Retro Challenge – The inbetween days

So, after a flurry of activity, blog posts and updates at the start of the month, things have got a bit quiet.

That’s not to say I haven’t been doing anything.  I have.  Lots.  But nothing really specific or bloggable.

Until the batch of PCBs arrive, I am kind of in limbo land.  However, I’ve been looking in to the LED matrix boards a bit more, and working out how I’m going to connect them up (short answer – use breadboards to complete the challenge, but get PCBs made up for long term mounting.).

As the breadboard Z80 runs Microsoft Basic, I have been using that to test out a few bits in terms of orientation of the matrices and the best way to drive them.

0,1 - 1,254 0,1 - 1,1270,128 - 1,127 0,128 - 1,254

I have also run my first ever Z80 assembly language program!

ld a,0x17
ld b,0x64
ld c,0x35
add a,b
sub c

I used to compile it in to


which I then programmed in to and run on

Basically, it loads register A with 23, loads register B with 100, loads C with 35.  It then adds 23 and 100 and takes away 35.  The result (70) is left in register A

Sure, it may not be the most sophisticated program out there, but it demonstrates to me that the tools work!

I’ve got hold of a copy of How To Program The Z80 by Rodnay Zaks, which is supposed to be one of the best books of its time.  So I’ll be reading as much of that as I can before the PCBs arrive and soldering starts.