Did the SC/MP find its way into any home computer or game console?

[Karen O]

The SC/MP microprocessor has a special place in my heart. It was (is) very under-powered compared to other micros of its day (0.08MIPs as compared to 0.5MIPs typical) but you could still accomplish a lot with it.

I've found reference to only one major application of this micro - controlling lifts somewhere in the USA - bit I wonder if it ever found its way into any mass produced home computer or game console? I suspect not.

Was there ever a disk operating system for the SC/MP?

I'm rather hoping someone can fill in gaps in my knowledge, but seeing as National did target this micro at industrial applications (those for which a microcontroller might be used today) I doubt there are significant gaps.

[TonyDuell]

I assume you don't count the obvious MK14 as a home computer.

It was also used in the Softy 1 EPROM programmer (somewhat similar to the MK14), which although advertised in hobbyist magazines is not really a home computer.

I've seen the SC/MP as the controller in computer digital cassette drive. And in at least one cash register. But of course both are embedded aplications running non-user-changeable firmware.

I thought there was a computer games unit that had an SC/MP in it. Possibly a chess game. But I can't find any references to it, so I am probably mis-remembering.

What was the processor in the Philips 6400-MC kit? The manual, alas, doesn't include a circuit diagram. It is similar to the SC/MP in some ways (there's the same status register, with 3 flags and 2 sense inputs on external pins) but with a different (and much nicer) instruction set.

[Karen O]

Actually, I vaguely remember a chess computer project in one of the hobby mags. I rather think that used an SC/MP.

[SiriusHardware]

My spare SC/MP and INS8154 RAM/IO ICs came from a scrapped commercially made EPROM programmer with a large keypad and a blue flourescent display. Sadly, I don't remember the make or model.

I salvaged the keypad keyswitches and the toroidal 8V + 30V power supply transformer as well, and the low-voltage side of the latter is what now runs my MK14.

A friend built the Elektor SC/MP system which was roughly contemporary with the MK14 and, thanks to Sinclair's notorious methodology of offering goods, taking payment for them and not actually supplying them until several months later, that system ended up being the first microprocessor system of any sort that I ever programmed - but gosh, it was primitive. Switches and LEDs for binary address and data input and output, and individual LEDs to indicate the same.

By comparison the MK14 (With keypad input and 7-segment displays) was rather luxurious, at least until I started to try to use the keypad.

[Andrew Mawson]

My SC/MP ended up doing simple control on my home central heating - it was then replaced by an 8085 development board, and subsequently a Win98 PC doing the same function where I added logging of electricity, water and gas consumption and five zone control (It was a big house). Confused the heck out of the buyer when we sold

[Karen O]

My first programming experience was with the Mk14. I wonder how many engineers were trained by Sir Clive? The 'proper' 8 bit machines didn't interest me (and I'm not a games person). Perhaps that was the first sign that I was destined to be an embedded developer.

There was another 'trainer kit' sold by Bywood Electronics (?) - the Scrumpi. I remember the adverts featured cartoons of country bumpkin types extolling the virtues of scrumpi. I read recently that the owner of that enterprise died obscenely young.

[SiriusHardware]

I believe the MK14 was itself derived from the SC/MP based 'National Introkit', which is what I think we see in this video here:

https://www.youtube.com/watch?v=fK-IZuIonnY

It's worth a watch.

The monitor / user interface / OS from the Introkit is, as far as I know, identical to the original OS of the slightly later MK14. The Introkit has the same Go / Mem / Abort / Term command keys.

[Timbucus]

Paul Robson points out in his reply to your post on that video - which is great by the way thanks for linking it - that the MK14 is an exact copy. The story behind it is here as well if you haven't seen this excellent article:

https://www.theregister.co.uk/2014/0...an_williamson/

[mole42uk]

There’s an interesting comment in that piece: “ But in the mid-1970s no one in the UK was willing to take a chance on the computerised slot-machines that were changing the way teenagers got their kicks.”
I was working in 1977 in a company that made slot machines, our team were using SC/MP and an earlier 4-bit processor to develop control circuits to replace the relays and cam timers. I’m pretty sure that we had a production model out by 1978.
I bought and was disappointed by the MK14 which I didn’t use much. It was replaced with a NASCOM in 1980 or 81.

[SiriusHardware]

I think even the MK14's fondest fans would not claim it was a magnificent machine.

But for a period of about two years, for hobbyists with not much income, it was the difference between owning a programmable device or not owning one at all.

The Nascom and similar, more sophisticated contemporary systems were never within my reach.

