Hi, don't get your hopes up yet as I've only just started the code for this and there's
not much to see. I've started this thread as I think I'll have quite a few questions as I work through this and hopefully have something to show by the end of it.

My fist question is about this:

http://codebase64.net/doku.php?id=base: ... iplication

I'm using it for signed multiply of 16bit * 16bit = 32 bit

It seems to all work fine but in the code for generating table 1 there's this:

.db $c9

which I assume is EQUIB &C9 in electron assembler, am I right? and what does it do?

Hi. This sounds like an ambitious project! Will be interesting to see how it progresses.


Yep, that should be an EQUB instruction on the Electron. It's basically an optimisation to reduce the byte count of the code. C9 is the opcode for an immediate CMP instruction. The first time through the loop, the TYA following it is consumed as the operand of the CMP and as a side effect, the carry is cleared. Subsequent iterations branch back to the TYA instruction with the carry already in the required state.

Don't expect anything too great and thanks for the info.