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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 12th Aug 2018, 4:20 pm   #81
SiriusHardware
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Default Re: MK14 schematic revisions

That sounds like a good find for the price. I think the SAB prefix (Siemens?) is a prefix not as widely known as, say, the Intel devices (P2111) so you did well to come across those.

The programmer I'll be using to program your PROMs with also has a handy IC testing feature which includes once-common static and dynamic RAM ICs, so if you'd like those tested feel free to include them with the PROMs. However, I see no reason to assume that any of them will be faulty.

Unfortunately I wouldn't be able to test those in the MK14 as they are one of the few ICs which are soldered rather than socketed in my particular machine - when I built it I happened not to have any IC sockets with the right number of pins, and I was impatient to get it built and up and running.

There must, somewhere, be large old redundant PCBs full of 2111 RAM ICs just lying around waiting to be found. I used to see a lot of that sort of thing in cardboard boxes at the larger radio rallies during the nineties.
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Old 12th Aug 2018, 4:45 pm   #82
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Default Re: MK14 schematic revisions

They are coming from Germany, so I expect a week or two - I will send them with the PROMs if I may as there is no rush on the build and it will be good to be sure they work!

From looking around the internet, the RAM seems to have been commonly used in old Atari arcade games - unfortunately arcade boards generally fetch high prices these days, so not really a viable option! (I did scour the internet looking for cheap boards or spares from the arcade spares suppliers, but no luck)

And yes - I understand these are Siemens.
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Old 12th Aug 2018, 11:23 pm   #83
Slothie
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Default Re: MK14 schematic revisions

Quote:
Originally Posted by GrahamN View Post
I tried Littlediode, but they are more expensive than the USA ones. I have, though, managed to find some (hopefully) equivalent chips (SAB2111A) from a dealer in Germany at just 4 euros each (plus shipping), so I've ordered these.
Sounds like a bargain. I wasnt able to find a datasheet for the SAB2111A but it would be surprised if its not compatible, 2111s were used in all kinds of products so it would be bzarre to make a device rhat wasnt 100% compatible, and the MK14 hardly stresses them timing wise.
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Old 14th Aug 2018, 9:06 am   #84
SiriusHardware
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Default Re: MK14 schematic revisions

Information on these is so scarce that I was worried they might not actually be RAMs at all, just some other IC which had 2111 in the part number.

However, I did find this one page referring to the use of SAB2111s as substitute 2111 RAMs for an old development system.

https://www.flickr.com/photos/51699638@N06/26956276139
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Old 14th Aug 2018, 9:30 am   #85
GrahamN
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Default Re: MK14 schematic revisions

This is the only data I could find - the actual part number of the devices I ordered is SAB2111A-D4 which is listed as static RAM 256k x 4 @ 450ns.
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Old 21st Aug 2018, 8:19 pm   #86
Pepperm
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Default Re: MK14 schematic revisions

I have a single step circuit that can switch single step on and off, I believe. It is currently on a piece of Vero board but I could reverse engineer it if any one is interested. I last used it in the 80's you see.
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Old 23rd Aug 2018, 12:07 am   #87
SiriusHardware
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Default Re: MK14 schematic revisions

No need, Pepper, that circuit is in the manual which is available from various places on the 'net'. It goes with the 'Single Step' program in the 'System' section in the original manual. The improved 'New' version of the MK14 OS has the Single Step code built in.

One word of warning, if you use the new OS and you don't add the Single Step hardware, it is necessary to tie the Sense-A input low, otherwise you'll find you can't run programs.
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Old 23rd Aug 2018, 8:27 pm   #88
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Default Re: MK14 schematic revisions

My circuit is not the same as the one in the manual and is switched. I am an original OS and PCB guy too.
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Old 24th Aug 2018, 10:02 am   #89
SiriusHardware
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Default Re: MK14 schematic revisions

The one in the manual is actually switched as well, so you can swap between Single Step and normal running.

