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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. |
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#1
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Think this through with me ...
Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg
display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? Arfa |
#2
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Think this through with me ...
My gut reaction is that you're correct -- it has no memory. I don't see
anything in it that could be used as a memory. You're right -- the "correct" way to implement a bingo counter would require a microprocessor and some memory. |
#3
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Think this through with me ...
Arfa Daily wrote in message
... Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? Arfa I repaired something similar about 15 years ago, it had upper and lower bounds set on thumbwheel sw on the top I think you could set it for auction rostrum incrementing or a random number generator but no repeat delete facility. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#4
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Think this through with me ...
Arfa Daily wrote:
Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? Arfa Well, for a proper game of Bingo, you need more than numbers, ie the letters b, i, n, g, & o. They're combined with a random number to score plays on a card, which might contain many duplicate numbers across the numeric grid, but not in the same column. So I'd say this could only be 'half' of a Bingo number generator. Something has to generate the letters. Combined with that, the numbers could indeed duplicate, just not any specified combination of number and letter. jak jak |
#5
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Think this through with me ...
On Jan 19, 7:17*am, "Arfa Daily" wrote:
So I have a good look at what's in it. *2 x 4027 dual J-K, *3 x 4011 quad NAND, * 2 x 4081 quad AND, *1 x 4040 12 stage counter, * 1 x 4020 14 stage counter, * 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. *Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or *8080 processor, maybe. First, a caveat. It's been nearly 20 years since I drifted away from digital hardware design to the dark arts of software. That said.... The 555 and the counters must be part of the logic to _generate_ the random number, based on randomly stopping the counters with the button push, the other stuff looks like it would be used for "glue" logic for the counters, and comparison for the start and stop numbers. You're right, I don't see anything that would serve as a memory to be used to check for duplicates. I think what you have is just a random number generator, and the "memory" was a paper-and-pencil operation. Jerry |
#6
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Think this through with me ...
"jakdedert" wrote in message ... Arfa Daily wrote: Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? Arfa Well, for a proper game of Bingo, you need more than numbers, ie the letters b, i, n, g, & o. They're combined with a random number to score plays on a card, which might contain many duplicate numbers across the numeric grid, but not in the same column. So I'd say this could only be 'half' of a Bingo number generator. Something has to generate the letters. Combined with that, the numbers could indeed duplicate, just not any specified combination of number and letter. jak jak 'Standard' UK bingo just requires the numbers 1 to 90. It is played on a 'set' of six tickets, each having 15 numbers arranged as 3 horizontal lines of five numbers, placed within 9 vertical columns, one each for the 10's, 20's, 30's etc http://www.coronetbingo.com/userimag...icketSmall.jpg so all 90 numbers appear. Usually played as 'treble chance' games so prizes for one line, two lines and a full house. Some games such as the high value National game is played as a full house only, but you only find this sort of game in proper commercial bingo clubs. In those establishments, the numbers are computer generated, and supposedly totally random, but they are actually far from it, with easily detectable patterns, if you watch carefully ... Arfa |
#7
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Think this through with me ...
"Jerry" wrote in message ... On Jan 19, 7:17 am, "Arfa Daily" wrote: So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. First, a caveat. It's been nearly 20 years since I drifted away from digital hardware design to the dark arts of software. That said.... The 555 and the counters must be part of the logic to _generate_ the random number, based on randomly stopping the counters with the button push, the other stuff looks like it would be used for "glue" logic for the counters, and comparison for the start and stop numbers. You're right, I don't see anything that would serve as a memory to be used to check for duplicates. I think what you have is just a random number generator, and the "memory" was a paper-and-pencil operation. Jerry Hi Jerry. Yes, that was exactly my take on what the hardware did. Just wanted a few other opinions so that I can be sure of what I'm saying, when I throw it back at the shop, who will then have to tell their customer ... :-( Arfa |
#8
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Think this through with me ...
