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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 1st May 2020, 11:15 am   #1
philoupat83
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Default Recreating the Bywood Scrumpi

hello to all
a small compilation
I like this thing
I have an 8a/500 waiting

scrumpi_doc.pdf
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Old 1st May 2020, 2:31 pm   #2
Slothie
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Default Re: Good review of SC/MP.

I always wanted a SCRUMPI. Perhaps there's enough clues here to build a replica...
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Old 1st May 2020, 2:46 pm   #3
SiriusHardware
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Default Re: Good review of SC/MP.

I suppose an adapted version of one of the opto-uploaders would be even more of a Godsend with one of those. You'd just have to set all of the address and data switches and the 'latch' pushbutton to 'open' so it could do its work.

Elektor published a project for a switches-and-LEDs SC/MP-1 system which my mate built and had running some months before Science Of Cambridge deigned to send me my MK14 kit. Imagine entering dozens of bytes of code in that painfully slow way only to have it all vanish the moment you power the system off.

My experience of using that system still looms raw in the memory so I would never be tempted to go back to any sort of 'switches and LEDs' system again, not without some sort of loading cheat available anyway.

That said, it taught me enough about the concept so that when the MK14 eventually did arrive, I understood what I was supposed to do.
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Old 1st May 2020, 5:08 pm   #4
philoupat83
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Default Re: Good review of SC/MP.

yes but it is the charm of this era and as you say a wonderful tool of aprentissage
I also think that a fallback and possible I take all the info and there’s some to but missing the photo on the brass side to have found possesseur sunmoonstar in Canada Roberts Creek, BC I sent an email to his national club no answer can be you will arrive to find I search
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Old 1st May 2020, 8:05 pm   #5
philoupat83
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Default Re: Good review of SC/MP.

I wanted to say hello from the south of France to Slothie
and wished him courage and a good recovery
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Old 1st May 2020, 8:24 pm   #6
Slothie
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Default Re: Good review of SC/MP.

Thank you so much! Recovering well thanks!
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Old 1st May 2020, 9:45 pm   #7
philoupat83
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Default Re: Good review of SC/MP.

happy to have
take I finished my MK14 clone Martin and I will look at this famous SCRUMPI
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Old 2nd May 2020, 2:02 pm   #8
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Default Re: Good review of SC/MP.

I have compiled quite a dossier on this device and have been slowly assembling a history of it - there are quite a few surprises on it which I I hope to put into a coherent document which I will obviously share.

I have also pretty much completed a reverse engineer of the SCRUMPI 1 - these are my notes so far SCRUMPI1BuildNotes.txt

Feelers put out to known owners of them have not resulted in replies as I had hoped to get better scans of the actual PCB for an authentic layout. So for the moment I am just sticking with building on a vero board - my illness happened just as I was getting started so has been on a backburner for a while.

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On the rebuild front due to lack of time I have only managed to make the clock circuit work (on the breadboard in the above photo) to prove my guesses on the resistor values gained from study of the one or two photos online including the one in the above PDF.

Hopefully if others are interested we can work towards a real PCB - I do feel that adapting it to use the later +5v only NMOS version of the Chip is worthwhile before attempting to tackle the slightly more complex II or III for which at the moment the PROM images are missing.
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Old 2nd May 2020, 3:32 pm   #9
Slothie
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Default Re: Good review of SC/MP.

I would recommend using the SC/MP 2 if only because they are much easier to find and there's no real reason to not do it unless you're trying to pass it off as an original.
When I get my laptop after the lockdown lifts I'd be happy to help with a schematic / PCB.
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Old 2nd May 2020, 3:49 pm   #10
Slothie
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Default Re: Good review of SC/MP.

Thinking about it converting from SC/MP 1 to 2 is just omitting the negative voltage generation and connecting the negative to 0v. So one board would do dual duty as i dint think anything other than the processor uses the negative rail.
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Old 2nd May 2020, 4:24 pm   #11
Timbucus
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Default Re: Good review of SC/MP.

