Needham's SA-20 EPROM Programmer
Attempting File Transfer to SA-20 Using Serial Cable
Having
been glad at just getting the SA-20 working with the serial cable, I
was *really* anxious to see if the same file I had tried to transfer to
it with the parallel cable (and failed due to missing bytes) could be
able to transfer successfully using the serial cable. So put in 2716
eprom, selected device, read chip, set file pointers, transferred to the
computer. Not bad so far, but a little slow at 9600 bps. Verified the
checksum was 34511 and matched the checksum of the eprom on the
programmer -- all looked good.
Now for the real test.
Transferring back from the PC to the SA-20. Set the SA-20 to "Receive
File" and it transferred & no on-screen File I/O error message on
the programmer like I was getting before! Checked the checksum of the
data in the memory buffer and it was 34511. AWESOME!!!
I then
played around with the baud rate a little more and set the rate to
115.2k in the software and now file transfers & navigating around on
the menus work as fast as they did with the parallel port!
Final Thoughts & Words of Wisdom
First and
foremost, if you are one of the few people actually using a programmer
this old and have problems with the parallel cable, try an RS232 null
modem serial cable. This goes for any eprom programmer really -- if it
has an RS232 connection and you see some bytes are getting screwed up
with parallel cable, it's worth a shot to try the RS232. Just be sure
it has the correct standard pinout for a null modem cable for your
programmer. I'd be interested in hearing if anyone else had similar
issues with parallel ports and older devices.
Next.. words of wisdom I guess, if you're at all like me and have a
hard time giving up on something -- it can be really *really* annoying
to invest 20+ hours into something and still not have it working. So
you have to know when it's just not worth it. But that's a fine line
cause it's hard sometimes if you like learning and figuring things
out... somehow you drag yourself back into the pain :) When you stick
with it though and are successful in the end, it's a great feeling of
accomplishment and you most likely learned a ton. I know this
eprom programmer is old and I should be buying a new one -- and I will buy a
new one soon enough since it will support many more chips, but why buy a new programmer that is spotty with
being able to program these older eproms instead of using something that
was designed to program them reliably in the first place?
Do I recommend you
buy any really old programmer and go through the same frustrating pain I
did trying to get it to work? No -- not by any means, it's a pot luck chance that an old programmer running DOS software is going to work on a newer machine. But if you buy a Willem programmer, True USB GQ-4X or a
newer USB programmer and you can't program older chips, then look for an
older programmer that supports those chips reliably & that other people
have had luck getting to work on newer computers. I do plan to buy a
newer programmer soon, most likely a GQ-4X, but this old tried &
true SA-20 will be my workhorse for the older chips that I can't program
on the newer programmers, and that's indispensible. Why throw away a
chip thinking it doesn't work when there's a chance it's actually a good eprom & it's the eprom programmer at fault?
Anyway, I hope the few other people with an SA-10 or SA-20 can save
themselves a ton of aggrivation by finding this article and also be
assured that *someone* has gotten old DOS software written in 1990 to
work under Windows XP on a 1.66ghz Core2 Duo processor using a serial cable. Now that it's fully working, I really like the SA-20! It's pretty easy to use and being
able to navigate the screens in a DOS window versus on the programmer
itself makes typing in filenames or navigating some of the menus much
faster.
Good luck and happy programming!
Comments:
No comments have yet been made.