29 Jul
2004
29 Jul
'04
1:32 p.m.
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 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 this case, it was - I did a *LOT* of 6809 code in those days, both privately
and commercialy - I had my own debugger (still around essentually unchanged as
the MON09 debugger I list on my site), and I designed my EPROM programmer to
have the same serial port devices (6551), and RAM in the right place for the
monitor to run (ROM was at E000 of course - 8k at top in 6809 map).
Had I not had a debugged monitor, I would have written a very simple loader.
Just enough to get a "real" loader into the machine - unless I really cocked
it up, that would be all I needed, and I doubt I would have had to have the
ROM made more than once (did similar things on many other projects).
I selected the 6809 in the first place because I had recent experience with it
and suitable tools available...
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 !.
Yup - 6809 was an incredible chip - easy to multitask (and most people don't
know what DP is for!) - I always include low level debugging features/commands,
can be absolutely essential at times.
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... 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.
Not familier with UK companies etc. - this would have been somewhere in the
mid 80's, and I was reasonably well past being a student ... but these are
the kinds of things I would have tried had I still been in school:
- Local companies that were "friendly" ... might involve having a friend
who's dad worked there.
- Local shops, schools etc.
- BBS systems - lots of other "geeks" hung out there, many with good
connections... fidonet was king before the internet.
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?