CPLD replacement for ZX8301

[lliont]

Very good!
Try the last version of program for your pcb version I attached. I fixed a video bug since we talked.

[lliont]

Hint for those that are going to build it.
It's better not to solder the header for the programmer or the QL case won't close and you'll have to de-solder or cut the pins.
Just insert it in place and while programing press slightly sideways in order to make good contact for the few seconds the programming lasts. Then you remove it.

[lliont]

Very good!
Try the last version of program for your pcb version I attached. I fixed a video bug since we talked.

After that for this version of pcb do a poke 98400,2 or 4 or 6 or 8 up to 14 and go to mode 4, you should see different colors.

Also although it is an older version pcb you can take the signal from JP1 and mix it with the other colors on the QL motherboard using 3 resistors as discussed at a previous post to get the 16 colors in mode 8.

[Derek_Stewart]

Hint for those that are going to build it.
It's better not to solder the header for the programmer or the QL case won't close and you'll have to de-solder or cut the pins.
Just insert it in place and while programing press slightly sideways in order to make good contact for the few seconds the programming lasts. Then you remove it.

Hi,

I could batch produce the PCB, getting the SMD components soldered by the PCB manufacturer, leaving the Through components to be hand soldered.

With regards to programming the CPLD, probably a POGO pin clip would be the best solution, which does not require a pin header to be soldered in.

[lliont]

If there is interest do make a batch, I'm not interested since I got a working one.

But @everyone interested, please be sure you understand what this is. It is mostly a ULA replacement.
It offers a few new features as 8 palettes choice for mode 4 that will work without any modification.
To use the 16 colors mode you need to add a new connector to QL, this could be RGBS (for scart) or commposite video.
The easiest to add is the composite video by modifying the rf rca to output composite video.
S-video could also be implemented but I didn't place pads for this at the pcb.

Also there is no software except the 2 super basic commands I made for the 16 colors mode.

I forgot to mention there are also 8 variations of the 16 colors controlled by bits 6,5,4 of the register at 98401.

I will help but I won't be responsible for anything going wrong, build it and use it at your own risk.

[Derek_Stewart]

Hi Leon,

Can you give me information on the addtional RGBS connection required for the extra colours.

Could the QL RGB socket not be used, as it has RGB, Composite Sync?

[lliont]

Hi

QL's RGB connection is digital with 3 digital signals you can only have 8 combinations-colors.
To produce the 16 colors you either need an extra digital intensity signal but then you need one of the old RGBI monitors or you need to make analog RGB signals.
I do the analog thing, I mix the flash signal to the RGB signals with a simple resistor network and bring the voltage level down as scart needs it. This way I also can have more then 16 colors to choose from. (I use 3 copies of the ex-flash signal that I can control).
I also provide the correct level csync and a blanking signal to switch the scart input to rgb mode.
I think there are devices that will convert this RGBs signal to VGA or HDMI if one needs that.

So you can't use the QL's socket unless you de-solder it from the motherboard and solder my wires, and this is not nice.

One thing I could do is to feed the new RGB and csync signals to the motherboard, that is a solution. Maybe I do that in a new version PCB ?
Only this won't be nice for those with original QL Monitors. So 2 versions will be needed or I could put jumpers on the pcb to choose the output.

SCART.png (35.2 KiB) Viewed 644 times

[lliont]

How many more pcb versions do I have to make, I thought I finished.

I have my QL from when I was young and I already made holes on the case for switches for eprom selection and toolkit on-off.
I'm not going to sell this QL and I don't care if it looks perfect and so I can make one more hole for a new connector but I respect those who don't like to mess with the case and I'll see what I can do.

I have to consider what other implications may occur if I feed RGB and CS of a different level to the motherboard, a sure one is that QL's standard composite video output will be affected.

[tofro]

How many more pcb versions do I have to make, I thought I finished.

I have my QL from when I was young and I already made holes on the case for switches for eprom selection and toolkit on-off.
I'm not going to sell this QL and I don't care if it looks perfect and so I can make one more hole for a new connector but I respect those who don't like to mess with the case and I'll see what I can do.

I have to consider what other implications may occur if I feed RGB and CS of a different level to the motherboard, a sure one is that QL's standard composite video output will be affected.

One way out (of the QL case ) could be re-wiring the QL Monitor output to carry intensity on pin 3, which is (at least on some versions) normally a monochrome composite signal. This would make the pinout identical to the ZX Spectrum 128 (Toastrack), so the same video cables could be used. I've never used pin 3, so it might be worthwile checking what other people have done.

[lliont]

One way out (of the QL case ) could be re-wiring the QL Monitor output to carry intensity on pin 3, which is (at least on some versions) normally a monochrome composite signal. This would make the pinout identical to the ZX Spectrum 128 (Toastrack), so the same video cables could be used. I've never used pin 3, so it might be worthwile checking what other people have done.

This is a great idea and can be implemented without making a new pcb!

One has to take out the pin of R88 (QL motherboard) that leads to pin 3 and connect a wire from a point on the pcb that flash signal exists (R4) to the R88 pad.

The only feature that won't work is the 8 variations of the 16 colors but they are not significant, there are only slight differences between them.

I'll make the cable to test it. Where can I find it, I'll search the internet.