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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 11th Jul 2018, 4:49 pm   #21
SiriusHardware
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Default Re: Tesla MH74S571 programming.

Quote:
Originally Posted by georgedb View Post
That is an interesting remark, about all connections defaulting to 0 rather than 1... That would suggest a completely different setup/technology was used.
That's actually completely normal for Bipolar PROMs, in which the programmable element is literally a fine fuse which has to be blown open circuit to represent one state, or left intact to represent the other.

In EPROMs an electrical charge is pushed onto the gate of a FET where it will stay for several decades before finally fading away. Despite this, EPROM programmers are often still referred to as 'Blowers' even though they don't really blow anything.

I mentioned the default logic state in the Tesla devices only because the German data sheet (discussed earlier) appeared to be describing a device in which the default state of all the bits was 'H', or 1. That makes it unlikely that the data sheet describes the Tesla device.
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Old 11th Jul 2018, 5:38 pm   #22
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Default Re: Tesla MH74S571 programming.

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Originally Posted by SiriusHardware View Post
My objection was to Tesla giving their device almost the same device number as the original National Semiconductor device thereby strongly suggesting (intentionally or otherwise) that their device is a direct electrical / electronic substitute for the DM (Nat Semi) device, but then not adopting the same programming regime.
I think there was a Texas Instruments PROM with the number SN74S571. It would be compatible in read mode, but not for programming. I don't think Tesla have done anything 'wrong' here.

The manufacturer (and thus the prefix letters) ARE important when you are programming the device. Once programmed, the Nat Semi, Texas and Tesla chips all read the same way and could be used in the same application circuit.
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Old 11th Jul 2018, 5:46 pm   #23
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Default Re: Tesla MH74S571 programming.

Yes, I concede this has parallels in the world of EPROMs where every manufacturer's version of (let's say, 2764) would offer its own fast-programming algorithm, for which the specific device AND manufacturer had to be selected in order for it to work.

The difference was that with EPROMs there was always a fall-back 'slow' algorithm which would work with any 2764, usually accessed by choosing 'Manufacturer: Generic'.

No such luck with these bipolar PROMs, unfortunately.
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Old 11th Jul 2018, 5:52 pm   #24
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Default Re: Tesla MH74S571 programming.

To go slightly off-topic, it can be worse with EPROMs. A TMS2716 (Texas) is a totally different device from everybody else's 2716 and is not even compatible in read mode. [The TMS2716 is a 3-rail part needing +5V, +12V and -5V, all others (as far as I know) needed +5V only].

And even on later EPROMs the programming voltage wasn't always the same. Some 27128s needed 21V, others 12.5V. If you were lucky the latter had 'Vpp=12.5V' as part of the numbering on the package. But not always.
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Old 11th Jul 2018, 6:01 pm   #25
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Default Re: Tesla MH74S571 programming.

Yes, true.

Thanks for the warning about the TMS... devices which I have thankfully never encountered.
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Old 12th Jul 2018, 5:06 am   #26
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Default Re: Tesla MH74S571 programming.

If anyone needs 2716's I bought 50 of them a decade ago and have only used 8. They're AMD devices I recall that have a single supply rail. I'm sure I could be pursuaded to part with some!

Getting back to Tesla proms, I have a few blank ones so when I get my MK14 working I'll have a go at experimenting to see if the data sheet I translated is accurate/correct etc.
Spare time is still a bit rare at the mo but hopefully that will change soon!
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Old 12th Jul 2018, 10:15 pm   #27
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Default Re: Tesla MH74S571 programming.

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Originally Posted by georgedb View Post
Thanks for the binaries. I own an issue V and they are still called IC2 and IC3

See the pictures.
Thanks for the images. One thing I notice is that your PROMs (if that is your actual machine in the photos) have blue and green 'dots' attached.

This was Science Of Cambridge's original way of marking programmed 'New OS' PROMs supplied as an upgrade, and probably also those which were supplied as standard with later issues of the machine than mine. With both device numbers being the same but each one having to go in a specific socket, they had to be told apart in some way. The coloured dots were the method chosen. The PROMs in your picture already have their 'dots', so that suggests they are already programmed?

