This month I
want to cover a topic that some of us have came
across from time to time.
You get an old
Atari 8-bit computer and you find little switches
that are not part of the original system and
you wonder what they do.
On the Atari
400 some of the more common upgrades were the
replacement keyboard from membrane to regular
style keys and memory enhancement beyond the
16 KB. On the Atari 800 you had multiple
OS ROMs that could be piggy backed, memory upgrades
beyond the standard 48 KB. There have been many
add-on devices like SCSI and IDE hard drives
as well as true hardware reset switches.
The 800XL and
the 130XE had all of the above and more. You
could get a 80 column display and a 256 KB RAM
with some of the various upgrade as well as a
triple OS ROM installed via a toggle switch.
Let's look at
a typical 800XL with these enhancements. A few
months back I added another 800XL to my collection.
I noticed two additional switches and decided
to go inside to see what they were for. The
unit would power up but not give a display.
I thought there might be loose chips in
the mainboard so I had more than one reason
for wanting to go inside.
the screws I opened up my Atari 800XL and unplugged
the keyboard cable. I immediately saw the add-on cable on the right side running from the
back of the case and going under the RF shield
On the back side
of the board the cable was soldered and I discovered
this was a true hardware reset switch, unlike
the standard soft reset on the Atari 8-bit systems.
The other was
a toggle switch that went down through the RF
shield and was tied into a dual OS chip. Since
the factory chip was on top, I was not sure
as to what the second chip might be. Since there
were several chips made in this manner I could
not begin to guess which one this was.
at the mainboard I discovered additional rework
that appeared to be a "home brew"
256 KB memory upgrade from the stock 64 KB.
I looked at various
old upgrade articles I had and was not
sure which one this might be, so I sent a photo
to my friend Rick Detlefsen to get his opinion.
Rick felt it was just the standard home made
256 KB upgrade. While I was in there I reseated
several chips (this mainboard was an older one
with most of the chips in sockets instead of
being soldered to the board).
the computer and powered it up.
The system came
on just fine and the second operating system
turned out to be the Omniview 256 by David Young.
This OS allowed not only an 80 column display,
but the ability to have a 256 KB RAM disk (providing your
computer had the memory upgrade as well).
So the mystery
had been solved. This old Atari 800XL had a
256 KB memory upgrade, a dual OS upgrade and
the hardware rest switch added on by a previous
When I finished
the 800XL, I did the same thing to my older
and found a toggle switch to turn off the speaker,
a memory upgrade, a switch to disable the left
cartridge slot, dual OS and a hardware reset.
There was also the add-on Busi-Key by CT systems
connected to the keyboard connection inside.
I'll see you
next month at Atari in the USA 2002.