[Timbucus]

I was is a similar boat with no cash - I remember first thinking about looking into MPU's when the adverts for the SCRUMPI appeared - it was nearly within my reach but, I was still quite young with no real income.

By the time the MK14 arrived which I would have been able to afford - and I remember nearly ordering one, I was busy on some other projects in electronics which needed components (A full stereo built from those Power Amp modules, with cassette desk and turntable) and doing my radio ham exam.

When I looked to MPU's again the ZX80 was advertised so I started saving for one of those as it seemed to be a real computer like all the lovely Nascom's and PET's I couldn't ever dream of owning.

In the end I got a ZX81 kit when it first came out as by then I had got into the programming side through a pair of generous teachers who had a ZX80 and TRS80 - they let me take the manuals and even the TRS80 home for a while - and of course use of the School RML380Z / Teletype to County mainframe kept me distracted until the ZX81 came out.

So I am playing with the MK14 now as what might have been...

[Slothie]

The "SCRUMPI" was made by Bywood electronics which was oned/run by John Miller-Kirkpatric, who died at the age of 32 as Karen pointed out. There's a really good article about him on The Register: https://www.theregister.co.uk/2013/1...r_kirkpatrick/

I too was someone who wanted a SCRUMPI when it came out, if only because of the funny adverts! We didn't get any of those sort of home computers because my dad ended up buying a Commodore PET for the family because he needed something that ran BASIC for work, but I pretty instantly commandeered and installed in my bedroom! Well, you know I could help him with the programming and wouldn't annoy people watching TV if we had it in the living room. Made sense to me!

I think a lot of SC/MPs must have been sold for industrial control applications, because most of the chips I've got from China are obvious equipment pulls that have been tidied up, so someone is recycling a lot of something!

[Timbucus]

I think a recreated SCRUMPI 2 and or 3 is needed after this project as I do not have any front panel switch controlled machines (yet) so the idea appeals to me. I think it should be done as well as there seems to be little or no information on them on the Internet - even the Computing Museums seem blank... Does anyone have one we can preserve?

[TonyDuell]

Originally Posted by Slothie

I think a lot of SC/MPs must have been sold for industrial control applications, because most of the chips I've got from China are obvious equipment pulls that have been tidied up, so someone is recycling a lot of something!

Quite possibly. I've got a digital cassette drive (for data storage, nothing to do with digital audio) that has an SC/MP to control it. And I am pretty sure I've seen a cash register with an SC/MP inside.

[Slothie]

Originally Posted by Timbucus

I think a recreated SCRUMPI 2 and or 3 is needed after this project as I do not have any front panel switch controlled machines (yet) so the idea appeals to me. I think it should be done as well as there seems to be little or no information on them on the Internet - even the Computing Museums seem blank... Does anyone have one we can preserve?

I looked into this and came up with the same blank. I think they only sold in their hundreds and according to the Register artical (which seems to be the best documentation available online!) “Bywood consider that ‘the PCB is its own circuit diagram’ and that further documentation is therefore unnecessary.” which probably why there is little online documentation nowadays. The aforementioned article does show a detailed manual for the SCRUMPI3 but sales of this machine were hampered by the "memory famine" of the late 70's meaning UK manufacturers were finding it hard to source parts for their computers.

I presume somebody somewhere has copies of the SCRUMPI3 manuals, because The Register managed to get photo's of them!

[Timbucus]

Originally Posted by Slothie

I looked into this and came up with the same blank. I think they only sold in their hundreds ...

I presume somebody somewhere has copies of the SCRUMPI3 manuals, because The Register managed to get photo's of them!

On that note I have written to the article's author to see if he can provide any pointers or introductions to get clear perhaps photos of a PCB etc. If he is still on the register - his linked Twitter account is either empty or re allocated.

Don't ask, Don't get...

[Timbucus]

The SCRUMPI Version 1 board was much more limited in what you could do and used the SC/MP so needed +5 / -7 to run... anyway the review on Page 577 (sheet 35) of the August 1977 Practical Electronics probably gives enough to build one...

https://www.americanradiohistory.com...cs-1977-08.pdf

Their advert on Page 606 (sheet 64) gives some more technical detail on the use of 74C173 four bit latches etc.

For the chips to use I suspect they would be from the limited range BYWOOD were advertising... see page 2 of October 1977 ETI

https://www.americanradiohistory.com...ay-1977-10.pdf

There is a good quality photo of the board here:

http://www.sunmoonstars.ca/electroni...computer-1986/

It does seem though that SC/MP chips are not immediately locatable. So I think a v2 board if a good photo and scan can be found may be better - and more usable - the bumpkin adverts are better as well!

