28 Jul
2004
28 Jul
'04
10:06 p.m.
> 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
29 Jul
29 Jul
11:35 a.m.
> 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
There were mail-order companies who would do this in the UK, but they
charged qyite a bit for doing it (especially if they had to type in a
listing). At the time I didn't have a machine that wrote any form of
'standard' floppy disks (i.e. I didn't have an IBM PC).
Unless your programming skills are perfect (and mine are not), this gets
boring fast when you have to wait a few days for each update. In fact the
time taken to erase and reporgram an EPROM yourself soon becomes painful,
that's why I included an emulator in my programmer.
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
Right... Again this assumes your monitor is debugged.
Incidentally, I've built a couple of instruments with microprocessors (as
opossed to microcontrollers) controlling them (actually I normally used
the 6809 -- nice chip), and I included commands to read/write/execute
from any location in mmeory. Sure helped debugging !.
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).
Neat.
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
These days I'd either use a PIC as the controller processor (trivial to
make a programmer for, and the programming algorithms are documented), or
if I was using some deviec with external program memory, I'd start off
using E2PROM or something, again easy to make a programmer for. I now
have access to rather more computers, with rather more user I/O lines...
to see if anyone near me has a programmer, failing
that, I would perhaps try
This was long before the days of the Internet in the UK. It wasn't easy to
find places to ask about borrowing a programmer.
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
These days it's easy. I have a dozen programmers, and could build another
one in an afternoon without even thinking about it. And there are people
on this list who'd burn an EPROM from an Intel-hex file e-mailed to them.
This was not the case 18 years ago.
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.
Are you saying I'm not creative? Heck, I got round the problems and built
a working programmer. I guess I should tell you how I verified the
program pulse width without an accurate counter. I used a TTL monostable
to generate the 50ms pulse, you see. I connected the input to a known
clock frequency (about 5Hz IIRC), divided down from an Xtal. The output
went to a buffer which I'd measured the output voltages (high and low)
for under static conditions. When the whole lot was patched together, I
measured the average output voltage using an analogue meter. From that I
could calculate the mark/space ratio. And thus the pulse width (knowing
the repition frequency). Worked well enough to program quite a few EPROMs...
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
7451
days inactive
7451
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ard＠p850ug1.demon.co.uk -
dave04a＠dunfield.com