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Old 18th Jan 2023, 9:54 pm   #1
Timbucus
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Default Advanced Mk14 Enhancements

Yes I agree a new thread - the keyboard (4x10 matrix) was promised by Sinclair with BASIC but never delivered:

http://www.computinghistory.org.uk/d...Update-Letter/

There is a classified in Computing Today somewhere (Dec 1980 maybe) for an ad for an improved monitor with Alphanumeric Keyboard, labelled files and VDU routines Mr P.R. Trevellick, Oxford.
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Old 19th Jan 2023, 6:44 am   #2
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Default Re: Advanced Mk14 Enhancements

Moved from the mk14 pico uploader thread

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Old 19th Jan 2023, 8:29 am   #3
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Default Re: Advanced Mk14 Enhancements

The keyboard was the last of quite a long list of future options in order of appearance. I would of expected the priority to be keyboard first, then NIBL, before the other options listed.

Does anyone have any info on the monitor to link the MK14 to a teletype? Was it just the original LCDS monitor before the keyboard and seven segment display option?
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Old 19th Jan 2023, 9:00 am   #4
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Default Re: Advanced Mk14 Enhancements

Quote:
Moved from the mk14 pico uploader thread
Thanks, David.
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Old 19th Jan 2023, 9:05 am   #5
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Default Re: Advanced Mk14 Enhancements

Quote:
Was it just the original LCDS monitor before the keyboard and seven segment display option?
The OS for the original, basic teletype-driven National Introkit (without keypad and display) was called KITBUG, I believe. When the keypad and display were added then the OS was replaced with SCMPKB, which is the same as the original version of MK14 OS.
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Old 19th Jan 2023, 9:08 am   #6
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Default Re: Advanced Mk14 Enhancements

Quote:
Originally Posted by Timbucus
an ad for an improved monitor with Alphanumeric Keyboard, labelled files and VDU routines Mr P.R. Trevellick, Oxford.
Incredible. I knew that if anyone would have come across anything like that, it would be you. What a shame no such enhanced example has survived... as far as we know? The problem was that the ZX80 had been launched in Jan 1980, and even allowing for Sinclair's usual delay-to-market was probably available by December, so that would have been the footstep of doom to MK14 innovations like this and the interesting 'Z80 conversion' which you flagged up elsewhere.

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Old 20th Jan 2023, 9:08 am   #7
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Default Re: Advanced Mk14 Enhancements

Quote:
Originally Posted by Timbucus View Post
Yes
>> the keyboard (4x10 matrix) was promised by Sinclair with BASIC but never delivered:

http://www.computinghistory.org.uk/d...Update-Letter/

There is a classified in Computing Today somewhere (Dec 1980 maybe) for an ad for an improved monitor with Alphanumeric Keyboard, labelled files and VDU routines Mr P.R. Trevellick, Oxford.

Thanks for the pointers to these. I found a copy of that letter as a pdf (attached, for ref)


And looking in the text of Dec'80 Computing Today, at: https://archive.org/details/computing-today-1980-12/ Finds:

"MK14 PLUS VDU OWNERS: New monitor available. Runs VDU, encodes alphanumeric keyboard, includes cassette Operating system. Uses existing hardware. SAE to: P. R. Trevellick, Queens College, Oxford."

Looking through the (also OCR'd) PDF, I also spotted a few other interesting things:

- A program-listing for a reaction tester for the MK14 on page 13.

- A ZX80 Xtra feature - So seems Sinclair had managed to delivery some in 1980! (The Index in this issue shows it was reviewed in Jun'80 issue)
And elsewhere, Comp Computer Components were already selling 'Refurbished' ZX80 and offering to part exchange your 'old' ZX80 !

- A Zetron Chess Computer ad (I wonder what processor that one used)

- An SGS-ATES Nanocomputer teaching aid, using (their second-source) Z80 with it expandable to have full Qwerty keyboard and VDU board etc.

- I do recall the 'Breadboard' (80) electronics exhibitions advertised in there (but didn't realise they lasted 5 days)

- GP Industrial Electronics full-page ad for the (E)P4000, that used the SC/MP, as well as the Softy and a rather rare printer for it (costing more than a built Softy), using Electrosensitive-paper, so presumably similar to later ZX Printer?

