The Sinclair QL Forum

I am building a custom QL keyboard out of a PC gaming keyboard.
The PC keyboard will have 1 more than the QL keyboard. It would be trivial to use that key as a second CTRL or ALT key, but I would rather have a DELETE key that would mimic the CTRL-LEFT
So my question is: Would it be possible? Can I wire that key to both CTR and LEFT keys ? or this kind of wireing would break something in the QL?

CTRL is wired to the keyboard connectors J11 pin 9 and J12 pin1
LEFT key is wired to J11 pin 8 and J12 pin 3
Can I wire a Delete key to J11 pins 8 and 9 and J12 pins 1 and 3 without damaging anything ?

No.
All keys must be wired between one row and one column line.
But, there are keys that have double switches inside, in other words it is like two keys in one. This makes it possible to connect one contact across the CTRL key and the other across the left arrow.
There are also electronic ways to do it, using a CMOS switch chip (4066 or 74HC4066) connected to a normal switch but this also requires providing 5V and ground from the motherboard.

Thank you Nasta.

Here's a ZX81 and Spectrum external keyboard that use extras keys the way Nasta describes

https://worldradiohistory.com/UK/Mapeli ... ook-03.pdf and https://worldradiohistory.com/UK/Mapeli ... ook-09.pdf

IIRC there was something in QUANTA magazine about using 4066 for keyboard, from which I did this back in 1994 to a OPD keyboard.

I did the trick Samsung did on their laptops, using stick on labels to redefine keys legends, worked very well.

Andrew wrote:I am building a custom QL keyboard out of a PC gaming keyboard.

Are you point to point wiring the keyboard to match the QL or are the existing wires close? I have been contemplating the best method to get a better keyboard attached to the QL narrowed down to either wiring like you or putting a PIC in to adapt a synchronous serial keyboard. I think the PIC could then take PC keyboards as well because the QL doesn't write to the keyboard meaning the keyboard is always the master making things simple.

Ruptor wrote:Are you point to point wiring the keyboard to match the QL or are the existing wires close?

I am wiring point to point. It will be ugly, but effective.
Probably the best method would be to have a custom made printed board and solder the key switches on it - but I could not find any local company to do that and ordering to China takes a very long time. Also there is no company in my country that sells switches or keycaps, so those would have to be ordered from China as well, to lower the cost.
I had an old Zalman keyboard that, with lots of hacking and cutting, fits the QL top (also hacked). I also had a QL top case with no keyboard that I could use and hack.
For the keyboard connector I plan to use some 3M adhesive copper foil sticked onto an old keyboard membrane.

Hi,

It seems along time ago, i 1992, I rewrired a Memotech MTX512 Keyboard to suit the QL.

I used wirewrap wire to make the QL kyboard matrix, many tracks on the Memotech keyboard were cut.

I used signal diodes to route the keyboard wires around which allowed 2 wires going one switch, e.g. CTRL C.

It all worked quite well.

I do not remember what happen to thd Memotech case, probably got thrown in a house move, bit of shame...

Derek_Stewart wrote: I used signal diodes to route the keyboard wires around which allowed 2 wires going one switch, e.g. CTRL C.

Can you please explain in detail how you installed the diodes? I would like to route CTRL and LEFT to one switch - and above Nasta explained that this is not possible.
What type of diodes did you used?

HI,

I used a 1N4148 Signal Diode, the idea is to join to signals to a switch but not short them out.

The diode stops reverse signal flow.

Would join 2 connections to one switch without shorting out the source.

I tried some ASCII art, but the Forum software seems to strip out white spaces.