23rd May 2020, 6:29 pm | #221 |
Pentode
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Re: Recreating the Bywood Scrumpi
and what is the purpose of the X pad
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23rd May 2020, 6:36 pm | #222 |
Octode
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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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23rd May 2020, 6:41 pm | #223 |
Pentode
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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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23rd May 2020, 7:32 pm | #224 |
Pentode
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Re: Recreating the Bywood Scrumpi
for latch connection 1-2-15 gnd on both? connection 9-10 also on both
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23rd May 2020, 7:41 pm | #225 |
Octode
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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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23rd May 2020, 7:50 pm | #226 |
Pentode
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Re: Recreating the Bywood Scrumpi
It is up to you to decide
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23rd May 2020, 7:50 pm | #227 |
Pentode
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Re: Recreating the Bywood Scrumpi
I have the same doubts as you
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23rd May 2020, 7:54 pm | #228 |
Octode
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Re: Recreating the Bywood Scrumpi
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23rd May 2020, 7:58 pm | #229 |
Octode
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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 |
23rd May 2020, 8:30 pm | #230 |
Dekatron
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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. |
23rd May 2020, 8:31 pm | #231 |
Pentode
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Re: Recreating the Bywood Scrumpi
Perfect you worked well.
waits for corrections for the definitive pcb |
23rd May 2020, 8:57 pm | #232 | |
Octode
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Re: Recreating the Bywood Scrumpi
Quote:
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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23rd May 2020, 9:20 pm | #233 |
Pentode
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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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23rd May 2020, 10:05 pm | #234 |
Pentode
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Re: Recreating the Bywood Scrumpi
for updating
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23rd May 2020, 10:23 pm | #235 |
Pentode
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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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23rd May 2020, 10:27 pm | #236 |
Octode
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Re: Recreating the Bywood Scrumpi
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24th May 2020, 8:50 am | #237 |
Pentode
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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 |
24th May 2020, 3:11 pm | #238 | |
Octode
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Re: Recreating the Bywood Scrumpi
Quote:
"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. Last edited by Timbucus; 24th May 2020 at 3:23 pm. |
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24th May 2020, 3:21 pm | #239 |
Octode
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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... |
24th May 2020, 3:26 pm | #240 |
Octode
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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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