Activision River Raid EPROM cart scan

[CPUWIZ]

Thanks go out to Atari Rescue Group who sent this to me. I figured people might like to see what it looks like.

[Csonicgo]

[CincYnoTi]

i thought the E in EPROM meant it was Erasable because there is a little window on the ROM to erase it with UV(?) light. what kind of eprom is this one? do all the activision games with that second smaller chip visible from the outside of the cartridge have eproms inside?

 

i think i have a couple activision games where this second chip is visible.

[CPUWIZ]

Electronically

Programmable

Read

Only

Memory

 

 

This is what you call a OTP (One Time Programmable) EPROM. Most likely all the ones with another chip visible will have EPROM's inside.

 

Your thinking of EEPROM's (Electronically Erasable Programmable Read Only Memory), I think.

[Mindfield]

Actually, there's not much difference between an EPROM and an EEPROM. EPROM (Erasable Programmable Read-only Memory) is erasable by exposing it to ultraviolet light. EEPROMs (Electrically Erasable Programmable Read-Only Memory, also known as Flash EEPROM) are erasable via an electrical charge. EEPROMs are similar to flash memory with the exception that EEPROMs are slow, requiring data to be written or erased one byte at a time, whereas flash memory can be written and erased in whole blocks.

[JB]

Electronically

Programmable

Read

Only

Memory

 

 

 

This is what you call a OTP (One Time Programmable) EPROM. Most likely all the ones with another chip visible will have EPROM's inside.

Errr...

Does anyone else see the problem of a one-time progrmmable EPROM?

E=erasable.

It's not erasable if it's OTP.

...

Not that logic ever stopped anyone before...

 

I think a OTP chip should technically be a PROM(Programmable Read-Only Memory). No E means it can't be erased.

 

Your thinking of EEPROM's (Electronically Erasable Programmable Read Only Memory), I think.

EEPROMs are ELECTRICALLY erasable. No UV needed.

Only EPROMs have the windows. And all EPROMs do(or should).

[cwilkson]

Electronically

Programmable

Read

Only

Memory

 

 

 

 

Slight correction here:

 

Erasable

Programmable

Read

Only

Memory

 

EEPROM is indeed Electrically Erasable (as opposed to UV erasable).

 

Technical drivel follows...

The "glass" window in EPROMs is actually quartz...glass blocks (absorbs, reflects, neutralizes, whatever you prefer) ultraviolet light. So you can't have a windoow made of glass. It would still work, but it would take a long time to erase the part. OTP (One Time Programmable) EPROMs are exactly the same as standard EPROMs, but without the very expensive quartz window. Standard windowed-EPROMs are used for prototyping/engineering, while OTPs are used for high volume production.

 

Historical drivel follows....

In the beginning (sorta), there were ROMs. These were custom parts that were very expensive. Then you got PROMs. These were cheaper because they weren't custom designs. But they could only be used once. Then you got EPROMs. Maybe a bit more expensive, but they were reusable in different designs. Particularly useful for prototyping and long term software upgrades! Next came EEPROMs. They were quite expensive, but they could be erased electrically. They were not dependent on UV light sources, and could be erased in system, by the system itself. (Cool!) But the erase time, while much faster than UV EPROMs was linearly dependent on the size of the EEPROM. For large EEPROMs, this time would become ridiculosly large...i.e. HOURS! This led to Flash EEPROMs, (usually just "Flash EPROMs" or finally, just "Flash" memory.) With Flash, the erase time per bit is still very long (~10ms). But many bits are erased in parallel. So it might take only 10ms to erase half a megabit of memory. The downside is that you can no longer erase individual bits or bytes.

 

What's next? Maybe polymers? Ovonics? Magnetic RAM memory? Nobody knows....(not even the Shadow!)

 

-Chris

[CPUWIZ]

Yes, I know, I noticed it too late and didn't want to go back and edit it.

 

[cwilkson]

And now I just lost an entire rant, just because I wanted to preview it! I'll try to recap....

 

It looks like Mindfield and JB beat me to the punch. There are some nit-picky things, though I might not have addressed all of them. I'll just say that what I worte is pretty definitive...I design Flash Memory chips for Intel.

 

disclaimer: I do not speak for Intel Corporation. The opinions stated herein are my own and do not in any way represent the official position of Intel Corporation.

 

OTPs are indeed EPROMs. EPROMs are very different from PROMs internally. Think about it this way. Take an ordinary windowed EPROM and dip it in epoxy. It's still an EPROM, but you can't erase it because you can't get UV light onto the cells. That's exactly what an OTP is. An EPROM without the quartz window.

 

There are some big differences between EPROMs and EEPROMs, both internally and in external capabilities. E.g. an EEPROM can erase any single byte. Certainly can't do that with an UV EPROM! Regarding Flash vs. EEPROM...an EEPROM uses single byte addressing for both program and erase. A Flash memory erases in parallel to save time, but it still can only program one byte at a time.

 

Hmmm....the other post was more informative, but I think this one covers the basic points.

 

-Chris

[JB]

OTPs are indeed EPROMs.  EPROMs are very different from PROMs internally.  Think about it this way.  Take an ordinary windowed EPROM and dip it in epoxy.  It's still an EPROM, but you can't erase it because you can't get UV light onto the cells.  That's exactly what an OTP is.  An EPROM without the quartz window.

Like I said, not that logic ever stopped anyone.

 

It's still not logical that it can be an EPROM if it can't be erased.

[cwilkson]

Like I said, not that logic ever stopped anyone.

Yep. If you're looking for logic, you're in the wrong hobby!

It's still not logical that it can be an EPROM if it can't be erased.

Ah....but it can be. You just have to remove the epoxy protective layer. The same as removing the sticker from a quartz window, just a little more labor intensive!

 

-Chris