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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
Octode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 1,893
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
GrahamN
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Join Date: Jun 2008
Location: Burnham on Crouch, Essex, UK.
Posts: 319
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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Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
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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.
Attached Files
File Type: pdf DSA12010005734.pdf (157.0 KB, 9 views)
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