29 Jul
2004
29 Jul
'04
9:32 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? 
30 Jul
30 Jul
12:07 a.m.
My "not available" story: I was at my
parents home over a long weekend when I
finally got my wirewrapped 8080 system to the point where it could use a keyboard
- as they lived in the country, there was no chance of scrounging one (I couldn't
afford to BUY anything back then), so I decided to build one...
Off-thread, but majorly on-topic for the list...
A could of years before I built the programmer (this would be 1986 IIRC),
I was designing my own computer (which I've still not finished, you know
how these projects go on :-)). Anyway, I needed a keyboard, and I saw an
advert for cheap encoded QWERTY keyboards in the back of a magazine.
Since it was nearby I decided to investigate...
I did buy a keyboard, I still have it. I also bought a Philips P850
minicomputer, my first TTL-built processor. That's the machine that got
me into computer collecting/repair...
Just think... Had I been able to buy a PC-clone keyboard for a few pounds
in just about any computer shop, I may well have never found this hobby...
I selected the 6809 in the first place because I had
recent experience with it
and suitable tools available...
I used the 6809 becuase I could cross-develop code on my CoCo (running
OS-9) which was by far the best development environment I had access to
at the time...
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.
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.
May have worked, altough I can't think of anyone who would have been able
to get me access to a programmer (and then there was the issue of
actually getting the data onto their machine, not many people could read
OS-9 disks...)
- Local shops, schools etc.
Would not have worked. UK schools at that time did not have EPROM
programmers (I doubt they do now). Never saw a shop with one either.
Maybe I could have found somebody who made pirate BBC micro ROMs (this
seemed to be the common use for EPROM programemrs among the general
public at that itme...) and asked them to burn me a chip, but...
It was easier just to make a programmer.
but.. especially in todays world (as you point out),
having to get the "first"
ROM programmed should not be a show stopper. Even that is only an issue if the
These days it's a lot easier.... I am sure many people here have, or have
access to, an EPROM programmer, and would program the odd chip if sent an
image. And it's a lot easier to transfer said image now than it was 20
years ago...
-tony
4:16 a.m.
In message <20040730013222.JQCO2991.orval.sprint.ca(a)smtp.sprint.ca>
Dave Dunfield <dave04a(a)dunfield.com> wrote:
but.. especially in todays world (as you point out),
having to get the "first"
ROM programmed should not be a show stopper. Even that is only an issue if the
OP decided to build my design "as is" - as discussed earlier in this message,
a little flash device could be used and then all you need is a serial or parallel
port to program it (depending on the requirements of the device). To me (primarily
a software guy), using a little controller with lots of I/O and ability to time
pulses far more accurately than winblows, it still makes sense to design a micro
based device.
The other option if you need to make a bootstrap ROM and don't have access to
a programmer would be the "DIP switch and monostable" trick. A one-shot
monostable generates the program pulse, a bunch of DIP switches set the
address and data locations. A momentary pushbutton switch fires the
monostable, which gives the EPROM a 50mS program pulse, then waits for the
key to be released.
If I did something like that today, I'd probably use a few TIL311s, a 4040
counter and a bunch of switches. Or I'd use a PIC microcontroller and a
bit of assembler code to program the ROM.
Later.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem(a)dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI
... My haystack had no needle!
31 Jul
31 Jul
5:05 p.m.
Philip Pemberton wrote:
If I did something like that today, I'd probably
use a few TIL311s, a 4040
counter and a bunch of switches. Or I'd use a PIC microcontroller and a
bit of assembler code to program the ROM.
And how would you get the program into the PIC? :-)
--
John Honniball
coredump(a)gifford.co.uk
7234
days inactive
7236
days old
3 comments
4 participants
participants (4)
-
ard＠p850ug1.demon.co.uk -
coredump＠gifford.co.uk -
dave04a＠dunfield.com -
philpem＠dsl.pipex.com