Another classified ad was listing replacement display PCB kits + a "keyboard"(Presumably just the original "Keypad"):
"MK14 CORNER. Interface board, includes flag driven mains relays, LED indicators for all Serial |/C, D/A and single step chips, and prototype area; also suitable for other Microcomputers; PCB and circuit £3.95. Replace calculator display with 1/2" FND 500's; PCB, filter, instructions £1.95. Ready built replacement keyboard £11. Useful notes on MK14 75p. Rayner, ‘Kismet’ High Street, Colnbrook, Bucks."

Interestingly, I note that even back then the SC/MP-II INS8060 despite often being referred to as as lower/reduced cost CPU, was actually one of the more-expensive ones, with the Z80 and even 4MHz Z80A being a bit cheaper. Plus the 6502 was even less. And the 8080 cheaper still, so it seems the release of the Z80 had driven its price down substantially.

And nobody seems to be listing 2111 RAM IC's, so must have been getting quite rare even back then.
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Old 20th Jan 2023, 11:08 am   #8
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Default Re: Advanced Mk14 Enhancements

And here's an intriguing advert in December 1980's Personal Computer World.

Perhaps they actually meant keypad. We may never know.

Colin.
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Old 20th Jan 2023, 11:34 am   #9
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Default Re: Advanced Mk14 Enhancements

Good spot - sad that he was selling it for £40 which is less than the combined MK14, cassette interface and whatever the parts for the 'keyboard' cost originally, so it shows that the system was already on the wane.

If only he'd hung on to it for 40 years, he could probably have sold it for between £600-£1000 at one point. I think the recent availability of so many replicas has brought the price of original machines down to a less silly level now. Some of the people who might once have been contenders for an original machine just wanted to relive their youth, and a replica will let you do that, usually with a much nicer keypad. It's only the serious collectors who are still chasing after original machines now.

In this context I think the 'Keyboard' in that ad was probably just a better third party or homebrew keypad or maybe a newer-version original SOC one, as the SOC keypads evolved two or three times with the final versions having clear plastic buttons pressing down on dome contacts.
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Old 20th Jan 2023, 6:47 pm   #10
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Default Re: Advanced Mk14 Enhancements

As this thread is about advanced MK14 enhancements, I'd like to find out how I built my MK14 colour graphics extension, with programmable sprites and, IIRC, collision detection.

This was back in the day, and the veroboard has long since gone. I've still got the chips, but can't remember what they do.

I think the CT430 was the sync gen, but what were the CT429 and CT455 doing ?. These are Signetics chips, but my quick Googling finds nothing about them.

If anyone can shed any light on these chips I might just have a go a building it again, or post the chips to someone who would be quicker !.
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Old 20th Jan 2023, 10:26 pm   #11
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Default Re: Advanced Mk14 Enhancements

I tried (and tried) but I can not find anything for Signetics (or Philips) under those numbers. CTxxx, that's really their full ID?
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Old 20th Jan 2023, 10:38 pm   #12
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Default Re: Advanced Mk14 Enhancements

While I was looking I did find this interesting discussion about graphics ICs with inbuilt support for graphics ICs:-

https://retrocomputing.stackexchange...rites-in-the-7

There is no mention at all of your chip set but they did mention a couple of single chips the Signetics 2636 and 2637.

In an earlier discussion about similar subjects TonyDuell also brought up the idea of using i2c controllable teletext graphics ICs.

None of which helps you, unfortunately, Buzby.
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Old 20th Jan 2023, 11:30 pm   #13
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Default Re: Advanced Mk14 Enhancements

Here are the chips in question.

They probably came from an arcade machine of some kind. I had a job in an arcade machine repair shop for a while.

Maybe I was reading the numbers wrong, one of these has 2636 written on it.

