UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio 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 1st Sep 2020, 10:51 pm   #461
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

On a related subject of modern boards that use SCRUMPI type ideas (if not the SC/MP instructions) I was interested to come across this Digirule2 which is the subject of a currently running Kickstarter

I have backed one as I might tackle converting KarenO's SC/MP work for the MK14 to it to make a small portable SCRUMPI! I need a project to learn about the PIC... In the comments at the bottom of BRAD's page are some photos of through hole board versions that reminded me strongly of the SCRUMPI...

https://i.postimg.cc/CMCCV4NG/IMG-0999.jpg

Click image for larger version

Name:	IMG-0999.jpg
Views:	24
Size:	112.8 KB
ID:	214758
Timbucus is offline   Reply With Quote
Old 2nd Sep 2020, 9:36 pm   #462
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

A similar binary programmed device we have discussed in this thread I think at some point was the OSI300 from November 1975.

Well I just came across a video showing one operating:

https://www.youtube.com/watch?v=3gEiJiN7TiM

it is 6502 obviously as we discovered but, seeing it in action is interesting and shows that the SCRUMPI was seriously much better - twice as much memory and good quality switches for half the price... $99 would have been around 147 as opposed to the SCRUMPI launch price of only 64.81 - although it was a year later in December 1976.
Timbucus is offline   Reply With Quote
Old 4th Sep 2020, 4:57 pm   #463
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 4,534
Default Re: Recreating the Bywood Scrumpi

Nice video about OSI - I can remember Ohio Scientific but never knew they'd offered such a basic trainer system.

Now all we need is something similar for Acorn computers, no doubt entitled 'From Little Acorns..' and starting with the System 1.

I spent a while looking around the Digirule stuff but one thing I could not see was whether it used the instruction set of an existing uP family or whether it has its own 'custom' instruction set. Did you manage to work that out? I see it's been fully backed, anyway.

From the logo on the main IC (Microchip?) I would say the underlying uP is a PIC.
SiriusHardware is offline   Reply With Quote
Old 4th Sep 2020, 5:27 pm   #464
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

The Digirule is indeed a PIC but, and it does use its own made up instruction set for an imaginary 8 bit uP that is implemented on it - but, as it has a programming interface I was thinking of knocking up some firmware to convert it to an SC/MP! If you look at the picture of the back of the rule on the site they are listed there on the site https://bradsprojects.com/digirule2/

Did you know that the System 1 used 8154 and 571 chips because they were on the MK14 and "around" you can see the interview with Sophie Wilson here:

http://speleotrove.com/acorn/acornHistory.html

This also has the snippet in the table that the MK14 was the architect of its own doom as it was used with its programmer to blow the first PROM's!
Timbucus is offline   Reply With Quote
Old 4th Sep 2020, 5:43 pm   #465
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 4,534
Default Re: Recreating the Bywood Scrumpi

I dare say C.C. had already been thinking about this before departing from SOC and no doubt 'borrowed' some components from work, as one does, for 'evaluation'.

I don't know the S1, does it use the 8154 as part of its main circuit? If so that decision all those years ago will have made it doubly difficult to make an exact System 1 replica now, with both 74S571s and INS8154s being increasingly difficult to get.
SiriusHardware is offline   Reply With Quote
Old 4th Sep 2020, 5:51 pm   #466
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

It uses it only as IO and extra RAM I think, it is a system I have not looked at that much but, the diagrams are here https://www.4corn.co.uk/articles/diagrams/.
Timbucus is offline   Reply With Quote
Old 4th Sep 2020, 6:09 pm   #467
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 4,534
Default Re: Recreating the Bywood Scrumpi

Actually, looking at the main diagram it appears to use TWO 8154s, one 'optional' in the same sense as the one on the MK14, but the other is the basis of the interface to the keypad / display and cassette interface.

I see they did, however, have the sense to make all the bus signals available at the expansion connector as standard, something no original MK14 ever managed.
SiriusHardware is offline   Reply With Quote
Old 4th Sep 2020, 8:37 pm   #468
Slothie
Hexode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 434
Default Re: Recreating the Bywood Scrumpi

The plan was that the "Acorn 1" was a CPU card to be used in a rack-type system, the keyboard/display/tape card was an add-on to turn the CPU card into a stand alone system. My school bought the Acorn-1 with keyboard/display assembled into a card sandwich and I spent many happy hours programming it for parents evening displays etc I remember how much more "powerful" it felt than the MK14 (Which I had also had access to because one of my teachers let us use his) but I was also aware it was a more expensive beast than the MK14.
Slothie is offline   Reply With Quote
Old 4th Sep 2020, 10:25 pm   #469
Buzby123
Tetrode
 
Buzby123's Avatar
 
Join Date: Oct 2011
Location: Culcheth, Cheshire, UK.
Posts: 63
Default Re: Recreating the Bywood Scrumpi

I too had an Acorn Sandwich, but that's long gone now. I also had two unpopulated System 1 PCBs which I sold on eBay about 10 years ago, for 50 each !.
Buzby123 is offline   Reply With Quote
Old 4th Sep 2020, 10:59 pm   #470
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

trev-ham has listed his repro System 1 PCB's at the moment on the Bay - he says that is the last ever batch and there are two sets left if anyone wants to secure some.
Timbucus is offline   Reply With Quote
Old 8th Sep 2020, 9:36 pm   #471
Timbucus
Hexode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 453
Default Re: Recreating the Bywood Scrumpi

Putting this thread a bit back on track (I will create a separate thread to continue any Acorn System 1 posts) worth looking at this post on the PIC14 thread for people coming later for Phil G's PW built SCAMP system which bears a striking similarity of design to the SCRUMPI. The April 1980 MicroBUS was presented by DJD who of course reviewed the SCRUMPI several years before but, it was not his design.

https://www.vintage-radio.net/forum/...3&postcount=58
Timbucus is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 6:36 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 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.