Here I am attempting to document a very old project of mine. I wrote
this program to utilise the Tandy Colour Computer, in a way I was used to
with my old MC6800 microprocessor based projects. I think I finished
Colourmon 1.2 in January of 1983. The previous versions had some
programming flaws.
The basis for this machine language monitor is similar to MIKBUG for
the Motorola D1 evaluation kit. This printed circuit board had a Motorola
MC6800 processor and the ROM provided had a simple machine language monitor
program to enable small machine language programs to be entered via the
keyboard of the teletype or loaded via 8-bit paper tape.
In Colourmon, a few improvements were fashioned and advantage was taken
of the ability to write relocatable code with the MC6809E processor, used on
the Tandy Colour Computer. This enabled a shift command to be implemented,
and the ability to use the offset option on the Tandy Color BASIC cassette
tape binary load command. Also the stack was used for any temporary memory
variables, making clandestine use easier.
The first version was available at location 3000 hexadecimal, to suit
the old 16K memory map, but it wasn't long before 7000 hexadecimal became
the best location for the 32K (64K) memory map. I made up a few cassette
tapes for the local software seller, but he sold none that I knew of.
Colourmon 1.2 turned up in a few locally released disk controller packs.
Rainbow Bits from The Gap Queensland, put out a Rainbow Bits 1.4 Expanded
disk BASIC, disk controller for the colour computer I or II, and in spare
bytes in the disk controller ROM contained a butchered version of Colourmon
1.2. They had actually prevented the shift command from working correctly,
but that didn't matter since in ROM, Colourmon was pretty safe from being
clobbered. DDOS3 Version 1 (1987) had a exact copy of Colourmon 1.2 in it,
and worked fairly well but ROM switching meant that it was not always in
memory.
I can only show the original cassette tape version of the operating
instructions and the assembler listing. The operating instructions initially
eluded me, but I found them on a cassette in CCWRITER format.