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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 17th Jul 2018, 4:52 am   #41
TonyDuell
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Default Re: Tesla MH74S571 programming.

Quote:
Originally Posted by SiriusHardware View Post
I think SOC did offer sets of switches as an option for fitting in place of the dome contact keypad but if they did I do not believe they were already legended - the reason I say that is that I have seen a number of images of late issue MK14s with switch sets fitted, but none of them have ever been professionally legended. Of course the owners in the cases mentioned may just have chosen to source their own switches if they found they could do so more cheaply.
I never saw any adverts. etc for an official kit of switches (and coincidentally, I was tidying up some MK14-related paperwork yesterday). But the late version PCBs could take a keyboard switch that Maplin sold (I think they called it a 'clickswitch') and of course that was mentioned in magazines at the time. Many MK14 owners fitted 20 of those with white caps for the digits and some other colour caps for GO/MEM/ABORT/TERM (where did those names come from??). Obviously you then had to label them with Letraset or similar.
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Old 25th Jul 2018, 7:59 pm   #42
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Slothie, georgedb, you have PMs.
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Old 8th Aug 2018, 2:10 pm   #43
kazzawozza
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Default Re: Tesla MH74S571 programming.

Hello,

I'm tagging along here as I too have some Tesla MH74S571 chips that I want to be able to program. In my case I want to use them in an Acorn System 1 rather than an MK14.

The computer's currently got its monitor program in an EPROM, but I'd like to migrate it to the PROM chips and have the EPROM available for my own programs.

I'm not in a rush to get them programmed, but would appreciate any feedback on your experiences in programming yours.
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Old 8th Aug 2018, 6:19 pm   #44
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Kazzawozza, how would you be planning to program yours - are you just looking to get some programmed any way you can, or are you seeking sufficient info to make your own programmer based on something like an Arduino or PIC?

I believe Slothie and georgedb now have enough information between them to begin to put together a crude hobby programmer for these devices, but I don't think either of them have made a start yet (real life keeps getting in the way).

I'm interested as well from a purely technical / knowledge based point of view but unlike you three, I don't have any Tesla devices which need programming.

(Note: As a new forum member, your first few posts will be subject to moderation before they appear).
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Old 9th Aug 2018, 9:09 am   #45
georgedb
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Default Re: Tesla MH74S571 programming.

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Originally Posted by SiriusHardware View Post
I believe Slothie and georgedb now have enough information between them to begin to put together a crude hobby programmer for these devices, but I don't think either of them have made a start yet (real life keeps getting in the way).
Exactly... Might take some months rather than weeks before I can even have a look at it and even then there are a lot of things to investigate and try, it might take days before I got something working. But, we'll get there ;-)
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Old 9th Aug 2018, 9:58 am   #46
kazzawozza
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Default Re: Tesla MH74S571 programming.

Hi Sirius,

I'm fairly open to my options as to getting these programmed. Ideally I'd like to do it myself, but if someone were to knock on my door and offer me a pair of ready-programmed PROMs I wouldn't turn them down.

I don't anticipate programming any further PROMS after the pair for my System 1, so a temporary, Heath-Robinson jury-rig would do the job fine. As it happens, a (DM74S571) PROM and EPROM programmer was manufactured for the Acorn System range, and a circuit diagram exists (https://www.4corn.co.uk/archive/diag...Programmer.jpg) but I don't know of any surviving software to go with it. I've only just gotten my System 1 working, and I'm not up to writing my own programming software (in assembly) quite yet! I'd probably be more likely to try coming up with something standalone, or lash something up to either a BBC micro or an arduino instead.
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Old 9th Aug 2018, 10:29 am   #47
SiriusHardware
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Default Re: Tesla MH74S571 programming.

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Originally Posted by kazzawozza View Post
Hi Sirius,

As it happens, a (DM74S571) PROM and EPROM programmer was manufactured for the Acorn System range, and a circuit diagram exists (https://www.4corn.co.uk/archive/diag...Programmer.jpg) but I don't know of any surviving software to go with it.
Unfortunately what works for the DM74S571 does not work for the MH devices, as you will have gathered by now.

On the DM devices the bit to be programmed is programmed by raising the IC's VCC to 10.5V and then zapping the bit to be programmed with VPP (10.5V)

On the MH devices it seems the bit to be programmed has to be held at 0V and the other bits held high (5V) via 3K9 resistors. Then the IC's VCC has to be raised from 5V to 10.5V for a period of time (ie, the length of the programming pulse).

So hardware designs for DM74S571 programmers just don't apply to the MH74S571.

The other major difference between the devices is the length of the programming pulses, which on the MH74S571 are dynamically increased in length from an initial 1ms up to as long as 20ms with the bit being verified (read) after each attempt to see if it has programmed yet.
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Old 9th Aug 2018, 1:56 pm   #48
kazzawozza
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Default Re: Tesla MH74S571 programming.

Indeed. If there were some documented software to go with that circuit diagram, I'd be minded to try to adapt it to the MH74S571, but as it is one may as well start from scratch.