Appreciate the offer of help with the PCB layout - not my forte. As you say building in a few links to allow either would be great so that an Authentic original could be made should be easy - in my notes there are a few other gotchas about pullups on lines but again three holes so they can be changed as needed would seem simple. I do have a PMOS device on the way - intended for the final build rather than the vero prototype when I have worked out how to get the +5 and -7 generated.
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Old 2nd May 2020, 5:24 pm   #12
SiriusHardware
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Default Re: Good review of SC/MP.

The National Semiconductor 'Introkit' (also based on the SCMP 1) used an MM5214 PROM which also requires a minus supply. Quite a difficult machine to build an exact clone of, purely on availability of parts.
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Old 2nd May 2020, 5:27 pm   #13
philoupat83
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Default Re: Good review of SC/MP.

a good challenge there is more difference
scrumpi 1 no ROM and 8 control switch
srumpi 2 one Rom monitor (elbug kitbug?) 9 switch
the plan of the mini scamp gives a track for the - 7v but a zener takes the 12v with a resistance I am not fan
compute gives a schemat p11 vol2
a combination of the two and elektor 3/08/78
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Old 2nd May 2020, 11:14 pm   #14
philoupat83
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Default Re: Good review of SC/MP.

for the switches I think in the left right order
Reset-Slow-Step-Run/Halt-SA-SB-Protect(Sleep ?)-Load
your grade is just I think
ci and resistor etc remains to make the plan
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Old 3rd May 2020, 11:08 am   #15
philoupat83
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Default Re: Good review of SC/MP.

hello
an interesting document
Attached Files
File Type: pdf MM5214 ROM to Intel 2716 PROM Adapter.pdf (1.42 MB, 42 views)
File Type: pdf MM5204.pdf (167.6 KB, 34 views)
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Old 3rd May 2020, 3:05 pm   #16
Timbucus
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Default Re: Good review of SC/MP.

No the switches are in the order PROTECT SA SB and LOAD as you can see from the photo of the boxed board in your PDF. On the SCRUMPI II the extra ROM/START switch is between the SB and the LOAD.

You cannot see it in the only easily found online photo: http://www.computermuseum.org.uk/fix...home_scmp.html

I did find a better photo here: https://arnowelzel.de/en/jim-austins...#&gid=1&pid=52
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Old 3rd May 2020, 5:05 pm   #17
NealCrook
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Default Re: Good review of SC/MP.

The Register ran an article on the life and times of John Miller-Kirkpatrick, the founder of bywood electronics:

https://www.theregister.co.uk/2013/1...r_kirkpatrick/

Neal.
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Old 3rd May 2020, 5:17 pm   #18
Timbucus
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Default Re: Good review of SC/MP.

That register article is a really good read and gives some excellent clues on the operation of the SCRUMPI 3 (in the photo from the middle of the Manual) which is reviewed in the October 1978 edition of ETI (The issue after the famous Shuttle cover Sept 1978 that reviewed the MK14):

https://www.americanradiohistory.com...1978-10-78.pdf
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Old 3rd May 2020, 6:10 pm   #19
SiriusHardware
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Default Re: Good review of SC/MP.

ASCII Keyboard, 8 line by * 32 character VDU and 64 BYTES of user-available memory??

OK, I see it did allow for the possibility of up to 1K of installed RAM.
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Old 3rd May 2020, 6:20 pm   #20
philoupat83
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Default Re: Good review of SC/MP.

yes is good
ok for SCRUMPI 2 but for SCRUMPI 1 the order of swich is the right one
http://www.sunmoonstars.ca/electroni...computer-1986/
box photo

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the SCRUMPI 3 is great thanks for the info
but what version to make 1 2 or 3
2 seems good to me

although I like the 1 student I was chatting about this thing inaccessible to me

I have an 8a/500 in a drawer

RAM can be replaced by am2112
and the eprom by a 2716
for elektor power supply and good
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