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ortek_service · 21st Aug 2022, 3:37 am

Yes, Chris, it was good to hear you'd now got this all working OK.

I recall initially 'scoping the Dataman-Pro (Elnec re-badge, and one of very few that supported the Tesla PROM's), to verify its programming method against the somewhat vague info on programming these.
And having to a bit cunning with shunt-diode + pull-up, to have level low-enough to fool it into attempting to program a location, but high-enough to be able to see how long it then held it hard to ground for
- As had initially discovered that it was being 'intelligent', and reading the bits first, to decide whether they needed to be programmed (unlike most EPROM programmers, that just always program, then verify after each pulse).

It was also surprising that Elnec had opted to just have one long 45ms pulse, rather than trying multiple shorter ones, for quicker speed / less heaing, and only one attempt at a location (before completely aborting prog. sequence. - with retrying option going right back to start - although fortunately it then skipped all those locations that had previously programmed OK and read correct)
It seems they'd done something similar for NS-Proms, as I recall previously having one that kept failing at many locations, so had to repeat the sequence many ten's of time, till it eventually-programmed. So maybe their programmability declines with age / that was from a rogue batch.

I never found a common programmer that supported the TI SN74Sxxx 4bit PROM's (Only 8bit ones) - Neither original (Advantech-design) Dataman 48 or the (Elnec-design) Dataman 48-Pro ones (which both do NS ones), to see what they did. So even if you could still get hold of TI PROM's, programming them could be difficult (although it seems Tesla algorithm is so similar, then can use one for that).
It doesn't seem that Tesla just copied TI devices, as there never was a SN74S571, only the '287. Although they did use virtually the same programming recommendations / odd inverted-programming arrangement (With the NS ones seemingly a bit more conventional, even if higher 10V etc. voltages were still needed to be applied).

As NS ones are now getting very hard to obtain, with previous NOS's being exhausted, then Tesla ones seem to be only alternative - especially as 8bit PROM's / parallel (E)EPROM's all tend to be in packages that are too large to make neat adapters for.

21st Aug 2022, 3:37 am	#9
ortek_service Octode Join Date: May 2018 Location: Northampton, Northamptonshire, UK. Posts: 1,440	Re: Tesla Programmer Yes, Chris, it was good to hear you'd now got this all working OK. I recall initially 'scoping the Dataman-Pro (Elnec re-badge, and one of very few that supported the Tesla PROM's), to verify its programming method against the somewhat vague info on programming these. And having to a bit cunning with shunt-diode + pull-up, to have level low-enough to fool it into attempting to program a location, but high-enough to be able to see how long it then held it hard to ground for - As had initially discovered that it was being 'intelligent', and reading the bits first, to decide whether they needed to be programmed (unlike most EPROM programmers, that just always program, then verify after each pulse). It was also surprising that Elnec had opted to just have one long 45ms pulse, rather than trying multiple shorter ones, for quicker speed / less heaing, and only one attempt at a location (before completely aborting prog. sequence. - with retrying option going right back to start - although fortunately it then skipped all those locations that had previously programmed OK and read correct) It seems they'd done something similar for NS-Proms, as I recall previously having one that kept failing at many locations, so had to repeat the sequence many ten's of time, till it eventually-programmed. So maybe their programmability declines with age / that was from a rogue batch. I never found a common programmer that supported the TI SN74Sxxx 4bit PROM's (Only 8bit ones) - Neither original (Advantech-design) Dataman 48 or the (Elnec-design) Dataman 48-Pro ones (which both do NS ones), to see what they did. So even if you could still get hold of TI PROM's, programming them could be difficult (although it seems Tesla algorithm is so similar, then can use one for that). It doesn't seem that Tesla just copied TI devices, as there never was a SN74S571, only the '287. Although they did use virtually the same programming recommendations / odd inverted-programming arrangement (With the NS ones seemingly a bit more conventional, even if higher 10V etc. voltages were still needed to be applied). As NS ones are now getting very hard to obtain, with previous NOS's being exhausted, then Tesla ones seem to be only alternative - especially as 8bit PROM's / parallel (E)EPROM's all tend to be in packages that are too large to make neat adapters for.