UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers

Notices

Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Reply
 
Thread Tools
Old 29th Mar 2021, 11:52 am   #121
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Also found this on line Micro Switch Keyboard it has a 28pin encoder chip were mine has a 40pin, but same prefix (SW) not sure on the woodwork.


This Doc on Diablo HyTerm model 1620 also looks interesting on page 2-36 and on its talk about the 2-of-13 encoding that is accomplished on the circuit board using the MOS decoder/encoder chip, and chip info on 4-57.
GeraldSommariva is offline   Reply With Quote
Old 29th Mar 2021, 12:06 pm   #122
ortek_service
Heptode
 
ortek_service's Avatar
 
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 629
Default Re: The Transam Triton Personal Computer

That's a good find.
And it looks like this IC was actually made by National-Semiconductor, from the double wavy-line logo on it - Although probably a custom part for Micro-Switch rather than a standard product in their databooks.
ortek_service is offline   Reply With Quote
Old 29th Mar 2021, 1:37 pm   #123
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Found these sensors, which are copies of the micro switch ones

TESLA Hall ICs

and these guys have all four types https://www.hadex.cz/e978-mh3sd2---b...llovou-sondou/.
Attached Thumbnails
Click image for larger version

Name:	Screen Shot 2021-03-29 at 14.26.06.jpg
Views:	9
Size:	143.1 KB
ID:	230433  
GeraldSommariva is offline   Reply With Quote
Old 29th Mar 2021, 2:45 pm   #124
ortek_service
Heptode
 
ortek_service's Avatar
 
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 629
Default Re: The Transam Triton Personal Computer

Good find, and being a plastic moulded-cased shouldn't have issues with IC falling off - Although I presume there's room in the key switches to fit these, as may be a bit thicker.

I presume that distributor will ship to the UK for not too much (Although may now get stung for retrospective VAT & handling fees on any value order from outside the UK, if the seller doesn't automatically add it in advance that some online marketplaces now do), but looks like you have to do your own translation of their website's Czech language).
And hopefully there aren't too many that are broken, otherwise it could cost a bit (not sure if their price was in Euro's, so 3-4 Euros each?), plus a workaround for the Keyboard encoder putting -12V out can be sorted, and it does still produce the right outputs.
ortek_service is offline   Reply With Quote
Old 29th Mar 2021, 3:30 pm   #125
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

If I can not get the encoder to work, I was thinking of a PIC micro controller, I would need 13 input lines and 8 output line.

To catch the 10+ micro seconds key switch pulse, how fast would we need to be scanning the input I/O lines ?

I do want to keep this keyboard if I can, as then I just referb my old case rather than building a new one.
GeraldSommariva is offline   Reply With Quote
Old 29th Mar 2021, 3:59 pm   #126
Mark1960
Hexode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 459
Default Re: The Transam Triton Personal Computer

I don’t think you would scan the inputs the way you would with a typical keyboard matrix.

Maybe interrupt on any active key input, then read the 13 inputs and detect which 2 of 13 to decode the key pressed.

You could also possibly use two priority encoders, one for row and one for column, then combine the output to address an eprom to decode the character pressed.
Mark1960 is offline   Reply With Quote
Old 29th Mar 2021, 4:18 pm   #127
ortek_service
Heptode
 
ortek_service's Avatar
 
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 629
Default Re: The Transam Triton Personal Computer

You'd probably need a tight polling-loop to check row & column lines going low, as might need extra-logic to provide an interrupt. But may not need too many assembly-language instructions instructions in that loop and if mostly 1 or 2 cycles, then may only need to run at a few MHz.

I know you can get DIL40 (but unlikely to be pin compatible with original IC) Atmel ATmega AVR uC's, that will run upto 20MHz and have RISC-like fast instruction set. And I know there are also DIL40 PIC's but may only go upto a few MHz clock speed as I recall there used to be Scenix high-speed ones.
Can also get Silicon Labs enhanced single-cycle C8051's that go upto 50 or 100MHz, ir even a cheap ARM Cortex M0+ etc that go to similar speeds.