Once we have tried the switches once we should be able to adapt Sirius Hardware's PI programmer to run code...

[SiriusHardware]

As mentioned earlier in the thread my first experience with programming any sort of microprocessor was with Elektor's very crude SC/MP system project which used rainbow coloured DIP switches to set up the address and data in binary for each byte of code, then required the user to push a momentary push switch to latch the current data data into the current address.

To hack the Pi programmer for that or any similar switch-input system you would probably have to go back to my original V1 scheme of one optocoupler (or relay, or other driver of your choice) per bit/switch, although I dare say you would not need the full 16 address bits. I would imagine, though I can not remember, that it also had a momentary 'run' switch to set the code running from the currently selected address so that, and the reset switch, would also have to be 'shadowed' as well. I think a 40-pin Pi could still do it although you might have to disable a few more GPIO pin 'alternative' functions to win back more general purpose I/O pins.

To enable the programmer to function you would also have to move all of the address and data switches to their open positions before commencing so that the programmer could either 'close' them or leave them open, as required.

One of the drawbacks of the Pi is that it does not have easily readable / writable byte-wide GPIO ports, which means that writing a byte to 8 GPIO pins usually means having to test the 8 bits of the value to be written individually and then setting each corresponding GPIO pin to the same state.

It is perfectly doable, but nothing like as quick or as simple as writing a byte value to an 8-bit parallel port.

[SiriusHardware]

I've just been having a go to 'out-Tim' Tim by trying to unearth as many SC/MP related articles as possible in Elektor UK, as usual at the invaluable

https://www.americanradiohistory.com/index.htm

Start with 'E' then work your way down to 'Elektor UK' to bring up a list of Elektor issues.

The following issues contain one or more articles concerning the SC/MP, as noted.

Elektor Nov '77 P 11-02, 'Experimenting with the SC/MP' pt1 - Simple SC/MP system with binary switch input, binary LED output

Elektor Dec '77 P 12-04, 'Experimenting with the SC/MP' pt2 - Continuing the Elektor SC/MP system project

Elektor Jan '78 P 1-24, 'Experimenting with the SC/MP' pt3 - RAM and ROM memory expansion for the SC/MP system

Elektor Feb '78 P 2-28, 'Experimenting with the SC/MP' pt4 - Hex keypad and display for the SC/MP system

Elektor Mar '78 P 3-03, 'Experimenting with the SC/MP' pt5 - Discussion of the 'Elbug' OS for the SC/MP system
Elektor Mar '78 P 3-08, Power supply for SC/MP system

Elektor Jun '78 P 6-24 Elektor SC/MP system as digital clock

Elektor Jul/Aug '78, 'Summer Circuits' project #12 software 'Kojak Siren' for SC/MP

Elektor Nov '78 P 11-35 - 'Mastermind' for Elektor SC/MP system

Elektor Dec '78 P 12-08 - 'Music Box', SC/MP playing Silent Night

Elektor Feb '79 P 2-32 'Using Elbug' - More discussion of the 'Elbug' OS of the SC/MP system
Elektor Feb '79 P 2-10 'D-A for micros', with example SC/MP code

Elektor May '79 P5-25 'Interface for uPs' - Serial interface with example code for use with SC/MP system.
Elektor May '79 P5-34 'Basic Microcomputer' - Bringing BASIC to the SC/MP system
Elektor May '79 P5-43 'NIBL-E', article about NIBL BASIC to complement the above article.

Elektor Oct '79 P10-12 'New Programs for the SC/MP - discussion of new SC/MP software available from 'Elektor Software Service'

Elektor Jan '80 P 1-31 'New Bus Board For Microprocessors' - Motherboard to plug SC/MP system PCBs into

Elektor Mar '80 P 3-28 'Printer for Microprocessors' - Printer interface for SC/MP system, includes code listing of a disassembler

Elektor May '80 P 5-04 'Elektor Microprocessors' - Round-up of recent Elektor uP based projects
Elektor May '80 P 5-08 'Junior Computer' - Not SC/MP, but a 6502 based Hex input / Hex display microcomputer project

Not sure if I missed anything, but if I did, no doubt Tim will find it.

All of the hardware articles include Elektor's beautiful PCB artwork - the 'Junior Computer' article is complete with the monitor code listing so you have everything you need to make a 6502 system with hex entry / readout in that one article.

[Slothie]

Originally Posted by SiriusHardware

All of the hardware articles include Elektor's beautiful PCB artwork .

I always loved the PCB designs Elektor had. They were, as you say, beautiful.
Unfortunately at the tme it was hard for me to find a reliable supply of Elektor and as a penniless schoolboy a subscription was out of the question!