Notices by Charlie Balogh (chainq@mastodon.social)

I involuntarily (cheers @root42!) spent my Saturday on tracing down an ancient Turbo C bug. 😅

The intr() function, used to call DOS/BIOS interrupts will pass the wrong BP register value to the interrupt. BP is heavily used in stack handling, so intr() generates a BP-reload-and-INT-trampoline on the stack, but the BP reload offset it creates is off-by-four.

Fix: Look for the sequence C6 46 F4 E2 in affected binaries, and change E2 to DE.

More details in reply. 🧵

#msdos #retrocomputing

My actual boxed copy of OS3.1. Released by Village Tronic around/right after Commodore's demise. This is for the A4000 only though, so the A600 ROM I burned earlier is technically still pirated. Please address your cease and desist letters to NIL:. #noregrets #amiga