The main problem I can see, is that while the processor is outputting (at slower speed?) the looked-up code, it could miss input changes that were being looked-for in a polling loop. So I think it may be best to have a uC that has Input-capture interrupts on all it's I/O pins (assuming that can respond to 10us pulses), for it to detect these, and would also need fairly-fast time to enter the Interrupt Service Routine.

The original IC presumably did it all in Asynchronous logic, so didn't have this issue. So could probably also do it with an FPGA etc, that had enough space for the ROM ASCII etc. look-up table, although these still often require clocking at high rate, unlike many ASIC's.
ortek_service is offline   Reply With Quote
Old 29th Mar 2021, 4:40 pm   #128
Timbucus
Heptode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 923
Default Re: The Transam Triton Personal Computer

The 40Pin 16F877(A) favored by Karen (and now me) clocks to 20MHZ, looks Authentic and should be able to handle that easily - you could of course have a tight loop checking the two ports very quickly to catch the pulses - it is a simple table lookup then for the code or less than two instructions with the return and then an output to the 8Bit port.

I have not really played with the interrupts but, it has edge detect but, only on one 8 bit port if I remember.
Timbucus is offline   Reply With Quote
Old 29th Mar 2021, 5:02 pm   #129
Mark1960
Hexode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 459
Default Re: The Transam Triton Personal Computer

You would only need to interrupt on either row or column, so edge detect on only one 8 bit port should be ok. Then after interrupt detected, read both row and column, decode and output.

Might also need to use interrupts on strobe from the 8080 to clear ready.

Maybe one of these could be a polling loop.
Mark1960 is offline   Reply With Quote
Old 29th Mar 2021, 8:08 pm   #130
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Do we know what pulse length the Triton expects and is it High low High or Low High Low, I forgot to note what this keyboard was doing before I started taking it apart.
GeraldSommariva is offline   Reply With Quote
Old 29th Mar 2021, 9:18 pm   #131
Timbucus
Heptode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 923
Default Re: The Transam Triton Personal Computer

It expects a high going pulse held as long as the key is pressed.
Timbucus is offline   Reply With Quote
Old 29th Mar 2021, 10:05 pm   #132
Mark1960
Hexode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 459
Default Re: The Transam Triton Personal Computer

Is that even possible if the hall effect switches only generate a 20us pulse each time a key is pressed?

I guess the triton will think the key was only pressed for 20us.
Mark1960 is offline   Reply With Quote
Old 30th Mar 2021, 7:00 am   #133
Timbucus
Heptode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 923
Default Re: The Transam Triton Personal Computer

In this instance probably not - that spec is actually what the George risk did and perhaps some software relied on it but it’s not like there are hundreds if games It will work as my PI uploader / USB keyboard based on Sirius work does it that way and types fine.
Timbucus is offline   Reply With Quote
Old 30th Mar 2021, 10:09 am   #134
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Quote:
Originally Posted by Timbucus View Post
In this instance probably not - that spec is actually what the George risk did and perhaps some software relied on it but itís not like there are hundreds if games It will work as my PI uploader / USB keyboard based on Sirius work does it that way and types fine.
Do we know what the pulse width is on the standard Keyboard ?
GeraldSommariva is offline   Reply With Quote
Old 30th Mar 2021, 3:23 pm   #135
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

My Triton get it working project is on hold now waiting for bits to turn-up, most parts that have been dead are 74 series TTL logic, most expensive so far the vdu chip SFF 96364.

The Key hall effect module photo included , a number of the small chips are just hanging of the small circuit board only being held in place by the clear rubber like glue. so I think there might be an ageing issue with their glob-top compound. so its looking like this keyboard might not make it back to working condition.

Also a large (more than 1/2) number of my 2114 sram chip test out ok at slow speed but fail when running at the full Triton clock speed, there were also some that were just dead. these ram's are over 30 years old is it usual for so many to fail ?


