googleproofaddress(account:mzenier provider:eskimo domain:com) |
#40
Posted to alt.engineering.electrical,sci.electronics.components,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
|
|||
|
|||
Crystal frequency for monochrome video signal?
On Tue, 12 Feb 2013 23:55:12 -0500, "Michael A. Terrell"
wrote: Mark Zenier wrote: In article , Michael A. Terrell wrote: Now tell everyone how you designed dozens of commercial products with the 8275. (Which was designed for 8085 based systems.) I don't recall ever seeing one in any hardware. The 6545/6845 and the 5027 CRTC were what I've seen. The Intel MDS blue box system used it, if someone wants a design example. Was that their 8085 development system with the 8" disk drive? Diskette? |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Lost in VIDEO signal | Electronics Repair | |||
Frequency of crystal ocillator changes when counter attached, | Electronics Repair | |||
Power factor/ frequency / true rms measurement of a 230V AC 50hz signal | Electronics | |||
signal generator to frequency counter signal tap | Electronics | |||
sony video colour camera displaying monochrome only | Electronics Repair |