EPROM Chip doesn't have a window?

[Keudn]

I am messing around with an old Alphasmart Pro and it has a AM27C256-200PC EPROM chip that is clearly documented to be "EPROM" and even says it printed on the board, however there isn't a window on it to erase it with. Can someone with experience with old technology know what is going on and if this chip is erasable?

[iamdarkyoshi]

datasheet says it is UV erasable... odd.

[Wferr]

it might be all done internally

[Keudn]

datasheet says it is UV erasable... odd.

I know but the top and bottom of the chip have no window on them whatsoever, im confused  :wacko:

[iamdarkyoshi]

and there is no sticker on it?

[Keudn]

and there is no sticker on it?

Well there was a sticker on top saying alphasmart and then the version of ROM on it but i ripped that off to see the model number underneath it

[iamdarkyoshi]

Well there was a sticker on top saying alphasmart and then the version of ROM on it but i ripped that off to see the model number underneath it

odd. You could use the igniter sparker from a lighter, but although it would be erased, it probably couldn't be written to again

[Stefan1024]

In the datasheet it says you need a powerful UV lightsource to erase the chip. You can erase directly througth the plastic housing.

Not sure if a few hours of direct sunligth on a sinny days is enougth. But it's worth a try.

[Keudn]

odd. You could use the igniter sparker from a lighter, but although it would be erased, it probably couldn't be written to again

Lol well my intentions were to mess around with with since it has a 68k processor and see what I could do with it, although I probably don't have the knowledge to actually do anything with it

[Keudn]

In the datasheet it says you need a powerful UV lightsource to erase the chip. You can erase directly througth the plastic housing.

Not sure if a few hours of direct sunligth on a sinny days is enougth. But it's worth a try.

Hm might as well try it, on a slightly unrelated note how do I rewrite to it lol

[Stefan1024]

Hm might as well try it, on a slightly unrelated note how do I rewrite to it lol

You have to follow the routine and timeing in the datasheet. If the EPROM is connected to the CPU you can write a program to do it.