8 Jun
2014
8 Jun
'14
9:59 a.m.
On 06/08/2014 12:01 AM, Eric Smith wrote:
1) I can't identify any obvious data separator
circuitry, so they're
probably using something really crude and unreliable rather than a PLL.
Take a look at some of the WD179x app notes, particularly the variations
on data separators. There are several decent ones using counters
(digital rather than analog) that are actually quite good. I'll wager
that you'll probably find your circuit there.
2) Why would they use a 6402 for the console serial
port rather than a Z80
SIO?
The SIO was expensive in comparison to the other commodity UARTs. In
particular, there was a significant cost advantage to using the DART
instead of the SIO if one didn't need sync.
The Signetics 2651 was also a popular USART back then, the big advantage
being that it had its own baud rate generator on-chip and was only a
28-pin DIP.
The 8" Quay is interesting--the only Quay sample I have is the 5.25"
(5,1024) version.
What's the part number for the PWA on the 8" drive that you have?
--Chuck