If that is your machine (and it is already working) would you do us a small favour, look at address locations 0000, 0200, 0400 and 0600 and see if they all contain the same data, namely the first byte of the OS?

There was an official 'mod' propagated by Science Of Cambridge which removed the unwanted OS images from the address range 0200-07FF which then made it possible to map an additional 1.5K of offboard RAM into the address range vacated by the unwanted images of the PROM. (See slothie's other recent thread about the MK14 for more about that).

There is a theory that the issue V PCB incorporated this mod.

If it does, you should only see the first bytes of the OS at 0000-onwards, with some other value in memory at 0200-onwards, 0400-onwards and 0600-onwards. I would be interested to know if that is the case.
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Old 13th Jul 2018, 7:04 am   #28
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Default Re: Tesla MH74S571 programming.

I would love to check for you, but the keyboard needs to be rebuild from scratch which will take a lot of time, and currently the machine keep on resetting (which shouldn't be a big issue to trace, but this also requires time). In parallel I'm planning to build a new one based on Martin's PCB (but I haven't collected all parts).

When the issue V is up and running, I will do these checks.
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Old 13th Jul 2018, 12:30 pm   #29
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Default Re: Tesla MH74S571 programming.

Ah, so that's an original issue V MK14 you have there - just noticed that the PROMs are DM (National Semiconductor) parts as supplied by SOC. Have you owned that one for all of its life?

I guess you need the Tesla PROMs for the still to be built Czech replica.
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Old 13th Jul 2018, 1:49 pm   #30
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Default Re: Tesla MH74S571 programming.

Got a reply from Tesla... These are the pages we all know: page 430 - 433 and from some other source as it seems page 140 en 151

----
Hello,
It is so big history. I can only advise some webpages. It is all.

Datasheet scan in Czech (datasheet plus process of programming):

http://www.teslakatalog.cz/MH74S571.html

Programmers for this device

https://www.elnec.com/en/device/Tesla/MH74S571/

Good luck!

TESLA
----

I will actually forget about the 21V and take this material as the truth. Started translating things a bit the other day, the English translation that I have seen is a bit wobbly, but typing this in takes ages and I'm no expert in this field. What would be handy is an OCR-ed version of the text, which I could feed to Google Translate. There might be some online OCR tool, will check in the weekend.
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Old 13th Jul 2018, 1:51 pm   #31
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Default Re: Tesla MH74S571 programming.

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Originally Posted by SiriusHardware View Post
Ah, so that's an original issue V MK14 you have there - just noticed that the PROMs are DM (National Semiconductor) parts as supplied by SOC. Have you owned that one for all of its life?
No, I bought it for EUR 55,= 2 years ago (and still am searching for a good solution for the keyboard (and the goal is to keep it as original as possible).

Quote:
I guess you need the Tesla PROMs for the still to be built Czech replica.
Exactly.
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Old 13th Jul 2018, 6:10 pm   #32
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Default Re: Tesla MH74S571 programming.

Page 143 is the page I did the ghetto translation of for the 1st post in this thread. It is a bit wobbly but I only spent a couple of hours with online OCR and google translate.until I got something I thought was barely comprehensible
It's nice that Tesla seem to have confirmed its the right datasheet though.
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Old 13th Jul 2018, 6:31 pm   #33
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Default Re: Tesla MH74S571 programming.

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Originally Posted by georgedb View Post
No, I bought it for EUR 55,= 2 years ago (and still am searching for a good solution for the keyboard (and the goal is to keep it as original as possible).
You... lucky.... ~@~!!

Do you realise how much original MK14s can go for nowadays? Even two years ago it was not unusual for examples which were physically poor / not even working to go for upwards of 400-500. Better examples with a working, original keypad, a nice manual and one or two of the optional boards were sometimes fetching about 900 or more.

I think the emergence of all these replicas recently will actually devalue the original machines somewhat because before, people had no choice, if they wanted one they had to buy one of the original machines which tended to come up relatively infrequently. Now, they can have the experience of owning a machine in pristine new-build condition for less money, if they don't have their heart set on owning an original machine.

