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Forum Index : Microcontroller and PC projects : MM2/+ EPROM Programmer? (Old skool)
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GoodToGo! Senior Member  Joined: 23/04/2017 Location: AustraliaPosts: 188 |
Howdy chums, I have a requirement to read and burn a few old skool EPROM's and PROM's to assist in the fixing up of some old 1980's arcade boards. While my trusty Wellon VP-280 has performed beautifully in the past, I'm having issues with it not being able to read certain PROMs. (eg. 82S129, 82S123, 2716, CY7C291A, etc.) Looking at the datasheets for the above IC's, I can't see why a MM2 (or more likely a MM+) couldn't do a similar job. Has anyone got any hints or tips or thoughts or ideas on this? Cheers, GTG!  ...... Don't worry mate, it'll be GoodToGo! |
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Quazee137 Guru  Joined: 07/08/2016 Location: United StatesPosts: 593 |
The I2C way 3 PCF8574's 16 address 8 data or two 74HC590 for address and a PFC8574 for data or two 74HC590 as address but use the 170 pins 2,3,4,5,6,7,9,10 as port for data. (use 8 bit level shifter for 5V to 3.3V) pin 14 for your read pulse pin 15 to reset the counters pin 16 as eprom output enable reset counters to 0 then use your read pulse to count up as you read It could expand into a reader/programmer/copier the 5 volt buck modules make the PGM voltages easy. |
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| GoodToGo! Senior Member Joined: 23/04/2017 Location: AustraliaPosts: 188 |
Okay, After mulling it over for a while (and thanks Quazee for the tips!) I decided to have a go using my E100, Grog's expansion/prototyping board, a 5v-to-whatever boost converter for the supervoltage and a dual relay module for supervoltage switching. Cobbled together, I ended up with this mess....  and a close-up....  The E100 had plenty of 5v tolerant pins for this application, and direct wiring it made the software side of things a lot easier. One thing though, because I am using pins 66 and 67 on the E100, I had to remove the plug-in RTC module from it, because it was pulling both pins up to 5v. (Made two of the data lines all screwy and took me longer than I care to admit to figure it out) Even though the EPROMs I'm using (Cy7C291 and Cy7C291A) are 2kx8, For the application I needed them for, I only required 256x4. (82S129 replacement). So I dispensed with the A8-A10 address lines. (grounded them) Lots of chip swapping for reading/writing/erasing/blank checking meant that invariably I was gonna stuff up. And I did. Reading the datasheet, you must have 5v Vcc applied before applying the 12.5v or 13.5v (depending on the IC) supervoltage. I killed two chips stonedead because I forgot to reconnect Vcc during development. They both got stinking hot and also caused the E100 to reset! So I connected the EPROM Vcc pin back to pin 80 on the E100 as a monitor. My quick and dirty test program now checks for Vcc before it does anything. That solved that little issue. (and also eliminated the non '-A' variant of the chip from my stock.  )So now I can reliably program and read these nice little EPROMS from the early 90's. The next step is to work out how to get the program to load a file and use the contents to burn the chip. Oh, and chicken-scratching out a schematic, or even get a proper pcb made up. These Cypress UV EPROMs differ to normal UV EPROM's when it comes to blankchecking. Normal UV EPROM's erase to all "FF"'s. These don't. You have to configure the chip a certain way and check for zero's instead. If anyone is interested in the 'proof of concept' code, I'm happy to post it. Cheers! GTG! ...... Don't worry mate, it'll be GoodToGo! |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 593 |
A few..... years back a buddy got a bunch of an old arcade systems and wanted to restore them. He sent me a box of rom/proms/eproms/rams of many types and data books on most of them. I ended up using dip switches and leds on I think it was eight or nine bread boards.Along with my very old EP-1 V2.05 6/23/88 I safely was able to save all of them to CD. The EP-1 DOS software was long gone. But lucky this was the type where the computer program was mostly for making file operations easy. All the real work is in the EP-1. A USB to RS232 with a 9 to 25 adapter got it working under ubuntu with a few bash scripts. It was a fun few weeks. Heres hoping your having the same kind of FUN. |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 593 |
A few links that I hope you find useful. Bi-polar proms 4 sell Bi-polar proms 4 sell bi-polar PROM replacement kit Arcade Manual Archive on 4 DVDs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5091 |
Maybe this is of interest too, when restoring old games. http://www.retroclinic.com/leopardcats/galprom/galprom.htm Volhout PicomiteVGA PETSCII ROBOTS |
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