>> Parts might be a bit hard to find now - uses a 6809 CPU, 6821 PIA, a 6551
>> UART, a few 6264 SRAM's, a handful of latches and 3-4 relays to move the
>And thereing lies the problem. Presumably you need to program an EPROM
>with the firmware for this 6809. Which is somewhat hard without a
>programmer :-)...
For some perhaps - at the time, myself, and almost everyone I knew worked
for companies with programmers, so it was not a problem. You could also get
EPROM programmed at the local shop for a small fee. I also had a bytesaver
in my Altair, so I could have bootstrapped up from a 2708 if I'd had to.
I didn't program the actual firmware right away - I made a EPROM (at work)
with my 6809 monitor program in it, which allowed me to download code into
the RAM (normally all used as a data buffer), where I tested and debugged
the actual firmware - When I was happy that everything was working correctly,
I use the RAM download to program a real EPROM (almost self-booting).
If I were doing the same project today, and had absolutely no access to any
means of programming the initial EPROM, I would first post in the local groups
to see if anyone near me has a programmer, failing that, I would perhaps try
this list or other more widespread resources - I'm sure that someone somewhere
would be willing to program my monitor (or even a very simple loader would
suffice) into that first EPROM for me. All you need is the ability to get code
into the device, and you can run from there.
I guess what I am saying, is that if you are not prepared to be a little
creative, you are probably not well suited to designing/building your own
test equipment.
>I built my first EPROM programmer about 18 years ago. Programs
>2716-27128, using the 'slow' algorithm. It doesn't even handle 12.5V
>parts (I should add that feature!). 3 hand-wired boards of mostly TTL,
>with a 40 pin AY-3-1015 UART in the middle. Oh yes, it's an EPROM
>emulator as well, for the same types of EPROMs.
On my original programmer (the homebuilt one), the programming voltage
was selected by a physical switch - which selected 12.5, 21 or 25v from
"taps" on a couple of stacked regulators - not the most elegant solution,
but it worked (and continues to work).
I supported the 'fast' algotithm on all by the 2732 (which would have
required me to flip one of the relays during program/read turnaround).
Ah the "good ol days"...
Regards,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Vintage computing equipment collector.
http://www.parse.com/~ddunfield/museum/index.html
Received on Thu Jul 29 2004 - 05:06:13 BST