Re: [Sdcc-user] quesiton about z80

[Richard G. <ri...@re...>]

The true "hardware debugger" is a logic analyser I suppose - that's what I 
often use. One can see all traffic on the various buses using one of these, 
and for 8-bit stuff one can pick them up quite cheaply on eBay.

The other way is an in-circuit-emulator, but that will still use an RST 
instruction so that the debugging code can take over, however temporarily.

Another way I read about YEARS ago in relation to the Z80 was to use the M1 
signal (first instruction byte fetch) and an interrupt (NMI?) - as a 
single-stepping type of function. I have a book somewhere on this, I'll see 
if I can find it... this would obviously need some additional logic to 
implement.

On Saturday 28 March 2009 23:00:28 bo...@co... wrote:
> ----- bo...@co... wrote:
> > Now if you really want to know what the SP was when it
> > hit a breakpoint (IOW, which breakpoint did you hit?), then
> > the standard way to do that on z80 is to use restart inst.,
> > and then look on top of stack.
>
> Make that:
> Now if you really want to know what the PC was when it
> hit a breakpoint (IOW, which breakpoint did you hit?), then
> the standard way to do that on z80 is to use restart inst.,
> and then look on top of stack.
>
> (Now, I'm off to the store for caffeine!!!)
>
> Randy

-- 
Richard.
PGP Key-id: 0x5AB3D350

America may be unique in being a country which has leapt from barbarism
to decadence without touching civilization.
		-- John O'Hara