Programming a 2764K EPROM with TL86II

[Kepler]

Hi all,

So my TL866 has finally arrived and I have bought a 2764K EPROM from a "reputable supplier"...all in order to burn Tricky's Test ROM.

I have downloaded and installed the Xgpro v12.66 software. I can select the ROM image and it's contents appear in the left window. My question is, what do I do next? The software doesn't auto detect my 2764 and it doesn't seem to be present in the drop down lists - although there are hundreds of them. The closest I have found is the AM2764A. If I try a "Read", I receive:

Pins Detected Passed!
Check ID Error!

As I only have one 2764, I don't want to to ruin it.

Any advice?

[KenLowe]

The TL866II software complaining because the ID read from the EPROM doesn't match the ID for the EPROM type you've selected. This is not normally an issue, as pretty much any 2764 will do, and you can basically select to ignore the ID check.

If you want to play it safe, then use the software to read the ID from the EPROM, and then check it against this list:

https://ctrl-alt-rees.com/2022-07-03-ep ... -list.html

You can then select the correct EPROM in the TL866II software to match the actual ID of EPROM you have.

[Kepler]

Thanks. I couldn't find the one in the link in Xgpro so I opted for my initial choice. I then selected "Prog" and Program in the dialog box. Unfortunately, all I then received was:

Pins detected passed!
Programming Flash...
Error! Address:0x00000...
Programming...Failed.

Is there something else that needs to be configured?

[Ronin47]

Do you have a photo of the markings on the ROM? Might help us identify.

Also I would suggest you start with a clear buffer and try to read the ROM and see if it is already programmed with something else.

If not you may need to erase it first, that is if it is an erasable device?

Again a photo may help.

Personally I try to get only erasable ROMs (Either electrically or with UV) as there is a path back if you get things wrong.

Also, I'd suggest trying to find a datasheet for the ROM and confirm that you have the correct programming voltage set. There are some older ROMs that the TL866 can't handle due to the voltages required.

[Kepler]

Sure. Here you are...

[Ronin47]

Sure. Here you are...

Pretty sure that is a Mitsubishi part, so that should help you find the item from the list in the burner software.

I suspect it isn't blank so use the software to do a blank check.

Personally with used ROMs I like to erase them before I use them, but you'll need a UV eraser to do that. They are pretty cheap to buy from places like eBay and Ali Express.

[Kepler]

Thanks. I bought the EPROM from a seller who said they were blank but I will check.
Also, can you confirm that Tricky's Test ROM will fit on this EPROM?

[guesser]

Pretty sure that is a Mitsubishi part, so that should help you find the item from the list in the burner software.

Yup, and the programming voltage is 21V (not 12.5 like the AM2764A)

[1024MAK]

Keep in mind that for an EPROM, blank actually means every memory location should return 0xFF (255).

If the programming voltage is too low, the EPROM chip will be unable to flip the appropriate bits from 1's to 0's. Hence when the programmer checks the just written memory location, the result returned will not match the expected value. Hence the error...

As well as the programming voltage (VPP), the normal supply voltage (VCC) is raised to 6V during programming. BTW, you will see 'burning' used instead of 'programming' in many places.

Datasheet attached for the M5L2764K EPROM

Mark

[Ronin47]

Pretty sure that is a Mitsubishi part, so that should help you find the item from the list in the burner software.

Yup, and the programming voltage is 21V (not 12.5 like the AM2764A)

That would definitely be an issue for sure.

[Ronin47]

Thanks. I bought the EPROM from a seller who said they were blank but I will check.
Also, can you confirm that Tricky's Test ROM will fit on this EPROM?

The 2764 is 8K, so you need to check the ROM file size to see if it will fit.

Also, if for example the ROM file is 4k, you'll likely need to make an 8K file containing 2 copies of the ROM.

If it's 8K you're good to go.

[Kepler]

Sure. Here you are...

Pretty sure that is a Mitsubishi part, so that should help you find the item from the list in the burner software.

I suspect it isn't blank so use the software to do a blank check.

Personally with used ROMs I like to erase them before I use them, but you'll need a UV eraser to do that. They are pretty cheap to buy from places like eBay and Ali Express.

Unfortunately, I don't have that particular type in the list under Mitsubishi.

[1024MAK]

It's easier to search for 2764 then see if an Intel 2764 is listed (NOT a 2764A) If that has VPP @ 21V and VCC @ 6V, try that.

Oh, one thing I forget to say earlier. These older EPROMs don't actually have any ID storage. This is a feature brought in later on.

Mark

[Ronin47]

It's easier to search for 2764 then see if an Intel 2764 is listed (NOT a 2764A) If that has VPP @ 21V and VCC @ 6V, try that.

Oh, one thing I forget to say earlier. These older EPROMs don't actually have any ID storage. This is a feature brought in later on.

Mark

That's a very good point, often these ICs will program correctly when using other IC specs. As long as they match what the Mitsubishi IC needs from the datasheet.

I have a load of 27C256's that don't appear in the list, but work perfectly fine when I use a generic spec item as the template.