Arfa Daily wrote:
"jakdedert" wrote in message ... Arfa Daily wrote: Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? Arfa Well, for a proper game of Bingo, you need more than numbers, ie the letters b, i, n, g, & o. They're combined with a random number to score plays on a card, which might contain many duplicate numbers across the numeric grid, but not in the same column. So I'd say this could only be 'half' of a Bingo number generator. Something has to generate the letters. Combined with that, the numbers could indeed duplicate, just not any specified combination of number and letter. jak jak 'Standard' UK bingo just requires the numbers 1 to 90. It is played on a 'set' of six tickets, each having 15 numbers arranged as 3 horizontal lines of five numbers, placed within 9 vertical columns, one each for the 10's, 20's, 30's etc http://www.coronetbingo.com/userimag...icketSmall.jpg so all 90 numbers appear. Usually played as 'treble chance' games so prizes for one line, two lines and a full house. Some games such as the high value National game is played as a full house only, but you only find this sort of game in proper commercial bingo clubs. In those establishments, the numbers are computer generated, and supposedly totally random, but they are actually far from it, with easily detectable patterns, if you watch carefully ... Arfa How interesting...an unsuspected illustration of the breadth of the gap across the pond. Here in the States, a BINGO card consists of a grid of five columns with the top row being 'bingo', the letters. Every card has a number of digits in the rows below the five letters (don't recall how many) which are combined with the letter above to produce a winning call, for example: B-29, G-50 etc. Winning any combination of numbers each of the five BINGO rows (five across, but not necessarily in a straight row) is a winning card...and the winner calls, loudly enough for the caller to hear: "Bingo!" There are probably other permutations with which I'm not familiar (There are, see: http://en.wikipedia.org/wiki/Bingo_(U.S. ); but that's the main gist of it. jak jak |
#9
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Think this through with me ...
Well, for a proper game of Bingo, you need more than numbers, ie the
letters b, i, n, g, & o. They're combined with a random number to score plays on a card, which might contain many duplicate numbers across the numeric grid, but not in the same column. So I'd say this could only be 'half' of a Bingo number generator. Something has to generate the letters. Combined with that, the numbers could indeed duplicate, just not any specified combination of number and letter. jak jak 'Standard' UK bingo just requires the numbers 1 to 90. It is played on a 'set' of six tickets, each having 15 numbers arranged as 3 horizontal lines of five numbers, placed within 9 vertical columns, one each for the 10's, 20's, 30's etc http://www.coronetbingo.com/userimag...icketSmall.jpg so all 90 numbers appear. Usually played as 'treble chance' games so prizes for one line, two lines and a full house. Some games such as the high value National game is played as a full house only, but you only find this sort of game in proper commercial bingo clubs. In those establishments, the numbers are computer generated, and supposedly totally random, but they are actually far from it, with easily detectable patterns, if you watch carefully ... Arfa How interesting...an unsuspected illustration of the breadth of the gap across the pond. Here in the States, a BINGO card consists of a grid of five columns with the top row being 'bingo', the letters. Every card has a number of digits in the rows below the five letters (don't recall how many) which are combined with the letter above to produce a winning call, for example: B-29, G-50 etc. Winning any combination of numbers each of the five BINGO rows (five across, but not necessarily in a straight row) is a winning card...and the winner calls, loudly enough for the caller to hear: "Bingo!" There are probably other permutations with which I'm not familiar (There are, see: http://en.wikipedia.org/wiki/Bingo_(U.S. ); but that's the main gist of it. jak A similar game is played here during the intervals in the main bingo. Each 'main' session is divided into sub-sessions, where up to 7 games of the six-ticket (aka "cards") bingo is played in silence, apart from the caller's voice. There is some big money at stake in these games, hence the quiet and concentration. Each number takes about 2 seconds to call with about a half to one second gap between numbers. All 'in club' games have the numbers 'single-called' as in "Two and three - twenty three". Big 'network' games (aka "link" games) played between many clubs, and the National Game (which I once won a big share of !) have the numbers double called as in " Twenty three. Two and three - twenty three". The overall call time remains the same however, as the gap between calls now shrinks to almost nothing. It's a pleasure to listen to and play with a good caller, who gets a real sing-songy rhythm going. A poor caller is actually difficult to play along with. The game is stopped by calling anything you like. "YES !!" is quite common, but "BINGO" is also sometimes used. "LINE !" or "HOUSE !" sometimes, also. One guy in the club that I used to go to regularly, used to stop the game by calling "TOP BANANA !". Another always used to bellow "HERE you are then !!" Between these main sessions, a different type of bingo known as cash bingo or party bingo or prize bingo is played. This makes use of a fully electronic touch board with fixed numbers, set in each table top. The numbers are again in columns, but this time, each column has a colour, the equivalent I guess of each of your columns each having a letter assigned to them. There are 16 numbers in total and most games are played to win by four across, four down, four on either diagonal, or four corners. Some in-house games are played as a full house where you need to light all sixteen numbers, and all network or linked-up games between clubs are full house. It's called very quickly with no gaps at all between the calls. Caller tends to sound a bit like an auctioneer. I can't for the life of me remember the colour allocations, but it is called like "Red five yellow forty red fourteen blue thirty six" and so on like a machine gun firing. Total time for a four winning number game is typically 20 seconds. Games are paid for by inserting coins at the table. With it being fully electronic, all wins are just automatically flagged at the caller's station, but you still have to stop the game by waving your hand over the 'win' lozenge on the board. Some callers will pause a short time when they see on their board that there is a winner, but most just carry right on, and if you miss it, that's just your fault. Prizes are paid in cash and brought to your table by a runner. The electronic touch boards are quite new. It used to be done with a board with mechanical shutters over the numbers. The board that you were playing was identified to the system by the coin mech that you had put your money in. You used to have to be careful that the board number matched the coin mech number, and that no one had moved the boards between tables ... ! The tabletop bingo is played with a lot of noise in the club, being between sub sessions. People are up and on the move getting food, drinks, playing slots etc (oh, and going outside to the smoking area, since it has been banned inside any public place in the UK now ). All of which has absolutely nothing to do with electronics, but as you say, it is interesting to highlight the differences between our cultures, which many people perceive as being broadly the same. I've never really managed to get my head around Keno when I've been in Vegas, but that's another story ... :-) Arfa |
#10
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Think this through with me ...
