m o r e
ROM means "Read-Only Memory". It is placed in a chip on a silicon circuit board,
and a lot of technical products use them. There is one in your computer, in your car, in
your CD-player, maybe even one in your food-processor. There is also one (or more) in your
2600 cart. It's where the actual game is put on. Collectors, gamers and programmers often call
the entire inside of the carts the ROM, or they refer to the game the ROM.
EPROM means "Erasable and Programmable Read-Only Memory".
Basically, it is the same as a ROM, but you can Write on it, over and over, after you have
Erased it. EPROMs have a small lense or window on the chip By shining intense Ultra-Violet Light
through it (for about an hour) you can erase the EPROM. For "burning"
the data onto the EPROM, it has pins. A high voltage (+24/+21 VDC) is pulsed onto the EPROMS
program-pin. It also has adress-pins and data-pins. Like ROMs, EPROMs come in variable sizes.
PROM is Programmable Read-Only Memory". This chip can not be erased. It has no window.
RAM means Random Access Memory and is the chip in your computer used to store various stuff
on. It can be read-from and written-on infinite times. Do not confuse this with ROM, or your
Hard Disk as some people do. For now, it has nothing to do with this FAQ.
The "ROM-image" is (a grab from) the game-code (-data/program/software) from
the actual ROM from a game. Game Emulators use these. It is produced (programmed) and stored
on the computers used for development (Apple ][ back in the days) of the game.
The images are then manufactured (not burned !) right into the chip in the factory.
Once the chip has been made and the code is on it, the ROM can only be read. It is write-protected,
like a Compact Disc.
ROMs come in variable Byte sizes, since not every game uses the same space.
There are 2K (2 KiloByte), 4K, 8K, 16K and even 32K games (Fatal Run).
Carts and games for the 2600 that carry EPROMs inside are Loaner Cartridges and Prototypes, as
well as games with limited quantities like CubiColor and Okie Dokie.
Some ATARI 2600 game prototypes contain two EPROMs since a single one of a large K amount was
more expensive then two half ones.
The fading away of the stored code, is what's called "bitrot".
There is not much known about this phenomenon though, and in fact there's no scientific and
official evidence yet that EPROMs will. Most manufacturers don't tell the lifespan of there
EPROMs. One official source notes that the electrically charged code will simply "leak"
out of the EPROM in 10 to a 100 years. There will be no physical damage though, and you can erase
the EPROM fully and put the image back on (if you would have it).
Some people suggest that EPROMs will erase themselves after about 20 years, and some have
indeed. Some never-before-seen O^2 games were found on a 4-in-one EPROM cart in Europe
recently, but one of the four chips had rotten away. Yet this seems more like a random act
then a form of erosion. Physical rotting of the EPROM will occur too, but that will really
take a lot of decades.
Well, if you are still worried over all this, you can preserve your EPROM in the following ways:
Perhaps, but this is all I could find out for now. Check out the
"Dissecting a Proto" for detailed pictures and technical stuff that will
scare your friends away. You can also have a look at some opened carts at the
Inside-Out page.
There are widely varying opinions on the subject, and as I already said, there are not many
documents on bitrot. For now it will remain an unsolved mystery and time will just have to tell,
like many things in life.