I found this page about the chipset. https://en.wikibooks.org/wiki/Signet...mming/2636_PVI

The 2650 is a CPU, I don't think I used that. The 2636 is the chip I interfaced to the MK14.
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Old 21st Jan 2023, 1:05 am   #14
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Default Re: Advanced Mk14 Enhancements

Oh, so my fruitless search did turn up something after all. That big video chip surely must be a 2636. Might be possible to dig up something about it on Bitsavers now that we have a different number to look for.
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Old 21st Jan 2023, 2:04 am   #15
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Default Re: Advanced Mk14 Enhancements

I think David is fighting a losing battle here, he just moved the head post of this thread yesterday and its already looking like two more threads worth of posts.
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Old 21st Jan 2023, 10:15 am   #16
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Default Re: Advanced Mk14 Enhancements

Quote:
Originally Posted by Buzby123 View Post
Here are the chips in question.

They probably came from an arcade machine of some kind. I had a job in an arcade machine repair shop for a while.

Maybe I was reading the numbers wrong, one of these has 2636 written on it.

I found this page about the chipset. https://en.wikibooks.org/wiki/Signet...mming/2636_PVI

The 2650 is a CPU, I don't think I used that. The 2636 is the chip I interfaced to the MK14.
The CT429IC = Signetics 2650A, uP (2MHz version)
The CT430I = Signetics 2621, universal sync generator
The CT455I = Signetics 2636I, Programmable Video Interface

I remember in the early 80's having a programmable games console that used these parts (can't remember the name of it now). It was sprite based and you could get some very good results if you put in the time to learn the PVI architecture.

Here's a link to a video arcade PCB - Sub Hunter - that uses these parts, has links to datasheets and a full circuit diagram of the board. It uses 3 x PVI, so must have been quite impressive.
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Old 21st Jan 2023, 11:26 am   #17
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Default Re: Advanced Mk14 Enhancements

The chips were also used in the Elektor TV games project, which is where I think I got the idea from. The Elektor project was way too complicated, it had all the possible bells and whistles. So I just used the USG and PVI direct to an RGB monitor.

The PVI mapped into 256 bytes of the MK14 address space. I do remember programming the picture of a train engine from Elektor, and making it move across the screen.

It would be fairly simple to build a new circuit, and with the full pinout on Slothie's board it wouldn't need all the wires I had soldered on the back of Micky.

If anybody wants to try, I've got some spare USG and PVI chips.
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Old 21st Jan 2023, 12:21 pm   #18
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Default Re: Advanced Mk14 Enhancements

Quote:
David is fighting a losing battle here....
No, that's why I made the title of this thread intentionally very broad in scope. Wander wherever you like, within the scope of this thread title of course. .

I have been trying to find the thread where we did discuss the possible layout of a 40-key keyboard for the MK14 which included a couple of hand drawn sketches by Timbucus, but with no luck so far.
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Old 21st Jan 2023, 2:42 pm   #19
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Default Re: Advanced Mk14 Enhancements

This was where we talked about the possible layout of a 40-key keyboard and how it would be used. Around post #63 onwards, with Tim's sketch a few posts further down.

https://www.vintage-radio.net/forum/...=182113&page=4

I think the general idea was that keys 0-9,A-F, G,M,T on a larger keyboard would be mapped onto the same places as they are on the standard keypad so that the extended keypad could be used to drive the original monitor in the usual way. All other keys would be dropped into the currently 'unpopulated' slots in the 10 * 4 matrix and one of those would have to double up as 'Abort' (Esc, perhaps?).

I have another idea which is to take an off the shelf ZX81 keyboard membrane, scan it with a PIC or Arduino and send its output to an opto matrix similar to that used by the various uploaders, although there would need to be 14 optos in the interface, 15 if you wanted to be able to reset the MK14 from the extended keyboard.

The ZX81 keyboard at least has an ancestral link to the MK14 and the required PCB mount connectors are available from the same places as the keyboards themselves.
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Old 26th Jan 2023, 3:21 pm   #20
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Default Re: Advanced Mk14 Enhancements

I'm looking at interfacing a UART \ ACIA to my Mk14 (6402 or 6850 most likely rather than something needing a lot of s/w setup). So not wanting to re-invent any 'wheels' I would be interested in any pointers to existing work in this area ?
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