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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 24th May 2020, 3:26 pm   #241
Slothie
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Default Re: Recreating the Bywood Scrumpi

Since A11 is used to select IO then you need to load ox80 into P1 high! Also zero the low byte of p1
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Old 24th May 2020, 3:32 pm   #242
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Quote:
Originally Posted by Slothie View Post
Since A11 is used to select IO then you need to load ox80 into P1 high! Also zero the low byte of p1
See my previous post - that was my first attempt for a long time... glad I am not the only one.
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Old 24th May 2020, 3:33 pm   #243
philoupat83
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Default Re: Recreating the Bywood Scrumpi

Hello
sunmoonstar returns us on the latch he used the display kit of NS for the INTROKIT have found the schemat with ref DM85L51N equivalent of the 74173
so 1-2-15 are at GND
9-10 are together on both Latch on one PAD
7 is well out of IC11 pin4 as you specify
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Old 24th May 2020, 3:37 pm   #244
Slothie
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Default Re: Recreating the Bywood Scrumpi

Hah! Caught out. My only excuse is I've not been near a programmable device in 8 months. And I should read peoples posts more carefully! And as it happens it doesn't matter what's in the low 8 bits either so ignore the whole post!
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Old 24th May 2020, 3:55 pm   #245
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Quote:
Originally Posted by philoupat83 View Post
Hello
sunmoonstar returns us on the latch he used the display kit of NS for the INTROKIT have found the schemat with ref DM85L51N equivalent of the 74173
so 1-2-15 are at GND
9-10 are together on both Latch on one PAD
7 is well out of IC11 pin4 as you specify
Nice find - that is fine as an output like I am doing but, you can also configure one or both as inputs - in that case EO (1 & 2) would need to be high unless selected or it would drag the data bus down so there is a PAD on the Joined Pin 1 and 2 so you can change the configuration as needed. I.e. five pads each side. I will tie my 15 low just in case that is causing a problem.
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Old 24th May 2020, 4:34 pm   #246
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Default Re: Recreating the Bywood Scrumpi

Well - I think that is game over. I started to suspect a fault on the 74LS00 due to the lack of a pulse on NRDS/NWDS at any point - looking at the circuit that would never affect the address selection logic if the output would always be high as there is usually a Read or a Write going on. Swapped over the IC11 and IC2 and now the whole board is dead - even when I put them back. I think I may have a fault that is eating 74LS00 - my last two (previously tested) fresh from the pack do not restore operation... maybe I have fried something else...
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Old 24th May 2020, 5:21 pm   #247
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Default Re: Recreating the Bywood Scrumpi

damage the model will not be able to tell us more i hope nothing serious
i have corrected the latch here is my final plan I transfer on kicad and prepare the gerber for jlpcb I send it Monday
for x I connect it to vcc but with the possibility to cut
Finally we arrive at the end of the recreation. my processor begins to vibrate with impatience
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Old 24th May 2020, 5:41 pm   #248
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Quote:
Originally Posted by philoupat83 View Post
damage the model will not be able to tell us more i hope nothing serious
i have corrected the latch here is my final plan I transfer on kicad and prepare the gerber for jlpcb I send it Monday
for x I connect it to vcc but with the possibility to cut
Finally we arrive at the end of the recreation. my processor begins to vibrate with impatience
I put the suspected faulty 74LS00 back in and it works again, but still no latch - so I just need to make a test harness to see if just those gates are faulty and I have just been lucky until now - if so I will buy another - well I have already ordered a pack of 10...

My chips (CPU and RAM) is now in Stanstead waiting for customs so it is getting closer to me building a SCRUMPI 1 with a 500 as well - I will make the PSU while I wait...

