Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [eprom]

Erasable Programmable Read-Only Memory, which is a type of non-volatile memory that can be programmed by an electronic device and erased by exposure to ultraviolet light.

Erasable Programmable Read-Only Memory, which is a type of non-volatile memory that can be programmed by an electronic device and erased by exposure to ultraviolet light.

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Why am I seeing -5 V or lower on the output pins reading an Intel 1702A EPROM?

I am building a breadboard/Arduino reader to dump the data on a very old Intel 1702A EPROM chip. (data sheet) When doing some basic testing by tying all the address pins to ground, I am seeing unexpected negative voltages (between -5V and about -7V)…
BZo
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Is it safe to reconnect a presumably broken PROM connector pin?

I am trying to understand (and fix) a soda machine that doesn't seem to accept 1€ and 2€ coins while all stickers (inside and outside) seem to imply that they should work (5ct to 50ct do work). I noticed that the coin validator (class "MS 1000" by…
Imanuel
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How to generate +5 V and -9 V voltages to read an Intel 1702A EPROM via Arduino?

I have some simple experience with TTL logic and Arduino, but I'm only a hobbyist and am bit stymied by my current project, which is attempting to read the data from an old Intel 1702A EPROM. The actual reading part should be simple: set the address…
BZo
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Can an EPROM be "refreshed" without UV erasing?

I have lots of AM27C512 EPROMS (with the UV window) which are quite old (1980's.) Using a Xeltek SuperPro 3000U, most can still be read and verified. A few have failed outright and were replaced. Question: Can these be successfully "refreshed" by…
rdtsc
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EPROM data retention lifetime? Older instruments possibly due to fail?

I have EXPENSIVE old HP instruments that are from the 1980's that work great and are certainly very good instruments, completely usable in the home lab. Each has between 4 and 12 of the old UV type EPROMS that hold the program and other data used in…
ronna
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old 80C31 circuit not working. EPROM data retention issue?

I have an old piece of pro-audio gear in for repair. It dates from 1990. It was a fairly high-end piece of gear at the time and still has some value so it is worth repairing. But the symptoms I see have me scratching my head. At some point, the…
danmcb
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Switch between power and signal with MCU

I am trying to make a basic EPROM programmer using an Arduino. It is designed to programme M27c322/160/800 devices. One problem I am encountering is that these 3 devices have a couple of the pins different. For example, the A20 pin on the 322 is…
Jaska
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How to replace TTL PROMs in a design operating at 20MHz

I am attempting to come up with a reasonable way of implementing a design that was intended for cheap computer applications in the 1980s and which was originally designed to use a pair of TTL PROMs (a 28S42 and a 24S10) to control a state machine…
Jules
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EPROMs /OE switching Circuit

For a personal project I'm trying to make a reproduction of a SNES game (Earthbound) which is 3mb in size. Now the easiest way would be fitting the game in a 4mb 27C322 and multiplex the 16 bit bus to 8 bit (there are even pre-made PCBs that take…
MastErAldo
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Needing some EPROM breadboard help!

I'm currently trying to make an EPROM programmer on my breadboard capable of programming a single address at a time. Nothing fancy for writing large programs, just trying to learn some basics. Right now, I am stuck without a button to trigger a RC…
Andrew Albritton
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Looking for information spec sheet on an old PROM chip (GI 9128B-1180)

I just stumbled on an Apple II "clone" that uses a GI 9128B-1180 chip for the ROM. The curious thing about it is the wire soldered on a leg. So, my hypothesis is that they didn't have the usual part available and used this instead. I want to dump…
Z8Michael
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Problem with IC chips, Eprom and LCD Screen

EDIT: I have made the changes suggested with the &gate and the 555 timer to get the (E) enable pulse. I hooked up a debounced switch so I could walk through step by step. This highlighted some logic errors in my code. I also hooked up the R/W pin to…
Rick Dearman
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Erasing and Reprogramming old EPROMS

One of my customers brought in several old EPROMs that he wishes to be re-programmed with the current firmware their system is using. My usual way of dealing with this is to place the EPROMs in the eraser - this has a 10-minute timer. When the…
Dwayne Reid
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EPROM memory - the theoretical possibility of recovering data from memory after erasing the exposure with ultraviolet light?

I have a small question. We have a EPROM memory. Is there a theoretical possibility of recovering data from memory after deleting with ultraviolet light? Is this theoretically possible? Or maybe it is impossible? Anyone can give a source/reference…
Aurelio
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EPROM programmer voltage/signal switch

I am trying to make a basic EPROM programmer for M27C322/160/800 chips, mainly as an learning exercise since I know I can buy adaptors for programmers I already own. I found a very useful resource in the form of an old magazine article that explains…
Jaska
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