Anyway to break out of the DDT debugger

[ronaldlw]

I've been messing around with the cp/m DDT debugger quite a bit and the most frequent issue I have is not having a breakpoint set at the correct place and having it go off with out a way to get back to the debugger command line.

I've seen some references to a rst 7 button on the control panel, so I'm guessing some systems provided this, but not the imsai 8080.

Is there any way to simulate this with the imsai?

Anyone know of another way to accomplish this?

As I'm writing this it occurred to me that I might be able to use the stop button and then set the address to the rst 7 interrupt handler location. I think that might be problematic though since rst 7 is an interrupt so it'd expect something pushed to the stack. I'll play around with that, but i'm hoping there's a simpler solution :)

[ronaldlw]

I came up with a way but, again, am hoping there's something easier!

1. press stop
2. note the current address and data on the bus
   -have to make sure the system isn't currently executing code in rom, if so run and stop agian
3. enter ff into the data switches
4. press deposit
5. press run
   back in debugger
6. use s to place the original data back at the address modified

[udo-munk]

Unfortunately the IMSAI has no interrupt switch, so not possible without changes. The STEP switch does the same in both positions, it would be possible to cause a RST 7 interrupt for STEP down and single step for STEP up. Don't know if it is possible to modify an original machine this way, in the virtual one it won't be a problem.

[ronaldlw]

ooh, using one of the single step positions is a great idea, is there a feature request list somewhere ?

For now the method i came up with above actually works pretty well, it's so nice not to have to restart and start the process all over again.

[ronaldlw]

Also, for anyone else for whom it wasn't obvious, you can get back to cpm from the ddt debugger by typing g0 which is basically a reset.