Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
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factory:

--- Quote from: bd139 on July 15, 2022, 07:01:11 am ---Well spotted. I was clearly asleep when I wrote that. It’s a 74S287.

Trying to locate something which is both available and has programming data sheets and isn’t extortionately priced. The Tesla MH74S287 actually looks the best bet at the moment.

Have opened a case with the seller of the original part now. Their service and communications are terrible so I’m just claiming it back via eBay now. They’re disinterested in dealing with it or sending another part out and are pushing back asking to give it another couple of days after it has been missing for two weeks now on a RM 24h delivery I paid for. So screw them. User test-equip forget it. Shame because they have a lot of tek and HP parts.

Edit: if anyone has that ROM (U1605 on vertical amp board) on a scrap 465B and are willing to part with it I am interested so I don’t have to futz programming a ROM for it :)

--- End quote ---

I think Med said he might have one on a parts board, but it probably got missed amongst the general OT noise.
If you go for programming a 74S287, you should get a couple, as I had several duds amongst the clone 74188 I used to repair one of the 5340A counters here, even sent me two used ones (in the batch of 20) with code already on them.

David
bd139:

--- Quote from: factory on July 15, 2022, 01:40:36 pm ---I think Med said he might have one on a parts board, but it probably got missed amongst the general OT noise.
If you go for programming a 74S287, you should get a couple, as I had several duds amongst the clone 74188 I used to repair one of the 5340A counters here, even sent me two used ones (in the batch of 20) with code already on them.

--- End quote ---

I shall wait to see if he comments :)

Good call on getting a few. I was expecting to get used ones if I ordered some from China. There are 10x NOS MH74S287's which look reasonable substitutes for the money. They also have programming documentation which is useful.
Vince:

--- Quote from: bd139 on July 15, 2022, 01:32:54 pm ---Hey it's HP. Doesn't matter which side, I'm sure we appreciate it. Apart from med  :-DD

Edit: so the whole blowing a PROM thing lead to a rabbit hole where I found the schematics for my old Z80 SBC I built when I was 12 which I never really liked. Mulling ideas around a 6502 variant with FORTH as a bench utility computer. Can probably put one together for less than the price of a BBC at the moment which have reached extortion value. And of course incur hours of glorious fettling.

--- End quote ---

Oh I misunderstood... thought you had your childhood BBC computer still with you, albeit inaccessible packed somewhere.... if you have to buy one of course it's not very interesting financially...

I guess any 8 bit micro would be plenty enough to make a programmer here... aren't they any available in the UK at all ?!  :-//
You said you have a programmer for PIC chips is that it ? Can't one buy a PIC MCU currently ?! Has it gotten that bad ?!
I mean could be, I don't know... haven't tried to buy an MCU recently....

Honestly if getting something done with a micro of any sort, is that much trouble.... for only 256 memory locations to program, I would just do it by hand ! :-//

Just put an 8 bit counter to drive the address pins, that you can increment with a push button (or just put a couple coding wheels). Maybe add LED 7 segment displays to it so you can make sure the address bus is indeed at the intended location, then put a coding wheel or dip-switches on the 4 bit data bus and just flick through the 256 memory locations, shouldn't take all that long to program even by hand  :-//
Maybe add displays to the data bus as well, so you can then read the PROM to make sure it's been programmed properly.

It's a one-off thing, it only needs to let you program THAT particular chip, and do it once, maybe twice if unlucky the first time, but that's about it...

It's not like you were trying to make something fancy that's universal and super convenient and quick to mass program these because you want to flog them on Ebay by the hundreds... you only need to get that one job done, no more,  that's all...

AVGresponding:

--- Quote from: bd139 on July 15, 2022, 01:32:54 pm ---Hey it's HP. Doesn't matter which side, I'm sure we appreciate it. Apart from med  :-DD

Edit: so the whole blowing a PROM thing lead to a rabbit hole where I found the schematics for my old Z80 SBC I built when I was 12 which I never really liked. Mulling ideas around a 6502 variant with FORTH as a bench utility computer. Can probably put one together for less than the price of a BBC at the moment which have reached extortion value. And of course incur hours of glorious fettling.

--- End quote ---

Motorola 65xx series fanboy eh..? Maybe buy an Amiga or Atari ST instead of a BBC, probably cheaper and certainly far more capable.



Here's a yt pick for a change:

mnementh:

--- Quote from: bd139 on July 15, 2022, 08:01:39 am ---
--- Quote from: bd139 on July 15, 2022, 07:01:11 am ---Have opened a case with the seller of the original part now. Their service and communications are terrible so I’m just claiming it back via eBay now. They’re disinterested in dealing with it or sending another part out and are pushing back asking to give it another couple of days after it has been missing for two weeks now on a RM 24h delivery I paid for. So screw them. User test-equip forget it. Shame because they have a lot of tek and HP parts.

--- End quote ---

Replying to self - eBay decided in favour of me almost instantly. Refund on the way. Good job as always  :-+

Discovered recently that due to the chip shortage, the availability of shit Arduino clones is pretty bad and the prices have gone through the roof. Considering buying the last decent "on device programmable microcontroller and electric swiss army knife" at the moment, the BBC Micro  :-DD. That and the user and printer ports give you a 6522 VIA worth of IO to play with, BASIC, assembly support and decent documentation...

--- End quote ---
What are SAMD21 boards running on your side of the pond? QT-Py is still 8 bux over here.  :-//

mnem
 :-/O
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