Hot Z II uses a fascinating “trick” for getting back into itself if you should stumble into the error restart, RST 08. This is done by jimmying the ER_SP system variable. For a graphic demonstration, type 0676 (disassembly mode), then go to edit mode and run the code starting at this address (shift R). Dumps you right back into BASIC, doesn’t it?
Now enter any command with a syntax error. For example, LET, PLOT, etc. without a valid argument. WoW!
Want to see how it’s done? Enter 5800 (cold boot initialization), then flip to the next page using ENTER. Change the command, LD HL,HZET to LD HL,CHOO. You can now stumble into an error restart without messing up your names files, etc. Can anyone out there work out a two-way “door” between BASIC and machine-code using this gimmick? -fn