Thinking out how the innards work, it seems that the MH's fuses are blown between the VCC's 10.5V and the individual data pins. If they're held high at 5V, that's only 5.5V difference and within tolerance, but if they're held low then that's a 10.5V difference, enough to blow the fuse. At least that's how I've reasoned it out in my head. From what I can see the programming pulse is applied to the output gate pin.

My google-assisted translation of the programming instructions is:
  1. At first, the word is selected by adding the appropriate voltage combination to the ADDRESS A* inputs whose memory cells (bits) are programmed. The address of the word is dialed when U0 is unplugged (see definition of time series generator). The specific values of Uih and Uil for address selection are given by the recommended programming conditions.
  2. Then the output associated with the bit to be programmed will connect to Uo. The timing of this connection, as well as the disconnection with respect to the time runs on the outputs of the programming generator G, is denoted in the generators' time definitions.
  3. The remaining (not programmed) outputs are connected via the resistor R to the voltage Uz. Recommended values Uz, Uo, and R are listed in the recommended workplan for programming.
  4. The actual programming is done of the selected bit using the impulse from the programming generator G.
  5. Additionally, the correctness of programing the selected bit is usually performed. If programming is correct (burning of the programming clutch), the output of the selected (and programmed) bit in the state of level H is appropriate. This state is characterized by the Uoh parameter, the boundary of which is given in the characteristic data.
  6. If programming has not been done, the programming procedure according to previous paragraphs 3 and 4 is repeated again with a typical value of the programming pulse width X. If programming still has not been done, the programming procedure according to points 3 and 4 is repeated, but with the maximum width value pulse X.
  7. Only one bit of the selected word can be programmed at a time.

According to the timing diagram, blowing a bit is done as follows:
  • Raise VCC to 5V
  • When VCC is stable, raise S (or /G in DM parlance) to to a logic high level (2.4~5.0V)
  • No less than 10us later, start raising VCC to 10.5V. This should typically be done in 100us.
  • Within 10~1000us of VCC reaching this level, S is dropped to 0V for a programming pulse of between 1 and 20 ms.
  • When S is raised back up again, VCC should start dropping typically within 10~1000us, returning to 5V 100us later (typically).
  • S should not be dropped to 0V less than 10us after VCC has reached 5V. VCC can then also be dropped to 0V.
  • A cool-off period of 3~4 times the programming pulse is required before the next programming cycle.

Does that match other people's interpretations?

I'm unclear on what the V10 and V20 in the 'G' element of the right-hand diagram on page 143 refer to. Does anybody else have an idea?
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Old 9th Aug 2018, 2:09 pm   #49
Slothie
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Default Re: Tesla MH74S571 programming.

Thats interesting because another replica I'd really like to make is an Acorn System 1

I'm still struggling to find the time to finish my MK14, which makes me feel a little guilty given the amount of time and effort others have gone to in helping me. My proms travelled all over Europe from person to person until I got a working pair! So I fully intend to work out a programmer when I have time and publish the design to save others the pain, but at the moment I have other priorities. Also, due to having to use my "lab" as a storeroom for stuff I retrieved from Mums house before we sold it, I can't find my test equipment and can barely get to the bench!!

Still, one day things will be "back to normal" lol....
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Old 10th Aug 2018, 10:19 am   #50
GrahamN
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Default Re: Tesla MH74S571 programming.

I'm just about getting ready to build my Mk14 replica and have found a couple of 74S571 chips - can someone tell me if these are the 'easy' ones to program? They aren't marked Tesla.

If they look OK, can anyone here program them for me? My Batronix programmer won't do them and I don't really want to buy another programmer at the moment if I can get away with it!

Many thanks

Graham
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Old 10th Aug 2018, 11:57 am   #51
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Yes, Graham, those are the 'real thing', National Semiconductor DM prefix parts as originally used in the MK14 and widely supported by historic high end programmers, including mine.

If you PM me, I'll be happy to program them for you and even test them in a real MK14 before returning them. All I'd need from you would be a stamped, addressed return jiffy bag.
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Old 10th Aug 2018, 12:00 pm   #52
GrahamN
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Default Re: Tesla MH74S571 programming.

That's brilliant - thank you. Will pm you in a few minutes.
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Old 10th Aug 2018, 5:03 pm   #53
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Quote:
Originally Posted by kazzawozza View Post
I'm unclear on what the V10 and V20 in the 'G' element of the right-hand diagram on page 143 refer to. Does anybody else have an idea?
Not ignoring your question, I just don't have any idea either, hopefully someone else does.
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Old 10th Aug 2018, 10:34 pm   #54
Slothie
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Default Re: Tesla MH74S571 programming.

Quote:
Originally Posted by kazzawozza View Post
Does that match other people's interpretations?

I'm unclear on what the V10 and V20 in the 'G' element of the right-hand diagram on page 143 refer to. Does anybody else have an idea?
Yes, thats how I interpreted it.