So while I wait for part I thought I brush up on some 8080 assembly programming found my old 8080A-8085 Assembly Language Programming by Lance A. Leventhal book but it's looking a bit tired so lets get a new one.

Looked on Amazon https://www.amazon.co.uk/8080A-8085-...s=books&sr=1-1 but you do get free delivery. I will stick with my old one.
Attached Thumbnails
Click image for larger version

Name:	20210330_151440.jpg
Views:	21
Size:	102.6 KB
ID:	230518   Click image for larger version

Name:	20210330_115209.jpg
Views:	22
Size:	74.5 KB
ID:	230519  
GeraldSommariva is offline   Reply With Quote
Old 30th Mar 2021, 5:28 pm   #136
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 4,182
Default Re: The Transam Triton Personal Computer

I've had more 2114 RAMs (of many brands) fail than any other type of chip. Whenever I get a device that uses them that has 'odd' faults, that's what I check first.
TonyDuell is offline   Reply With Quote
Old 31st Mar 2021, 1:49 am   #137
ortek_service
Heptode
 
ortek_service's Avatar
 
Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
Posts: 629
Default Re: The Transam Triton Personal Computer

If those chips under the clear adhesive / glob-top were silicon die, that was wire-bonded to the pads rather than soldered (Even zooming into image, it's not detailed enough to tell), then the die is usually glued down underneath it. So that adhesive (or solder if soldered) must have failed as well.

They probably haven't made 2114 SRAM IC's in the last 30 years, so all are going to be similar age. But after buying quite a few used 'pulls from sockets' ones, several 10's of these have passed OK on the Arduino 2114 tester board (Which I presume can run these at close to their max. speed). So I must have been lucky to not to have any failures, but I don't encounter these as much as DRAM's - of which I've had lots of 4116 & TMS4532 (already half-failed 4164) failures (although rarely 4816 & 4164's)

Yes, the cost of that book is rather high - even for a used one.
Although its much cheaper (especially for used ones) in the USA, even with delivery to UK selected:
https://www.amazon.com/8080A-8085-As.../dp/0931988101

And could pobably get a whole batch printed for their new cost, with a free PDF of it here:
https://www.pdfdrive.com/8080a8085-a...e34426939.html
ortek_service is offline   Reply With Quote
Old 31st Mar 2021, 8:37 am   #138
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Quote:
Originally Posted by TonyDuell View Post
I've had more 2114 RAMs (of many brands) fail than any other type of chip. Whenever I get a device that uses them that has 'odd' faults, that's what I check first.
What about the 2111-2 ram chips , the Triton used these for its on the main board memory up to 3K with 24 x of these chips.

DO these suffer from the same failure as the 2114's ?
GeraldSommariva is offline   Reply With Quote
Old 31st Mar 2021, 8:42 am   #139
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 6,529
Default Re: The Transam Triton Personal Computer

Several of us recently ordered 2111s (actually the AMD version, AM9111) which were needed for MK14 projects or spares for the same and I think there were one or two failures on arrival - although the seller (certainly in my case) replaced the failed devices without any quibbles and the rest were OK. But yes, SRAMs of that era have a poor reputation for reliability.
SiriusHardware is offline   Reply With Quote
Old 31st Mar 2021, 9:34 am   #140
GeraldSommariva
Pentode
 
GeraldSommariva's Avatar
 
Join Date: Mar 2021
Location: Liphook, Hampshire, UK
Posts: 102
Default Re: The Transam Triton Personal Computer

Quote:
Originally Posted by SiriusHardware View Post
Several of us recently ordered 2111s (actually the AMD version, AM9111) which were needed for MK14 projects or spares for the same and I think there were one or two failures on arrival - although the seller (certainly in my case) replaced the failed devices without any quibbles and the rest were OK. But yes, SRAMs of that era have a poor reputation for reliability.
These 2111 look rare so getting hold of 24 could be very expensive was you seller in the UK ?
GeraldSommariva is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 1:31 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.