I have a bunch of old surplus used EPROMS MM2716Q-1 and TMS2516 both manufacturers exhibit the same behavior.

They all have the sticker that covers the window some have a “13” suffix and some have a “14” suffix all of the chips will erase, but only the ones with the “13” suffix will program…before or after erasure.

Weird…what’s up? Any ideas?

 

Generally speaking -- No. Parts that old are UV eraseable with a UV light of the proper wavelength and intensity(2537 Angstroms @ 35,000 μW/cm^2). WRT to your programmer there may be some problems in saying the TMS part is the same as the MM part. They are different manufacturers and likely have different programming algorithms.

 

Just to be clear...I know how to erase and program these chips.

I've been pulling my hair out all day long trying to figure out why some of them were programming and some weren't.

Then I started to notice a pattern while removing the stickers...the ones with "13" would program, and the ones with "14" would not.

 

Just to be clear...I know how to erase and program these chips.

I've been pulling my hair out all day long trying to figure out why some of them were programming and some weren't.

Then I started to notice a pattern while removing the stickers...the ones with "13" would program, and the ones with "14" would not.

Just to be clear your original question betrays a lack of knowledge about these parts.

1. So according to the datasheets you can find, what do the suffixes represent? If I had to guess they might indicate the access time for a read operation.
2. Do both the MM parts (National Semiconductor) and the TMS parts (Texas Instruments) have both -13 and -14 designations?
3. Are the pinouts of the parts IDENTICAL in name and function?

You might also tell us what kind of contents the ones that do not program have.

1. Do they remain in the erased condition?
2. Are they even close to being correct?

 

The suffixes represent nothing...nada...zilch about the chip itself...they are on the "stickers" that the original programmers placed on the chips to identify them and prevent exposure.

The chips themselves are pin for pin replaceable, but this problem has NOTHING to do with that.

And now I am done.

I just never learn.

 

Here's a thread from elsewhere that offers experience with the TMS2516. Lots of problems programming it.

https://www.eevblog.com/forum/vintage-computing/programmer-for-tms2516/25/

John

 

Some of the early EPROMs required that each cell be "hit" numerous times, and that the hits not be consecutive for any single address (i.e. typical programming would go around the full address range to be programmed many times). Unfortunately, I don't recall when that requirement disappeared. I know the 1702 was like that, but it predates the devices in question by a few years.

 

Some of the early EPROMs required that each cell be "hit" numerous times, and that the hits not be consecutive for any single address (i.e. typical programming would go around the full address range to be programmed many times).

Until 2764, each address was programmed with a single 50ms pulse. The algorithm was changed on subsequent parts to keep programming time from doubling every time capacity was doubled.

There were a number of variations on the closed loop algorithms. All of them verified the address being programmed before going to the next. Any address that failed to program in some number of attempts would result in programming aborting and the device being rejected.

 

The suffixes represent nothing...nada...zilch about the chip itself...they are on the "stickers" that the original programmers placed on the chips to identify them and prevent exposure.

The chips themselves are pin for pin replaceable, but this problem has NOTHING to do with that.

And now I am done.

I just never learn.

You did not exactly make that clear in your original post, that the -13 and -14 were on the stickers and not on the part itself. Why would the marking on the stickers have anything to do with being able to program the chips??? I can only conclude that you are drawing erroneous conclusions from shaky premises.

 

You did not exactly make that clear in your original post, that the -13 and -14 were on the stickers and not on the part itself. Why would the marking on the stickers have anything to do with being able to program the chips??? I can only conclude that you are drawing erroneous conclusions from shaky premises.

Doesn't seem that unreasonable to me. Batch/lot numbers, etc. maybe.

The original question was whether or not these chips can be configured to no longer be programmable. Some microcontrollers have such a capability. I forget the name, but it's got the word fuse in the name. When you're programming the chip, you have the option of burning the fuse - once that's done, you can't reprogram the chip again.

I have no idea if the chips the thread starter is asking about have a similar capability, but I can understand why someone would ask the question. Assuming that such a feature did exist, the stickers might represent which programming configuration had been installed... including the possibility that some were locked and others were not.

 

I have no idea if the chips the thread starter is asking about have a similar capability, but I can understand why someone would ask the question. Assuming that such a feature did exist, the stickers might represent which programming configuration had been installed... including the possibility that some were locked and others were not.

All EPROMs in ceramic packages with quartz windows can be erased.

In later generations (larger capacities), manufacturers started implementing spare arrays as a means to increase die yield. IIRC, these were sometimes swapped in by using EPROM cells to to remap column or row addresses. These addressing cells were covered by metal or other layers so they wouldn't be erased with the rest of the array cells.

In other types of products (e.g. SRAM, DRAM), they used fuses because EPROM requires a second polysilicon layer which is only present in EPROM, EEPROM, FLASH technologies.

 

Doesn't seem that unreasonable to me. Batch/lot numbers, etc. maybe.

The original question was whether or not these chips can be configured to no longer be programmable. Some microcontrollers have such a capability. I forget the name, but it's got the word fuse in the name. When you're programming the chip, you have the option of burning the fuse - once that's done, you can't reprogram the chip again.

I have no idea if the chips the thread starter is asking about have a similar capability, but I can understand why someone would ask the question. Assuming that such a feature did exist, the stickers might represent which programming configuration had been installed... including the possibility that some were locked and others were not.

Those chips (2716's ca. 1977) were among the first EPROMS (ca. 1971), successors to the 1702 and the 2708, and no they did not have the feature the TS was asking about.