The lack of subjective randomness is not necessarily a problem, as the
players cannot choose their own cards. And the repetition of numbers probably doesn't matter, as long as they all eventually come up. |
#11
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Think this through with me ...
"William Sommerwerck" wrote in message ... The lack of subjective randomness is not necessarily a problem, as the players cannot choose their own cards. And the repetition of numbers probably doesn't matter, as long as they all eventually come up. First point agreed. See my reply to Baron. As to the other point, it does matter as, if there is no comparison to check if a number has been generated already and thus needs another to be generated if it has, there could be no average game length, which is very important in a commercial club where they have to be ready at very specific times to jump online for linked games. Games are surprisingly consistent at 5 minutes apiece, including the win checks. Arfa |
#12
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Think this through with me ...
Arfa Daily wrote: Booked in by shop as a 'Bingo calling unit'. It has a large 5 digit 7 seg display made from discrete LEDs. Has two 5 digit BCD encoded switch units to set start and end number. Has jack input to which is connected a hand-held push button unit. Chip date codes indicate that this thing is from 1981. It looks 'professionally' hand built, if you see what I mean. It has stickers on with a company name, but that could be largely meaningless. Two problems reported. First that it had a problem with the LEDs, and secondly that it had "lost its memory". LED problem was straightforward enough. One segment of one digit was not lighting due to one LED in the series chain of five which made up the segment, being open circuit. A replacement LED restored that. Now, the second problem. For playing bingo, the start number would be set to "1", and the end number to "90". All ok so far, and if this is done, it does indeed generate random numbers in the range 1 to 90, one per button push. The next requirement is that the unit is going to need to know for any game in progress, which of the numbers between 1 and 90 that it has already produced so that they are not duplicated, and this is where it all goes tits up. After a while, numbers *do* start to duplicate. If you set the start and end numbers to say "1" and "10", it might take 15 button pushes to get all ten numbers out, the other five being one or more times dups. So I have a good look at what's in it. 2 x 4027 dual J-K, 3 x 4011 quad NAND, 2 x 4081 quad AND, 1 x 4040 12 stage counter, 1 x 4020 14 stage counter, 1 x 555 timer and last but not least, 1 x MK50395 decoder / driver. Now I don't know if I'm just being dumb-arsed here, or having a senior moment, but I'm buggered if I can see any chips in that line up that could form a memory and comparator for potentially 99999 numbers. Or even for 90 numbers come to that ... If this is what it was meant to do, even back in '81, I would have expected to see a couple of CMOS memory chips, and a Z80 or 8080 processor, maybe. What am I missing here ? Could it be that they are mistaken in thinking that it can be used to properly call a game of bingo ? Is it in fact a raffle ticket drawing machine, where you would set the serial numbers of the first and last tickets sold out of a batch of perhaps 1000 and then draw maybe 10 prize ticket numbers with the chances of it duplicating any when it's only generating ten random numbers out of a pool of 1000, being at worst, slim ? Haven't managed to get hold of the owners again yet to check if they feel that it has ever worked as a bingo calling machine, but at the moment, my feeling is that it is a 'new acquisition' to some little club, and that it has been given to them after sitting long forgotten in an attic somewhere for 20 years. Any thoughts anyone ? I think you're spot on. Graham |
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