★ APPLICATIONS ★ DIVERS ★ ROMDOS DOS IT ALL ★ |
| Art Studio Loader for ROMDOS | Applications Divers |
Anyone who has invested in a Romboard, ROMDOS and a 3.5 inch external disc drive will not need me to tell them what a wise move it was. If it wasn't for the enormous increase in disc storage capacity which it brings, it would be easy to forget that ROMDOS is at work. And therein lies it's beauty....it's 'invisibility1 makes it a doddle for anyone to use. To achieve this, ROMDOS does not claim any memory for its own use but instead, uses the workspace already claimed by AMSDOS and patches the jumpblocks to intercept calls to disc routines. As a result, any program that works under AMSDOS will work under ROMDOS. But what about those programs that will not run from, or recognise, a ROMDOS format disc? Two notable examples of this type of program are the Advanced Art Studio and Stop Press. The reason that they do not work with ROMDOS is quite simply that they do not look for it. Both these programs use BASIC loaders to get the program code into memory. Control is then passed to the program code with a CALL command. At this point machine code takes over and makes a call to the firmware routine at &BD16 and then &BCCE. And that is where the trouble starts. MC START PROGRAM at &BD16 resets the computer, but stops short of initialising any ROMS (Bye-bye ROMDOS). KL INIT BACK at &BCCE is used to initialise AMSDOS (rom No.7) so that further files or data can be loaded from or saved to disc. This initialisation resets the Disc Parameter Blocks for both drives to their default settings (ie. Normal AMSDOS formats), then selects Drive A and User Area 0. So that's the bad news. The good news is that ifs perfectly possible to write a Poke to give “serious" users infinite lives just like the “gamers” get in Cheat Mode. Infinite lives? Well how about “ROMDOS compatibility". It may not sound as exciting but it's probably a lot more useful. All that is needed is an extra bit of code to initialise ROMDOS immediately after initialising AMSDOS. And lo and behold, here is just such a poke ....
By Jess Harpur of WACCI & Campursoft, AA
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