[Coco] CoCo Flash

[Barry Nelson]

 I thought I would mention that after coordinating some firmware changes with Jim Brain, I have been successful at writing some software for his CoCo Flash multi-cart board. Jim had mentioned to me that he intends to show off this new cartridge at the CoCo fest. At the current time the software allows loading up to 32k cartridge images into the flash rom, which can be either DOS images such as HDBDOS or other cartridge images such as games, etc. The default bank has a menu programmed in that prompts you to select which DOS or cartridge you want to start. That cartridge remains active until you either power cycle the computer, or hold the reset button down longer than about 1 second, either of which actions returns you to the selection menu. The selection menu is actually written in BASIC and is easily edited and customized. The menu is loaded from the first bank of the CoCo Flash by a special machine code loader program that loads the menu and starts it. I plan to fully document how it all works to allow the end users to easily customize the menu and the cartridge to their system. In the future I want to see if I can load a ram disk image from the rom cartridge, and have a program to save the modified image back to the rom. Each bank is 4k in size, there are a total of 2048 banks for a size of 8 megs. As an example my own cartridge currently has the following software loaded:

Bank#s	Program
0-1	Menu program, currently only bank 0 is used, bank 1 is reserved for expanding the menu.
2-3	HDBDOS
4-5	Dungeons of Dagorath
6-7	Wildcatting
8-11	EDTASM+
12-15	Tetris
16-19	Demon Attack
20-23	Shanghai
24-27	Thexder
28-35	Arkanoid, 32k rom, started by selecting bank 32
36-43	Rampage, 32k rom, started by selecting bank 40
44-51	RAD Warrior, 32k rom, started by selecting bank 48

This is only an example of what can be done. In addition to loading cartridges, on a CoCo 3 it should be possible to actually replace the BASIC rom as well by placing your own copy of BASIC in a 32k cartridge image. On a CoCo 1 and 2, only 16k of rom is accessible however. I welcome any comments or thoughts as I continue to develop the software for this interesting piece of hardware. My daughter has also been as assisting me in writing some of the software, currently the menu program only display one selection screen, she will be adding the programming needed to display multiple pages of selections. Also needed is a utility to help plan the layout of the cartridge, and work with ccc files. As the flash rom is 8 megs, I have so far only used a fraction of the space available, and even if I add the ram disk image support, it will be challenging to use all the space.