Denial

Link to the PRG?

There might be a problem with limiting the values in the CRT emulation, so something overflows.

It's basically a matrix of 8x8 resistors, 8 current sources, 8 current sinks (and all of them programmable as either source or sink) - not trivial at all

I have implemented (partial) emulation of the Keyboard matrix quirks some years ago - indeed only for C64 (and C128 i believe). Even for those, it doesn't really work right in all cases (but good enough for 3 keys i think). It's quite a surprisingly complex problem unfortunately :) So no, you are no...

It'll work - mostly - if you don't connect anything at all to the 9VAC pins. That voltage is used on the user port for things like RS232 and some modems, and also for the datasette motor.

VIC20, yes

rhialto made a quick patch

http://www.falu.nl/~rhialto/watchpoints1.diff.txt

eg

break load 0 $ffff if @cpu:(pc) < $80

BTW, i am offering a crate of beer to whoever implements a "dereference" operator for the conditions (so you can use the content of the memory whatever expression points to) - that would be super useful indeed

Can the value of the memory at PC be used?

Unfortunately not

I don't think this can be done directly (please correct me if i am missing something) - you can only compare registers and memory locations, there is no way to tell "was pulled from stack". Perhaps you can do something like ($100+SP)=$55 && A=$55 (which is obviously not really what...

Next step would be unrolling the loop for each needed slope... perhaps not on VIC20 though

Raster tricks are actually easier than on VICII - since there are no "bad lines". Very straight forward

I don't think you'll fry something - but it will not work

Also I know the C64-fastloader Spindle uses illegals to do GCR-decoding on the fly which was deemed impossible before.

All the modern loaders do

but there does exist software that uses the so-called "illegal opcodes". To add to this: not seldom in old games there are undocumented opcodes executed not because the coder used them intentionally, but because they are a result of accidental memory corruption during development. (This i...

This is really very cool. Imagine showing this to ppl back in 1980 :=)

As said on Lemon - can't you simply use it as is? The binary format should be the same