Element G is the timing generator that creates the chip enable input (S,/G etc). This page applies to several devices some of which have 2 enable inputs... why this data sheet calls them V10 and V20 I don't know, maybe its explained elsewhere in the manual but my Czech isn't up to finding it!
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Old 26th Aug 2018, 8:36 pm   #55
Profjordan
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Default Re: Tesla MH74S571 programming.

Hi all - reading this thread with interest. I have two original MK14s. One is the earliest (Rev 0) with the membrane keyboard and a later one with the calculator click plates - I took that off and attached a bodged keyboard from an old calculator (kicking myself now - it was a Nixie tube calculator. Quite rare! Never mind). But - I have a problem with a set of 74s571 PROMs. I need (if possible) two sets blown. One with the early monitor, one with the later monitor. I have four new (old stock) dm74s571n PROMs. Would anyone be able to help? Very happy to pay, contribute to charity or whatever!

PS - my early MK14 had problems with a very dim display when I first built it at the tender age of 11 or 12 when it first came out. We ended up driving it up to 9 Kings Parade in Cambridge (thanks Dad!) where a rather tall and bearded gentleman called Clive (yes, that one) sat there with soldering iron and Fluke multimeter and sorted it out for me. Very happy memories!
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Old 27th Aug 2018, 12:44 pm   #56
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Hello and welcome PJ, brilliant story, although I think it was probably number 6 King's Parade you went to all those years ago, rather than number 9. It was remarkably kind of Clive himself to sit down and sort it, as he reportedly wasn't even very keen on the idea of a 'computer' product to begin with. It's a shame he didn't autograph it as an afterthought.

I'm curious to know how you are both fortunate enough to own not one but two original MK14s and at the same time unfortunate enough to have suffered the loss or failure of the PROMs in both machines?

As far as old OS vs. New OS goes, do you know that the 'New' OS works even in the oldest issue MK14s? It was available as an optional extra to those who, like myself, had bought early issue machines with the original OS.
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Old 27th Aug 2018, 3:46 pm   #57
Profjordan
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Default Re: Tesla MH74S571 programming.

Hi Sirius! One set works, the other (newer monitor) doesnít. The later one was a donation from a family friend. And Iím now making a third one, hence the need for two sets of monitor chips to be blown. If the new monitor works in old machines, two copies of that would be ideal. One of the originals (the later one) will be heading towards eBay once working, the newly made replica is going to a museum and Iíll be keeping my original one if I can get it working again. Hope that makes sense.

Youíre right about Kings Parade. No. 6 when I looked online. Iíve has it wrong in my head all these years! I seem to recall it was above a newsagent but I might be wrong. I also seem to recall that the display fix involved a handful of capacitors. Again, itís a long time ago...
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Old 27th Aug 2018, 11:19 pm   #58
SiriusHardware
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Default Re: Tesla MH74S571 programming.

OK, if your PROMS meet the following criteria, which your original post seems to confirm:-

-They are DM Prefixed National Semiconductors DM74S571s, not Tesla MH74S571s.
-They are unused, unprogrammed blanks - used ones can not be reprogrammed.

-Then drop me a PM and we will take it from there.
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Old 12th Sep 2018, 3:37 pm   #59
kazzawozza
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Default Re: Tesla MH74S571 programming.

Hello again,

Over on another forum I've been told that a PROM programmer configured for a Philips 82S131 can program an MH74S571. The person in question says they've programmed "lots of that [Czech] part" with a Logical Devices Chipmaster. See the forum thread here.

Looking at the programming procedure for the Philips 82S131, it is apparently programmed with VCC at 8.75V and the output bit at 17V, pulsing /CE to program. The MH74S571 expects the output bit to be grounded, and VCC at 10.5V, pulsing /CE to program. Somewhat different techniques, but I can see how the techniques could be compatible, as in both instances the non-programmed bits will be at 5V, thus within ~5V of VCC (or floating, in which case there'll be no current flowing). The significant difference appears to be the polarity of the effective voltage (and direction of current) used to blow the fuses.
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Old 13th Sep 2018, 10:33 am   #60
SiriusHardware
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Default Re: Tesla MH74S571 programming.

That's a good discovery, but, although my Hi-Lo ALL-07A can program the 82S131 I would be reluctant to risk damage to the programmer itself by using it in such unorthodox fashion, because the programmer is a real antique and spares / service information are hard to come by now. For your own needs maybe this individual with the Logical Devices programmer can be persuaded to programme them in small quantities?

I'm still pinning my hopes on someone successfully coming up with a dedicated MH74S571 programmer based on Arduino, etc. Unfortunately I don't have the incentive to do this myself because I have no Tesla devices, nor any need to buy any.

When the difficulty of programming the Tesla devices became evident I bought a couple of DM74S571 PROMs from a UK supplier to program up as spares for my MK14, since they obviously will not be available for ever. They cost me about £12 the pair, nothing like as cheap as the Tesla devices but on the other hand I had them programmed and working within minutes.
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