CPLD replacement for ZX8301

[dilwyn]

All these Orange jokes are a bit of a g-rind. Although a bit a-peel-ing.

[NormanDunbar]

Toodle pip!

[lliont]

Photo converted for the QL with the help of Gimp and a little C# program I wrote.

[XorA]

1675466692881.jpg


Photo converted for the QL with the help of Gimp and a little C# program I wrote.


Greece.jpg

Nice, if you replace sqlux-pallette.png with your pallette this https://github.com/xXorAa/ql-picture program will convert photos to _scr files!

[lliont]

This works nice

scart_con.png (10.01 KiB) Viewed 2407 times

[ones' complement]

R88 on my QL is 75ohm (Violet/Green/Black).

[lliont]

I Know, but change it to 47 if you ever use my board and this mod for better results

[ones' complement]

Maybe a 100ohm preset ?

[bwinkel67]

I have a question about the other ULA on the QL. How different was the ZX8302 from the ZX 1 Interface ULA? Seems like they both did similar things in controlling microdrives, serial communication, and networking, right? So it's on the interface to the QL side that things would be different (i.e. the QL talks to the chip which controls those devices). I ask because there is a ZX 1 Interface ULA replacement by Charlie and I'm curious how much work would be needed to create a ZX8302 replacement, which is now the last chip on the QL that doesn't have a substitute.

[Pr0f]

those chips are a world apart.

The inteface 1 ULA did not do much in other than offer some connection ports - the actual 'control' of the network ports, serial port was all done with software in the ROM in the Interface 1, I don't think much more assistance was provided to the Microdrive interface either.

The ZX8302 does have some registers, and devices built in that do a bit more than with the data before the QL's micro needs to get involved - perhaps with the exception of the QL network ports - which I think were still bit banged in the end.

From memory:

2 interleaved shift registers for data reception and transmission for Microdrive data
Microdrive motor selection logic
Microdrive Write inhibit (not implemented in the end on the chip)
4 byte binary counter with battery backed capability for the QL clock (battery backup never worked as resetting the computer often corrupted the counter)
Serial transmission shift register (the IPC handled serial reception)
Bit banged interfaced for the QL network
Bit banged interface for the IPC (that handles keyboard and sound)

I believe there is a thread on here by Nasta about the ZX8302