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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 23rd May 2020, 5:37 pm   #221
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Also the CONT input needs to be at +5v - you could just continue the track and join to the top of R11 which it seems from the SunMoonStars image is what happens.
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Old 23rd May 2020, 6:29 pm   #222
philoupat83
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Default Re: Recreating the Bywood Scrumpi

and what is the purpose of the X pad
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Old 23rd May 2020, 6:36 pm   #223
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Default Re: Recreating the Bywood Scrumpi

it is a mystery... X marks the spot - I have no idea I have been wondering that myself.
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Old 23rd May 2020, 6:41 pm   #224
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Default Re: Recreating the Bywood Scrumpi

answer me quickly for the modifications I am obliged to do in eagle and to start again after in kicad
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Old 23rd May 2020, 7:32 pm   #225
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Default Re: Recreating the Bywood Scrumpi

for latch connection 1-2-15 gnd on both? connection 9-10 also on both
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Old 23rd May 2020, 7:41 pm   #226
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Default Re: Recreating the Bywood Scrumpi

I am not sure yet on 15 only just finished wiring up a socket And wires for the io chip - Need to write some code to test. Yes on the others they are not to Ground you connect either one or the other depending on if it is in or out I think
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Old 23rd May 2020, 7:50 pm   #227
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Default Re: Recreating the Bywood Scrumpi

It is up to you to decide
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Old 23rd May 2020, 7:50 pm   #228
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Default Re: Recreating the Bywood Scrumpi

I have the same doubts as you
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Old 23rd May 2020, 7:54 pm   #229
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Quote:
Originally Posted by philoupat83 View Post
It is up to you to decide
No pressure then
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Old 23rd May 2020, 7:58 pm   #230
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Default Re: Recreating the Bywood Scrumpi

Meanwhile perhaps you would like to check version 2 of my work... still to finish the IO chip section perhaps with some example code.

Too big for the forum so I will put it on my Google drive...

The Soul of an Old Machine DRAFT V2
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Old 23rd May 2020, 8:30 pm   #231
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Default Re: Recreating the Bywood Scrumpi

Just read it through, the only thing I would suggest adding is a section with a more elaborate description, including circuit diagram, of the power arrangement needed to power the SC/MP 1, with Phil's 'Proper' PSU with a centre tapped transformer and +/- regulators and the simple / crude alternative using only 12V and a Zener both shown. Leave it up to the reader to decide which one to use.

This exotic early power supply requirement may be foreign even to many people who have quite a bit of experience with microprocessors generally.
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Old 23rd May 2020, 8:31 pm   #232
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Default Re: Recreating the Bywood Scrumpi

Perfect you worked well.
waits for corrections for the definitive pcb
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Old 23rd May 2020, 8:57 pm   #233
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Quote:
Originally Posted by SiriusHardware View Post
Just read it through, the only thing I would suggest adding is a section with a more elaborate description, including circuit diagram, of the power arrangement needed to power the SC/MP 1, with Phil's 'Proper' PSU with a centre tapped transformer and +/- regulators and the simple / crude alternative using only 12V and a Zener both shown. Leave it up to the reader to decide which one to use.

This exotic early power supply requirement may be foreign even to many people who have quite a bit of experience with microprocessors generally.
Yes - good idea - as I have not built one yet either it will be a good check of what I have written. I will do so for the next edition.

At the moment still trying to work out how these latch chips work - I realised I had no connection to the data bus which was my first mistake, the second was I wired R/W to their CE... getting there.
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Old 23rd May 2020, 9:20 pm   #234
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Default Re: Recreating the Bywood Scrumpi

for X it is necessary to confirm if should be at vcc national is not clear sometimes in the air or used or at vcc I look maybe is a cut track
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Old 23rd May 2020, 10:05 pm   #235
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Default Re: Recreating the Bywood Scrumpi

for updating
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Old 23rd May 2020, 10:23 pm   #236
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Default Re: Recreating the Bywood Scrumpi

for scrumpi 2 it is not a diode but the capacitor of 10nf compensation pin5 but have talk about it later finish this project
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Old 23rd May 2020, 10:27 pm   #237
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Quote:
Originally Posted by philoupat83 View Post
for scrumpi 2 it is not a diode but the capacitor of 10nf compensation pin5 but have talk about it later finish this project
Ah OK I have already fitted one of those to mine anyway - I always do on NE555 to reduce noise.
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Old 24th May 2020, 8:50 am   #238
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Default Re: Recreating the Bywood Scrumpi

