School me on programming eeproms for my Vs board

smalltownguy2

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I need a little help on programming eeproms for my Vs boards.

I've been able to program the 2764 roms no problem for games like Tetris, SMB, etc.

Now I've got a Vs Top Gun / Castlevania daughtercard, and it has a D27C1001D-15 eeprom on it. My Neehams EMP-10 doesn't really want to program it properly. It throws an error at the very end. I have a setting for a 27C1001A, but not a 27C1001C.

I also have a TOP2005 programmer, and it throws the same error.

Can I purchase and substitute a 27C1001A eeprom for my needs? I'd like to program 2 of them; one with Top Gun code, and the other with Castlevania. Then I can just swap the chip when I want to play one or the other.

Am I on the right track here? Are there other eeproms I can get that should/would be easier to program?
 
Bump.

I purchased some replacement 27c010 eproms Sunday, and they should be here soon. We'll see if they accept programming.
 
You need to be careful with 1Mb EPROMs, there are two pinouts, JEDEC and non JEDEC and they couldn't decide on a naming standard. What one manufacturer calls a 27c1000, another manufacturer call 27c1001, or 27c100, or 27c101. You really need the data sheets of the exact chip to know what you actually have.
 
You need to be careful with 1Mb EPROMs, there are two pinouts, JEDEC and non JEDEC and they couldn't decide on a naming standard. What one manufacturer calls a 27c1000, another manufacturer call 27c1001, or 27c100, or 27c101. You really need the data sheets of the exact chip to know what you actually have.

Thanks. The chip I was working with was an NEC chip, and it was labeled 'D27C1001D'

The closest setting on my programmer was for a 27C1001A. I tried that, but no go. Then I tried the 27C1001 setting, no go. Then I tried other manufacturers, and no go. Lastly, I tried 27C010. No go.

I think I might have found a crappy datasheet here:

http://www.buyicnow.com/files/datasheet/EPROM/716.pdf
 
That datasheet isn't much use, you need to find the datasheet for the manufacturer who made the eproms you are using and compare the pinouts to the chips you are planning to use to confirm they are the same pinout. This is only an issue with 1 megabit eproms, and very ole 2716 eproms. Thats the only times the industry got itself in a tangle over naming standards.

So you need the NEC datasheet, and you need to select the NEC 27c1001 option on your burner if there is one. Don't worry about the A or D, it doesn't matter from an external user perspective. You also need to confirm the programming voltage (often written on the eprom itself) is chosen correctly by the programming application, its possible this is not set correctly and the chip is failing to verify. If the burner is chosing a different Vprog you will need to adjust in the in application. You need to do this with any eprom you burn really, especially if the application is a bit vague regarding its settings or doesn't have the chip you are using listed as an option. Get the voltage too low and it will either fail or do a bad write, get it too high and the quick will be blown.

Another possibility is that you hadn't fully erased the chip properly before putting it in the eprom programmer and it is failing the verify stages. A blank chip contains all binary 1s, the programmer can only convert a 1 to a 0 as required, if any loci are already 1 it cannot convert them back to zeros, so writing to a non-blank chip is basically a "merge" not a clean write. If the UV erase step is not complete then some loci will still be zero and the chip will happily write but fail the verification step.
 
Thanks for the helpful info. I had the chip in the UV eraser for 10 minutes at my last try. Is that enough, or should I be leaving it in longer?

FWIW, it's verifying as 'erased' with my eprom programmer...
 
If it passes the blank check then it should be ok, your programming voltage is probably not set correctly.
 
It's unlikely, but possible, NEC ROMs are pretty much bullet proof, unless they are plugged in backwards or given too high a vProg.

Or you have a fault with the burner that only affects larger chips, eg dirty ZIF socket contacts on the higher pins.
 
Nope, program verify error.

CIMG6201.jpg
 
Try another chip is all I can suggest, if you are buying new ones you need to ensure they have the same pinout as this one, you cant just go by the 27c1001 description unfortunately. If you stick with NEC you should be fine.
 
Success! My new 27C1001 eproms arrived today. They programmed correctly on the first try. Must have had a flaky eprom.

Top Gun pcb...converted to......

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