Out of curiosity on various fast load mechanisms, I actually produced a partial commented disassembly of this format last year. The system supports 4x or 6x speeds.
Here is the disassembly of the bootloader:
I don't have the printed instructions for the program but followed the instructions in the REM at line 200. I managed to create a fast load version of 3D Monster Maze. Here is the wav file I created:
It can be loaded into EightyOne as follows:
- Configure EightyOne to load from Wav file and at normal speed
- Type LOAD ""
- The Bootloader routine loads in and runs
- Continue to play the tape
- The high speed data of 3D Monster Maze will then be loaded in
- Type SLOW
- Run program using RUN 1015
I found the program loads back in in FAST mode, so you need to manually select SLOW mode. This could probably be done by modifying the bootstrap loader, as could making the the fast load encoded program read in auto-run, e.g. add these lines to the bootstrap loader before saving it out:
120 SLOW
130 RUN
If I recall correctly:
- You load in the Bootstrap Loader
- Delete line 200
- Add the two lines above if desired
- Edit the file name in line 100 to be whatever you want, e.g. I set it to "3D MM" for the above
- Type CLS
- Type GOTO 1 to save out the Bootstrap Loader to tape
- Reset the ZX81
- Now load in the Monitor program (as it is the thing that will encode your program into the high speed format)
- Press U to load any program then Y
- Load in the program you wish to have converted to the high speed format
- Once loaded, I think it provides an option to save out at your preferred speed
- You save the program out after the Bootstrap Loader you saved out earlier
Just tried it again but can't get the Monitor to load in a program. Somehow I got it to work before but I don't recall any more details. Hopefully someone will have the instructions you are after.
