Ian Field wrote:

"Michael A. Terrell" wrote in message
m...

Ian Field wrote:

"Michael A. Terrell" wrote in message
...

Joel Koltner wrote:

"BobW" ? wrote in message
...
? We sure had fun - as did Jobs and Wozniak (from what I read).

One of Wozniak's claims to fame was that his blue box generated all
the
tones
digitally.

He became quite good at abusing digital chips for analog purposes --
he
did
similarly creative/ugly things when generating (NTSC) color on the
Apple
II,
adding almost no cost to the design in the process. Such a feat was
largely
unmatched for years; it was really only complete graphics ICs like the
Commodore VIC and perhaps the Motorola 6845/6847 that -- eventually,
as
volumes increased and prices dropped -- outperformed Woz's approach on
a
price/performance basis.


Did you ever look at that Apple II video on a waveform monitor? The
ones I saw were nasty. The C64 was cleaner than some low end ($1000)
NTSC Color character generators.

AFAICR the PAL standard Commodores used a 4x 4.433MHz crystal with a
quadrature divider to avoid a lot of complicated analogue stuff.

I never saw a PAL version, but the NTSC was 4*3.57954545 MHz

That would probably be a simple divide by 4, the PAL system effectively
requires 2 subcarrier bursts in quadrature, using a 4x crystal and a
quadrature divider neatly avoids the conventional (semi) analogue approach
of shifting the subcarrier oscillator in a PLL.

I remember the loss-leader Jap TVs that wiped out our industry. Some makes
had 2 subcarrier crystals, one synchronised to the primary subcarrier and
the other to the quadrature phase.


And you try to tell me PAL was better! ;-)


--
You can't fix stupid. You can't even put a Band-Aid™ on it, because it's
Teflon coated.