The Sinclair QL Forum

Ah - 2nd link on this page :

https://www.princeton.edu/~mae412/volume.html

There was a project to provide a computer controlled Zero 1 interface - I think it was a US based project using 6502 - in Model Railway Electronics 1984 edition - can't find the magazine online, but I have a scanned copy in pdf format of the main circuit. You can PM me if interested.

I have been ...

Think of the Aurora as being the same addresses as the QL has in the bottom part of the 1M memory map of a QL - notably ROM area, the QL I/O area and the 64K of video RAM that's in a standard QL AND also as having 240 K in the top 256K, but not in the 1M memory map - the A19=A18 line is actually ...

The chip you replaced isn't required for RGB output - though it may affect it. The fact you are getting to the point of a working command line does suggest that the RAM is probably ok, as the computer would normally stop with a 'video pattern' before that point if it wasn't.

Do you have access to ...

Another trick with axial components like resistors, diodes and the like is to site them in the board, and then solder from the top if it's a double sided board - just one leg. This holds the component allowing you to flip the board and not have any of them move. Then solder away!

It's common in power supplies to see a Diode across the regulator to prevent such voltages damaging the regulator - they are NOT present in the QL circuit.

More details are here:

https://forum.arduino.cc/t/why-to-uses- ... or/1052410

The 9v on the edge connector will feed the regulator with 9V - but that's a long circuit path and was originally specified to provide 9V on the edge connector for plugin cards - maybe allowing 500ma of current to expansion cards with their own regulator. It was not designed to feed 9V to power the ...

Ah - I see someone replied in the time it was taking me to write my reply - lol.

For the IPC > ZX8302 the communication is similar:

;
; Send 8 bits
;
IPC_Send_8:
mov r5,#008H
jmp L0358
;
; Send 4 bits
;
IPC_Send_4:
swap a
mov r5,#004H
L0358:
rl a
mov r6,a
jb0 L0369
L035C:
in a,p2
jb7 L035C
movx @r0,a
anl p2,#07FH
movx @r0,a
orl p2,#080H
mov a,r6
djnz r5,L0358 ...

Looking at the IPC code side - the ZX8302 has to send a 0 bit first - which is effectively dropped, and then the next bit, as either 0 or 1 is stored and rolled round into the nibble that's formed - the start of the loop to read bits coming from the ZX8302 is always waiting for that start bit of 0 ...