KLund1 wrote on 2024-03-11, 05:06:

I have a large stash of a couple hundred 27xxx eproms
My T866CS or TL866 II Plus programmers can not read or program any of them.

Old EPROMs require high programming voltage, 25V or 21V. You'll need older programmer, not easy to find at reasonable price - and many are not supported anymore so you'll have to build a PC with specific OS (Win9x, maybe even DOS) to get them working. That's assuming you get the programmer and software for it, since just the HW might be useless if the manufacturer refuses to send you the software.

Alternatively some new "pro" series programmer, possibly with the required adapters for these parts, which will be anything but cheap. These days they ask 1k EUR for the base, then extra for adapters (and they make them in such a way that, to support multiple chips, you'll need a box of adapters). And there's the software costs, possibly some monthly payments, to add to that. Not really an option for private use.

KLund1 wrote on 2024-03-11, 05:06:

Also I could use some education on the suffixes -2, -20, -200 I get as 200ns. But what do DC, A, P, DA, Q, AFI, JL, etc mean?

Vendor-specific. Usually the letters are important for ordering parts - these will be different for the package type (these old EPROMs are probably all DIP but some might be plastic and some ceramic), temperature range and/or use case (commercial, industrial or automotive), possibly internal chip revision or even what factory made these (since the process differences can sometimes matter).
In general, for programming purposes, you don't care about these as long as the pinout and package type is correct. Except maybe two things:

- Letter A at the end (2732 and 2732A for example) usually means improved design, possibly lower voltage and shorter programming pulse is required. A programmer that supports only A chip in the family might not be able to program non-A variant, or the chip will not be reliable long-term (weak write). The other way around the lifespan of A chip programmed with non-A method might be shorter, or even damage might occur due to voltage being too high. Or it could end up with such a strong write that it'll become pretty much un-erasable via UV (the amount of UV needed to clear the cells will also cause permanent damage to the structure).

- Letter C between 27 and the size number denotes CMOS chip. Just like A it will be newer, faster variant with less power usage and probably lower programming voltage.

Some of those chips are in the support list for the T56. Others may work using an equivalent part number, especially for reading. I see no reason why 27xx parts wouldn't be readable in most any programmer, even if there is an ID mismatch or whatever. When it comes to writing you can't always find enough info to know which parts are truly equivalent, so there is no guarantee in that case. Chips without a UV window are One-Time-Programmable and can't be erased if they've already been written.

Thanks for the reply
Most appreciated
But still looking for a burner that will work.
Also read. Guessing is not the best way to work with eproms, I would think

Here:
https://www.eevblog.com/forum/blog/eevblog-41 … 009/#msg3946009

For those that need to program 21v devices on the TL866II+, you can simply add a 10k resistor between pins 5 and ground (or pins 5 and 4) of U3 via a removable jumper . This is effectively changing the voltage divider of r8/r9 which sets the output voltage . This will give you an approx 3+ volt additional range and thus give you 21v when the programmer is set to 18v. Removing the jumper, returns the programmer to normal. This allows me to program old 2764D's (that use 21 volts vpp).

Edit: You can achieve 25v VPP (in addition to 21v) by using a 6.2K or 6.8K resistor instead. This gives a +7volt boost to the vpp voltage as viewed on the application.
For example to get 21v, you set the programmer vpp to 14volt (14 + 7=21), for 25v, you set the programmer to 18v (18+7=25)

Thanks,
That is a little more involved than I would prefer.
Is there a unit I could just purchase to do that I am asking about?

Check out Willem EPROM.

WOW! Thanks for that!
Very cool unit.
But my Main rig does not have a printer/parallel port
Also not that simple to use. dip switches and voltages ?
I'd kill every eprom I have just to find the right settings. Or am I missing something. And the printer port is an issue.

Yeah. It requires a native lpt port (a PCI card will not work). The software is for win9x - xp. The dip switches and voltage jumpers are simple - the software shows you the correct combination for each rom type.

XGecu T48 and T56 does : "Suppport high-voltage chips, VPP Maximum up to 25V, that is what TL866II cannot achieve."
Also for TL866II you can supply the needed DC level from batteries (or other well regulated/filtered source) to the VPP pin (you bend it up gently so not in socket), saw a good youtube about it....

Cool !!
The T48 looks about right. I checked the parts link for that. It seems to cover almost all the chips above.

But there what seem to be prices all over the place. Most from Ali-Express. The $15.00 ones I would assume are fakes. The, what looks official, the LRF site, has it for $40, but charges $45 to ship to me on the west coast.
Where could I get REAL one for a reasonable price? Just the unit. I do not need all the accessories.
Thanks everyone for all the input !

There is a XGECU official store on AliExpress , it is your best bet other than the official resellers they list on their website

https://www.aliexpress.com/store/4805043

The original TL866 (A or CS, not the TL866 II Plus version) can do 21V without mods, but it's also considered old now and not supported anymore. And it has other limitations like 3.3V I/O so that some modern chips with 1.8V I/O need active adapters. Even the "old" TL866 can't do really old chips like bipolar PROMs for example but then again this is a very specific need that most people won't have.

This new XGecu T48 seems to resolve all these problems (up to 25V Vpp, 1.8V I/O, USB2 for faster operation on high-capacity chips) but I bet the software is still kinda wonky. If it works it works, but good luck if it doesn't. I still remember how TL866 drivers messed up all my virtual COM ports, in the end I had to get an old laptop to be a host for TL866 so that it doesn't pollute my work environment. I could try a VM and USB pass-through I suppose. But you can't argue with the price, if I was buying new EPROM programmer today I'd be looking at T48, or maybe T56 (although I don't do modern Flash chips).

Speaking of software from China... let's just say bugs and Engrish are not the only things to be worried about. For anything commerial I'd suggest a separate machine to host the programmer - just to be on the safe side.

Thanks everyone.
Yes the software is odd. but it works with my two 866's. But I have to use a different version for each one.
I went to the link above and with one of those coupon finder extensions was able to get it for 43 shipped.
I'll report back after it arrives and after I test a few of these old chips.
Thanks again. All very much appreciated !

There's a command line linux software package for the TL866II but I forget the name.