Out of Memory?
How I upgraded the RAM on the Atari 400
By Joseph BurkeAugust 3, 2005First, some background. Back in 1979, Atari released the
400/800 line of home computers to much fanfare. It was
the first machine to use sprites in games
(player-missile graphics in Atari-speak). The 800 was
released in memory configurations ranging from 8k-48k,
the 400 with either 8k or 16k. Some other differences
between the two machines included an IBM Selectric
typewriter inspired keyboard on the 800 as opposed to
the cheaper (and harder to use) flat membrane keyboard
on the 400. The 800 also had two cartridge slots versus
one on the 400. The 400 also lacks a video out for
connecting to monitors, relying solely on an RF
modulator for output to a television. Both have four
joystick ports making them a gamers' dream, but not
every game utilized them. The Atari joystick ports are
very fast, however, and many hardware devices were
released that utilized them instead of the larger SIO
port. It was much less expensive to buy a modem that
plugged into the joystick ports than to buy an 850
interface and a modem that connected via an RS-232 port.
Back then floppy drives were expensive, so many Atari
users used a cassette player for storage so the
difference in memory size didn't make much difference
until the price of floppy drives came down and more and
more Atari users started buying them. 400 owners, soon
found out that their machines couldn't handle floppies
due to having too little RAM and were forced to either
upgrade to an 800 or send their 400 out to be upgraded,
an expensive and time consuming process.
My first Atari computer back in the middle 80's was an 800XL with 64k. After
a while, I bought a 48k 800 for running those programs that even the Translator
disk couldn't handle, so I never knew the limitations of running a machine with
less than 48k for a long time. When a 16k 400 became available to me, I grabbed
it, brought it home, and quickly found out how limiting 16k can be, especially
if you want to run a floppy drive. I wanted to upgrade the memory, but every
person I talked to and every magazine article I read declared the 400 not
upgradeable without buying an expensive upgrade and sending your machine out to
have it installed.
I was not deterred, however, and proceeded to open up my machine to see what
could be done about it. Getting the beige, plastic shell open was easy enough. I
was then faced with the monolithic aluminum shell that provides RFI insulation
for the mainboard. Once I got past my initial fear about proceeding further,
however, it was relatively easy. I still needed a memory board to replace my old
one with, though, so I took a trip to my local Atari dealer who happened to have
a 32k board for the 800 collecting dust on the shelf, so I bought it and the
experiment began in earnest.
We
need to go through a little history, here, to give you more of a feel for the
Atari scene back in those days. In the early to middle 80's, it was a common
practice for users to pull out one of the memory boards in the 800 and replace
it with a hardware device of some kind. Real time clocks, machine language
monitors, 80 column cards and others were available that fit these slots. To add
these, though, meant sacrificing some memory, so memory boards were released
with extra RAM on them so you could still install your device and have 48k. The
32k board that I bought is just such a product. Installing this in an 800 along
with a standard 16k board gives you 48k and frees up a slot for devices.
Upgrading the RAM on an 800 involves pulling out the memory boards under the
cover and replacing them with boards with a higher memory capacity, but the 400
doesn't have memory boards under the cover leaving many owners feeling that they
are stuck with whatever memory came with their machine. DOS is relatively big,
so you can't connect a floppy to a 400 until you do something about the memory.
Good news, though. The 400 can be upgraded, but it's a little bit
trickier.
First of all, the 400 only has one memory slot onboard as opposed to the 3 on
the 800. This isn't as limiting a factor as you would think, though. Now for the
tricky bit. What you have to do is disassemble your 400 to get at the memory
slot. It is housed underneath the heavy aluminum shell that I mentioned
earlier.You can do this with just a screwdriver. Once you have the aluminum
shell detached, you now have access to your lone memory slot. Simply remove the
stock memory board and replace it with one of a higher capacity. There is
another slot under there, which is also present on the 800, but that is not for
memory. It is designed for testing and troubleshooting by a technician, so
ignore it. Reassemble it all, power it on and in Basic type PRINT FRE(0) to see
your new memory size. I have been running a 400 with a 32k board designed for
the 800 for some time now, and it works great with no other modifications being
necessary.
I hope this helps someone with a 400 who wants to run DOS and has access to a
memory board with more than 16k. Maybe you can find someone in the Atari
community with the skill to upgrade your stock boards or who has an upgraded
board they are willing to part with.