As regards the keypad, I would have thought that just buying one of Martin's keypad overlays and some suitable calculator-type switch domes would get you quite close to one of the original versions of the MK14 keypad which went through several incarnations, but be careful what you wish for: I don't think any of the several keypad designs which SOC went through were considered satisfactory by their owners. The early 'Rubber Mat' version fitted to my issue II was especially dreadful.

Later issues of the MK14 (including issue V of course) provide for an alternative, the fitting of actual switches of a similar type to the one used for the reset switch or anything else which would fit in the holes.

Anyone know how to get a Czech on-screen keyboard on their Windows computer?

Last edited by SiriusHardware; 13th Jul 2018 at 6:37 pm.
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Old 13th Jul 2018, 6:48 pm   #34
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Default Re: Tesla MH74S571 programming.

Hmm, I'm inclined to agree with George when he says we should stick to a programmming voltage of 10.5V. This may explain why your PROMs had such a stressful time, Slothie.

However, that's the same programming voltage as the good old Nat Semi DM74S571. If it's not the programming voltage which is different, what is?

Programming pulse length?
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Old 13th Jul 2018, 8:55 pm   #35
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Default Re: Tesla MH74S571 programming.

Pretty much everything is different...
On the DM74S571 the programming voltage is applied to Vcc and the bit being programmed. On the MH74S571 the programming voltage is applied to Vcc and the bit being programmed is brought to 0v, the others being tied to +5v.

The programming pulses are much longer on the MH74S571, (1-20mS as compared to ~1uS) and the algorithm for repeating pulses until programming is achieved is very different. The DM74S571 specifies repeating the programming pulse 5 times after success, whereas the MH74S571 says to stop when success has been achieved, with different pulse widths on each attempt.
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Old 13th Jul 2018, 9:19 pm   #36
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Default Re: Tesla MH74S571 programming.

Well, those differences certainly explain why programming them as DM74S571s will not work at all.

It sounds as though you have the makings of a first attempt at programming when you finally get the chance to do so, although I know you are busy right now. In the meantime we should hopefully get independent confirmation of your detailed algorithm, possibly several days from now.

As the other source almost certainly got their data from this same datasheet I think it only remains to be seen whether any tuning or optimisation had to be (or should be) applied for best results.
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Old 16th Jul 2018, 10:55 am   #37
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Default Re: Tesla MH74S571 programming.

Quote:
Originally Posted by SiriusHardware View Post
Quote:
Originally Posted by georgedb View Post
No, I bought it for EUR 55,= 2 years ago (and still am searching for a good solution for the keyboard (and the goal is to keep it as original as possible).
You... lucky.... ~@~!!
This word starts with a "B", right ;-) Yes, I was, and am still, very happy with it... I know technically the keyboard works fine, but it is a lot of work to fix it. I got new membrane domes (different from the ones Martin is using), I got the original cover (the sheet with the captions) and front plate (black metal) and all transparent plastic parts. And I got new material to surround the domes that needs to be glued on the PCB (not glue, self adhesive foil).

I don't know if it is something unique, but I had never seen a picture of it before: I got a MK14 power supply (see picture).

Quote:
Do you realise how much original MK14s can go for nowadays? Even two years ago it was not unusual for examples which were physically poor / not even working to go for upwards of 400-500. Better examples with a working, original keypad, a nice manual and one or two of the optional boards were sometimes fetching about 900 or more.
Insane, but true indeed.

Quote:
I think the emergence of all these replicas recently will actually devalue the original machines somewhat because before, people had no choice, if they wanted one they had to buy one of the original machines which tended to come up relatively infrequently. Now, they can have the experience of owning a machine in pristine new-build condition for less money, if they don't have their heart set on owning an original machine.
Not sure about this, but we will see. Luckily I didn't pay a fortune...

Quote:
As regards the keypad, I would have thought that just buying one of Martin's keypad overlays and some suitable calculator-type switch domes would get you quite close to one of the original versions of the MK14 keypad which went through several incarnations, but be careful what you wish for: I don't think any of the several keypad designs which SOC went through were considered satisfactory by their owners. The early 'Rubber Mat' version fitted to my issue II was especially dreadful.
I think Martin needed to adapt something to get it working and I'm trying to keep things as original as possible. More original than what I'm planning to do is, as far as I can see, impossible....

