The Sinclair QL Forum

FrancoisLanciault wrote:Would this project also work with Hermes instead of the IPC 8049 ?

I was going to ask this too. ALl my QLs have Hermes

More to point is it would require bending pin out, not something I would want to do to a reprogrammble 8749. Could do with some PCB wizard designing a small board to breakout other usable pins on Hermes.

Hi,

Way in time, when Capslock LED first appeared, I did not like the idea of bending 8049 pins and soldering to the 8049. So I built a vero board based version, to save bending pins and damaging the 8049.

I have a schemstic done, just need the PCB layout done.

It's a bit cruel, a PCB would be nice and while I had my cheapo camera out... Green LED fits nicely even in Schon keyboard case.

Silvester wrote:It's a bit cruel, a PCB would be nice
DSCF0147s.JPG
and while I had my cheapo camera out...
DSCF0153s.JPG
Green LED fits nicely even in Schon keyboard case.

Hi David,

That looks like my first attempt in 80s-90s, except I bent out Pin 24 unlike in your picture which you have Pin 23 bent out. What is the purpose of bending Pin 23 out?

I later did a veroboard version, that was too big to fit into a QL case, but I had my QL in a Memotech MTX 512 case with rewired keyboard matrix to suit the QL.

Hi,

First attempt at PCB:
Maybe the LED header could be horizontal.

Derek_Stewart wrote:What is the purpose of bending Pin 23 out?.

Since both pin 23 & 24 are interrupt lines to CPU I also bent out other pin (it may have also been used on QL where I used a 74148 priority encoder to use level 5 interrupt). IIRC Hermes uses interrupt generated within ZX8302 from activity on COMDATA/COMCTL line.

I think this could be reduced to a single high efficiency LED and resistor...

Hi,

I revisited this, and updated the PCB layout to have Pin 23 not connected to the QL board.

The 3D view of PCB, without he Socket fitted is:
The LED connection is at the front of the board, this gives possible connection to existing LEDs or a new LED