Msg: 1784 *Conference*
03-04-92 11:06:49
From: TRACY ALLEN
To : HARVEY CHRISLEY
Subj: REPLY TO MSG #1722 (SARDINE AND SUPERROM)
Dear Harv, A ROM trigger file is a file that has type 240d (F0h). A file that has that type is diplayed on the menu right after the built-in BASIC, TEXT, TELCOM, etc., and it has no extension. When you move the widebar cursor over a file that has the type 240 and press ENTER, the computer immediately jumps (M100,T102) to location 63012. At 63012 are the instructions that disable the interupts, switch to the option ROM, and and then jump to location zero (in the option ROM). There is no "file" as such in the computer. The name on the menu is just a "trigger" to get into the ROM. Hence, "ROM trigger file". ROM files can't be KILLed. The approach taken by TS in its ROMs is to create an actual file on the menu, one that can be KILLed. The contents of the file are usually the single instruction, CALL63012 or something close to that. There are lots of variations. Many ROMs mess around with the actual set of instructions at 63012. A warm start restores those instructions to their virgin state, but every warm start also checks for the presence of an option ROM, and most option ROMs set themselves up to make a bunch of changes in high memory at that time, including changes in the 63012 startup area. Turning OFF a ROM should reverse those changes. Some TS ROMs detect when you KILL their file off the menu. Like in KILL"UR2". The command to kill off the WRITE ROM is CALL63012,0,1. I don't have a SUPERROM myself, but I'm surprised that there isn't something like that to deactivate it. I'm tempted to include someting like your code in the N2X machine language program. That is, it would be code that would scan the directoy and delete (bit 7:=0) any ROM trigger files (type 240) it finds there. But, in this business, there might be some other ROM where that isn't a good way to go about it! Thanks for your feedback! -- Tracy :(eme):