If you use your MK14 from time to time (rather than just maintaining it in running order as a museum piece) the 'New' OS is a big improvement over the old, requiring fewer keypresses to enter each byte of data and also incorporates the support routines for the tape interface (easily built on a bit of veroboard) and a handy jump offset calculator.

I'm surprised to hear that an issue V MK14 would have the 'old' OS, which is distinguished by the fact that it starts up with a '---- --' prompt, rather than the '0000 00' prompt of the 'new' OS.
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Old 26th Aug 2018, 9:27 am   #90
Pepperm
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Default Re: MK14 schematic revisions

It is all a learning exercise for me even all these years later, it would see. When I built the kit I never knew that I had anything other than the same version as everyone else, but as my kit starts up with 0000 00 and the board says V on it I must have the later version or the ROM. Hope it works with my replica Version I board...
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Old 26th Aug 2018, 9:46 am   #91
SiriusHardware
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Default Re: MK14 schematic revisions

Quote:
Originally Posted by Pepperm View Post
I must have the later version or the ROM. Hope it works with my replica Version I board...
It does, you just need to tie Sense-A low if you do not add the optional single step hardware. Otherwise I think you will be able to enter code OK, but you won't be able to run it.
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Old 7th Sep 2018, 9:38 pm   #92
Pepperm
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Default Re: MK14 schematic revisions

Well after some head scratching I now know what you mean. The trouble is that the Mk14 I purchased is a Rev V board with a V2 OS, but I was supplied with a manual for V1 OS. That explains why I spent lots of time correcting the manual all those years ago...
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Old 7th Sep 2018, 11:30 pm   #93
SiriusHardware
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Default Re: MK14 schematic revisions

There is an excellent pdf copy of the late version MK14 manual on Martin Lukasek's website here

http://www.8bity.cz/files/MK14/mk14ManualV2_OCR.pdf

That is the version of the manual you need to work with if your MK14, whether early issue or late issue, has the 'new' OS, as it correctly describes the operation of the machine with the new OS.
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Old 11th Sep 2018, 3:26 pm   #94
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Default Re: MK14 schematic revisions

Thanks for that, I've been looking for a manual for the v2 rom. Update: My replica mk14 isnt working, I'm not seeing any bus activity so its either a board wiring issue, bad crystal or bad sc/mp.... I've got a spare processor on the way so may be able to report soon!
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Old 11th Sep 2018, 10:26 pm   #95
SiriusHardware
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Default Re: MK14 schematic revisions

Silly question, but is your original SC/MP an SC/MP II? The original SC/MP only operates up to 1MHz as far as I know. SC/MP II is up to 4MHz, although of course Clive chose to overclock it slightly, mainly because 4.43Mhz crystals were widely used in colour TVs and therefore cheap.

If you can tolerate the delay / risk involved in posting chips back and forth - an activity I know you are no stranger to - I'd be happy to test any suspect ICs in my MK14.

The crystal you can test independently by knocking up a simple logic IC based oscillator like this one, attached, found as a web image. Alternatively just fit any crystal you can find in the range from 1MHz to 4MHz in the MK14 - if your original crystal is at fault the machine will run with any other reasonable crystal frequency, just not at the normal speed.

Also definitely check the states of CPU pins which can halt the CPU, such as RESET and other less obvious ones.

The actual SC/MP datasheet seems quite hard to find, here it is presented in unconventional one-page-at-a-time html format, which is better than nothing.

http://searle.hostei.com/grant/SCMP/index.html

SC/MP applications handbook packed with all sorts of SC/MP information here on bitsavers:

http://bitsavers.trailing-edge.com/c...book-Feb77.pdf
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Old 12th Sep 2018, 1:44 am   #96
Slothie
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Default Re: MK14 schematic revisions

Yes, its a SC/MP II, I just looked at it and its marked ISP-8A/600 which is a SC/MP 2 according to wikipedia. I'll hopefully be able to give it another look with the 'scope soon, and maybe breadboard an oscillator as you suggest.I've also got some 1 mhz & 4mhz oscillator modules which I should be able to rig up as an external clock to test if required.
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