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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old Yesterday, 4:25 pm   #221
retromit
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Default Re: Commodore PET 2001 voltage regulators

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Originally Posted by SiriusHardware View Post
Tim also asked if he should continue using the UD5 (Basic Toolkit) PROM following on from its successful pin graft - I don't see why not, unless the running temperature alarms you.
I decided yesterday to install this in the PET, and it looks to be working correctly. The SYS command sets everyting up, and the commands are all available. So that's good news. In view of the repair, and with a couple of the other legs on the PROM being a bit wobbly (although it is now in its own socket), I might still create an EPROM for this. There was a lot of corrosion on the legs, so it might be a safer option as well.
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Old Yesterday, 4:54 pm   #222
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Default Re: Commodore PET 2001 voltage regulators

Running the test EPROMs for long periods of time will give you a fair idea of how warm EPROMs will get if you clone the PROMs into them - probably not very warm.

Unfortunately the specific EPROMs which replace those PROMs (TMS2532) are quite expensive and most device programmers don't support them, although the first adaptor you made -may- allow a programmer which can program a 2732 to programme a TMS2532 by rearranging the pins appropriately. You'd need to be very sure you had the right adaptor for the right purpose otherwise you'd risk applying the high programming voltage (VPP) to the wrong pin of your expensive TMS2532s.

My old device programmer can natively program the TMS2532 so that's another option for you as and when you get to that point. I don't have any though, so you'd need to send some down to me.
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Old Yesterday, 5:12 pm   #223
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Default Re: Commodore PET 2001 voltage regulators

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Unfortunately the specific EPROMs which replace those PROMs (TMS2532) are quite expensive .....
Would these be any good?

https://www.ebay.co.uk/itm/222249893...oAAOSw4shX2ljs

As everyone is aware I know little about these things.

Alan
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Old Yesterday, 5:26 pm   #224
SiriusHardware
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Default Re: Commodore PET 2001 voltage regulators

They might be, although that description is unpleasantly mangled as it has '27C256' (a completely different device) right in the middle of the description line. Unfortunately while my programmer can definitely programme the TMS2532 it doesn't support the Hitachi version, someone else's programmer may do so though.

The pinout looks OK, with A11 in the right place (on pin 18).

https://www.jrok.com/datasheet/HN2532.pdf
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Old Yesterday, 5:44 pm   #225
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Default Re: Commodore PET 2001 voltage regulators

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They might be, although that description is unpleasantly mangled as it has '27C256' (a completely different device) right in the middle of the description line.
Yes I can see how that's a concern. I suppose the fact that the advertised devices have 24 pins is of some comfort. I think the DIP 27C256 has 28 pins. Could always query the discrepancy with the seller before ordering.

Alan
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Old Yesterday, 5:47 pm   #226
SiriusHardware
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Default Re: Commodore PET 2001 voltage regulators

In the interests of science, I have ordered some. Although my programmer has no specific support for the Hitachi device I'm wondering it it will 'just work' if I just select the Texas TMS2532 and try programming one of the Hitachis that way, as long as VPP is the same.

They'll be handy to have if it works, there are quite a few old 80s computers which use 24 pin PROMs with this pinout.
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Old Yesterday, 5:49 pm   #227
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Default Re: Commodore PET 2001 voltage regulators

Brave!
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Old Yesterday, 5:51 pm   #228
SiriusHardware
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Default Re: Commodore PET 2001 voltage regulators

Or stupid, possibly. Time will tell.

On a brief read through the respective data sheets both use VPP of +25V and both use a 'standard' programming pulse (low on pin 20 for 50mS) so it looks quite hopeful.

Last edited by SiriusHardware; Yesterday at 6:06 pm.
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Old Yesterday, 7:32 pm   #229
retromit
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Default Re: Commodore PET 2001 voltage regulators

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Or stupid, possibly. Time will tell.

On a brief read through the respective data sheets both use VPP of +25V and both use a 'standard' programming pulse (low on pin 20 for 50mS) so it looks quite hopeful.
It will be interesting to see how you get on with these. When you mentioned the TMS2532 last night I did find these on eBay and was tempted to try them with the first socket I built, but was then a bit unsure (although the programmer I have can apparently handle 2732s).

If they work, then it could be a good solution going forward.
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Old Yesterday, 9:29 pm   #230
SiriusHardware
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Default Re: Commodore PET 2001 voltage regulators

It's up to you of course but the Hitachi devices are due to arrive at the start of next week, so maybe wait until I've had a chance to try programming one as they are quite a bit cheaper than TMS2532s.

Buying ICs of any sort online can be a bit of a minefield, the more desirable or rare a part is the greater the possibility that it has been faked, often by rebranding / rebadging a relatively common device as the rarer one. You really don't know what you're going to get these days.

I'll let you know how these ones work out.
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Old Yesterday, 10:36 pm   #231
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Default Re: Commodore PET 2001 voltage regulators

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Originally Posted by SiriusHardware View Post
Or stupid, possibly. Time will tell.

On a brief read through the respective data sheets both use VPP of +25V and both use a 'standard' programming pulse (low on pin 20 for 50mS) so it looks quite hopeful.
Unusually I resisted the urge to add to my collection of PROMS and EPROMS... well done Sirius.
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Old Yesterday, 11:23 pm   #232
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Default Re: Commodore PET 2001 voltage regulators

On more careful inspection I notice that my All07A Eprom programmer has a fixed algorithm for TMS2732 which applies 25V VPP but also 6V VCC during programming. The Hitachi datasheets don't make any suggestion of doing this on their chips, or not that I have found so far, so it might be unsafe to try to directly program the HN462532s as though they are TMS2532s.

If I look up how the programmer programs more conventional 2732s it uses +25V VPP but only 5V VCC, so it might be safer to make an adaptor to twist the TMS2532 / HN462532 pinout into the footprint of a 2732 and select 2732 (generic) in the programmer's menu to make sure it only uses the basic 50mS programming pulse, and not some manufacturer specific fast algorithm.

I'll probably try it both ways - the second way, if that works, would be more widely useful for the rest of you who probably can program 2732 / 2732A but not 2532 / 2532A due to its less common pinout.

I hear a lot of noise about the limitations of those popular TL886 programmers, mostly that they can't generate enough output voltage to properly support 25V VPP devices like the 2716, 2732, although they may be able to program the '...A' versions which are usually 21V.
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