OK I did a bit more looking this morning with a fresh cup of coffee. ZGBASM uses RST4. It drops an RST 4 into the code, and RST 4 eventually hits a software hook, which then is redirected to ZBGASM, to process the breakpoint, repair the code etc.
Interesting! On Wed, Sep 16, 2020 at 1:05 AM Philip Avery <[email protected]> wrote: > Perhaps instead of single-byte RST 7 it inserts a JMP 'to debugger' at the > breakpoint. Then when the breakpoint is reached it reinstates the original > 3-bytes there. > > Philip > > On 16/09/2020 3:51 pm, Stephen Adolph wrote: > > So, I am trying to understand how the Radio Shack debugger / Assembler > manages to set breakpoints. > Anyone familiar with how to do that? > > In CP/M, the debuggers use RST7. RST7 opcode is placed into the program > to trigger the debugger. > > In M100, such a trick can't work. So, how does the debugger interrupt > the program? > > Also, ZBG.BA, ZBG.CO and the manual seem to be missing from net. Can't > find them anywhere but via the archive: > > > https://web.archive.org/web/20111117155020/http://www.xibalba.com/website100/software.html > > maybe we need to post these up at club100. > > Steve > > >