Hello
for X I will leave CONT in the air on this pad X.
you work on an 8A600 is no 8A500 more there is a hole in low end side IC13. the pin 15 to well a pad the pin 9-10 also counts 6 pad to the right of IC12
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Old 24th May 2020, 3:11 pm   #239
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Default Re: Recreating the Bywood Scrumpi

Quote:
Originally Posted by philoupat83 View Post
Hello
for X I will leave CONT in the air on this pad X.
you work on an 8A600 is no 8A500 more there is a hole in low end side IC13. the pin 15 to well a pad the pin 9-10 also counts 6 pad to the right of IC12
I would strongly recommend making a PAD next to it available with the track going to +5v so a link can easily be added - mine does not work if I remove the 5v high as both the 500 and 600 data sheet say the same:

"Continue Input - When set high, enables normal execution of of program stored in external memory. When set low, SC/MP operation is suspended (after completion of current instruction) without loss of internal status."

I am still struggling against all sorts of problems to get the latch chips to work: Late nights, lots of coffee, my PC being less reliable than the SCRUMPI (I had three crashes each time I tried to type a document with the program I wrote in - I used a pen and paper in the end), a broken track on my vero (I added a wire link with the machine running not to lose memory again) and I can never seem to see a pulse from NRDS or NWDS or the output of the first NAND IC11 - I think the pulse is just too quick for my equipment to see - I know it must be there as RAM works if it is connected... on top of that software mistakes and hand assembly errors - to set A11 you need to use 0x08 not 0x80 - I keep forgetting about the 12 bit address bus... so my enable never happened to the latch.

I am sure I understand how a D type latch works...

I have wired E0(0&1) to GND to ensure that the output of the latch is always visible as I have that routed to a pair of LED's on O0 and O1.

I have wired D0 and D1 across to D7 and D6 and use the IC11 I/O CS (/CE) on pin 6 to set ED(0&1) Low whenever it is addressed by raising A11. The CP (pin 7) is in theory wired to the Pin 5 (4 on the PCB) input of the IC11 NAND gate input fed from the NRDS/NWDS which means either a write or a read pulse (active low) should act as the clock - that is the one I cannot capture or confirm.

This is my view of the PCB when I looked at it for my veroboard and how I have it - I have had to assume that MR (Master reset) is just unused or pulled LOW (on mine I did nothing and it reads 0v). It is the clock I am not sure I wonder if it is just connected to the CE and the hole is just to allow that to be patched to the EO or ED inputs AS WELL as the Clock (it will trigger as it is exiting the pulse then allowing the Active Low to have given time for the Tri State to be exited - if so it is clever) and my tap from IC11 of the NAND output is what is failing - I will be trying that next but, I am going to turn it off to try that and put the code back in.

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Last edited by Timbucus; 24th May 2020 at 3:23 pm.
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Old 24th May 2020, 3:21 pm   #240
Timbucus
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Default Re: Recreating the Bywood Scrumpi

Here is the code I am using again can someone sanity check...

# Code used for SCRUMPI 1 to test latch wired as Output

00001 C4 LDI 0x08
00010 08
00011 35 XPAH P1 ; We dont care what is in the lower byte
LOOP:
00100 C4 LDI 0x80 ; Bit 7 of the data is the first LED
00101 80
00110 C9 ST 0x00(P1) ; No offset needed again any address with A11 will activate
00111 00
01000 8F DLY
01001 00
01010 C4 LDI 0x40 ; Bit is the other LED
01011 40
01100 C9 ST 0x00(P1) ; Now only Bit 6 is a 1
01101 00
01110 8F DLY
01111 00
10000 90 JMP LOOP (256-14) = 00100
10001 F2

This should cause the two LED's to flash alternately - in single step it will be
very slow...
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