First post, by videogamer555
It seems to have a problem with interrupt 13, which is direct disk access. I'm trying to create my own program that runs at boot-up. I'm testing it in DosBox by using DosBox's boot command to boot the disk image that contains this program (which I've written in assembly language, using NASM). One of the first things it does is attempt to load additional data from the disk, with a call to interrupt 13 with register AH set to 2 (and the other registers set to read the first 125 sectors from the disk). But it doesn't work. When I try it in the debug version of DosBox, I see why. It is giving me an "Illegal unhandled interrupt D" error. D is the hexidecimal representation of the number 13. Interrupt 13, is not even a DOS function. It is a BIOS function, the lowest of all "low level" computer code, which means that ALL x86 computers are supposed to be able to handle it. In fact it's with interrupt 13 that all disk operations are ultimately performed. Even in modern versions of Windows, if you dug down into the Windows kernel, you'd find that functions that read data from the disk are actually calling interrupt, and the Windows API functions like ReadFile and WriteFile, are in fact invoking interrupt 13 deep down in their code. So if interrupt 13 is truly not being handled by DosBox, it's a major bug, because interrupt 13 is necessary for all forms of disk access.