On the PCB I think you misunderstood me IC12 and IC13 should be totally separate so either can be IN or OUT or both can be the same. So I suggest the following (MR should still be tied to ground)

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Old 24th May 2020, 7:22 pm   #249
philoupat83
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Default Re: Recreating the Bywood Scrumpi

Thank you for that clarification that Iíve been waiting for.
1 2 3 awarded tomorrow end of the pcb more modification possible
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Old 25th May 2020, 1:28 pm   #250
philoupat83
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Default Re: Recreating the Bywood Scrumpi

interesting articles to insert in the scrumpi manual
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Old 25th May 2020, 1:32 pm   #251
philoupat83
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Default Re: Recreating the Bywood Scrumpi

see
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File Type: pdf kirkpatrick_article_scmp1.pdf (1.45 MB, 8 views)
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Old 25th May 2020, 1:36 pm   #252
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Default Re: Recreating the Bywood Scrumpi

re see
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Old 25th May 2020, 1:51 pm   #253
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Yes I mention this article in the history section as the news of the SCMP arrival in the UK. I am wary of including full documents due to copyright but, we can leave them here for people to pick up...
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Old 25th May 2020, 3:54 pm   #254
Timbucus
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Default Re: Recreating the Bywood Scrumpi

In terms of the PSU section does anyone have any suggestions on how simple the 12v solution can be - e.g. would the zener need a transistor amplifier or will the SC/MP current drain be so low and constant not to need it the data sheet says typical 100 and max 135? mA so should not vary to much.

On another note I was lucky to secure an original summary card with a NOS in tube SC/MP II last year.

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I have just done a scan of it as I have only ever found a photo of a very bad condition one online anywhere but, yet again it is too big for the forum so I have added it to my GoogleDrive...

SC/MP Instruction Guide
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Old 25th May 2020, 7:21 pm   #255
philoupat83
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Default Re: Recreating the Bywood Scrumpi

this document was provided with an isp8a/500A?
in this case it can be in your biopic
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Old 25th May 2020, 7:56 pm   #256
philoupat83
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Default Re: Recreating the Bywood Scrumpi

an example document provided with the clone of the miniscamp
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Old 25th May 2020, 8:29 pm   #257
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Nice find - some interesting techniques in there - the advert at Nosher.net mentions the set of 8 NIBL proms (without the card I assume) are an eye watering £147.60! That would be about £640 today.

The MiniSCAMP has the advantage as well that the 8 LED's can be used as as simple display as they can be latched to values - I think I have a rough technique for the SCRUMPI but, we shall see how well it works out when I get code running...
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Old Yesterday, 9:06 pm   #258
Timbucus
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Default Re: Recreating the Bywood Scrumpi

OK Good news the alternate AMD9112 chips turned up - same day as the long delayed DM2112 ones... and both sets work fine in the board. Except as soon as I turned off PROTECT to allow some self modify code it wiped RAM. Turned out I was correct and one of the gates on my 74LS00 was faulty as shown by my chip tester. Managed to find one working one in my MK14 VDU kit and now the board works as I expect with some flashy code running to HALT, SINGLE STEP, SLOW - data entry is a breeze now you don't have to pull a jumper wire every time you want to write.

The only problem I seem to have is I still cannot get the latch to work - putting it on the dual scope it is now getting the missing clock pulses I was searching for before since I put in the new 74LS00... should have trusted my kit... it seems that the clock pulse is not arriving while the CS is LOW although it is a little hard to see exactly on a 1979 HAMEG with the Dual Channel being a bit choppy... very retro and authentic diagnostic experience.
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Old Yesterday, 10:15 pm   #259
philoupat83
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Default Re: Recreating the Bywood Scrumpi

hello
super nice try . or did you order the DM2112?
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Old Yesterday, 10:46 pm   #260
Timbucus
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Default Re: Recreating the Bywood Scrumpi

I had previously ordered 2112 chips but, as they were delayed I paid an extortionate amount for a UK supplier - they were late and ended up coming today - the same day the delayed ones arrived so now I have two sets! Ready for my PCB as well

I just wish I could get the latch to work to know we have the circuit correct - I have spent a good part of the evening on and cannot see why it does not work - maybe my latch chip has a fault... but, I have been programming a lot on the board and it all works as I would expect so at least the circuit and the switches are correct.
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