Quote:
Later issues of the MK14 (including issue V of course) provide for an alternative, the fitting of actual switches of a similar type to the one used for the reset switch or anything else which would fit in the holes.
From a functional perspective, that is actually the only solution that gives the user a keyboard that you can work with. Those buttons can still be bought in many places (but without any caption). I'm actually not sure if SoC ever sort of provided a set of keys with captions that you could buy?

Quote:
Anyone know how to get a Czech on-screen keyboard on their Windows computer?
There seems to be a lot of info through Google. didn't take the time to check the details, but it might be that you need to add a keyboard layout through your language settings first and I guess that once you activated a keyboard, you can't separate between the on-screen keyboard and the normal keyboard. Not sure, you would need to check.

I guess the background of your question is that you want to try to Google Translate the datasheet? I online OCR-ed the datasheet to Word (then you still got the layout) and started translating sentences, that you can now easily select. But, as it is Word, things started moving on the page and it all became crap. It took me a lot of time only to find out that my whole page was based on font size 4! When I tried to change it to a normal font size, Word distorted the whole page, I suffered from severe Technology Related Anger and threw it away, thinking to set it up from scratch, with a layout as close as needed to the original datasheet. That's were I still am ;-)
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Old 16th Jul 2018, 10:55 am   #38
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Default Re: Tesla MH74S571 programming.

Moderation is gone for this thread?!
;-)
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Old 16th Jul 2018, 12:23 pm   #39
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Default Re: Tesla MH74S571 programming.

Quote:
Anyone know how to get a Czech on-screen keyboard on their Windows computer?
I'm using language = Dutch and normally using the keyboard layout "US International" (for the diacritics used in Dutch). Just added "Czech (QWERTY)" as a keyboard layout within Dutch. I can now switch keyboard layouts on the task bar. So, I did not add a new language... When I switch to "Czech (QWERTY)", both the normal (physical) keyboard and the on-screen keyboard use that layout, you can't separate between keyboards. But I think that works well for the purpose? But actually, using Google Translate and not using any Czech diacritics, makes Google suggest the right words. OCR-ing and not checking carefully can lead to slightly different words, with a totally different meaning ;-)
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Old 16th Jul 2018, 11:12 pm   #40
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Default Re: Tesla MH74S571 programming.

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Originally Posted by georgedb View Post
Moderation is gone for this thread?!
Not for the thread. For you.

The first few posts by new members are moderated before they are released into the wild. I understand why it's done but it can be very confusing for everyone, because you may make a statement or ask a question in a post: At that point the post is held and time stamped, and others may post questions in the thread after you, unaware that you have already said something relevant or answered the question they have just asked - then your post gets the go-ahead and is inserted into the thread in chronological sequence where it may not even be noticed behind the several other posts which have been posted since. So it's good that you are through that at last, and can post in real time.

OK, we have a good idea of what you are trying to achieve with the keypad now. It seems you like to set your bar very high, so good luck.

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.

An original SOC supplied MK14 PSU must be one of the rarest of all original MK14 items because the majority of MK14 owners never bought one, they just used something they had. I shudder to imagine what some completionists might be prepared to pay for that, no matter how utterly ordinary it is, especially if it is actually branded or marked in some way.

Regarding keyboards: I wanted to be able to pull up a mobile-style on screen Czech keypad specifically for the purpose of transcribing the data sheet manually into English without altering the setup for my main keypad, yes. Obviously OCR is an approach that can work, Slothie used it for his attempt, which I thought was not bad.

Edit: We have gone some way off the original narrow topic of PROM programming here, so may I suggest we continue the wider discussion in Slothie's other more general thread about the MK14.

I will try to pursue the third party information about PROM programming in the next few days as promised, and will report anything I can here in this relevant thread.

Last edited by SiriusHardware; 16th Jul 2018 at 11:17 pm.
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