Enhanced Pico-Dos

[bxdanny]

A lot of software for the C1P (and the C2-4P/C4P) was not compatible with the 65D disk system, but I think it is still desirable to be able to load it from/save it to diskettes (or diskette images), rather than having to use ASCII listings, even if the simulated "tape" files are a lot faster than actual tape cassettes were. OSI did have a system for storing programs for "cassette" machines (at least the C1P) on disk, but it saw little use. It was called Pico-Dos, and it simply added two commands to the ROM Basic, LOAD <n> and SAVE <n>, where <n> was a number from 1 through 8. When I added a 610 board and floppy drive to my C1P, that was all it came with. And while I quickly obtained copies of OS-65D from other users, I thought that the Pico-Dos was still a good idea, and decided to add features to it. When I had my old C1P disks converted to emulator files (thanks again, Mark), I continued to work on it, and this is the result. The main added feature is that it adds backspace capability to the C1P under ROM Basic, but there are several others, as listed in the included documentation. There are also several possibly interesting programs included in the attached disk image. These include two programs I wrote that were sold by Orion Software Associates (a disassembler and the game Mini-Gomoku) and the original C1P version of Monster Maze by Dave Edson. This version of Pico-Dos runs both on the C1P, and on the C2-4P/C4P with Cegmon installed.

[bxdanny]

When I added backspacing to Pico-Dos, my thoughts were that that would be just an interim step, and that if possible, I wanted to add full editing capability, similar to that in 65D 3.3 and the version I added to 65D 3.2. I have now succeeded in doing that.

How is that possible, since the Basic is in ROM? The answer lies in the call to the JMP instruction at location 3 that is used to issue the OK prompt. By hooking that, I can execute other code whenever the 'OK' prompt is displayed. The disk image attached to this message is basically the same as the one attached to the parent message, except that Program 6 (which had been Ridge Cruiser) has been replaced with a program that loads the Editor. Once run, typing an exclamation point and a line number after an 'OK' prompt brings up the line for editing. The only catch is that, before you can edit a second line, you need to execute some statement so that 'OK' is displayed again. The easiest way is simply to type a question mark and <enter> to execute the statement PRINT (or use "?;" for PRINT; to reduce the number of lines that screen scrolls). If you forget and get an error message, that includes the 'OK', so it will work on the second try.

Source code is included (such as it is). I did add a few comments (and delete a couple of confusing ones), but there still are not a lot.