History

Peter Weingartner b172a7e086 Rudimentary Interrupts Added first pass of interrupt handling. SOF interrupt for Channel A is working in this test.		2021-09-17 21:40:55 -04:00
..
bios_m68k.c	Additional Devices	2021-09-17 12:01:24 -04:00
Makefile	SYSCALL framework	2021-09-13 13:07:00 -04:00
README.md	SYSCALL framework	2021-09-13 13:07:00 -04:00
startup_m68k.s	Rudimentary Interrupts	2021-09-17 21:40:55 -04:00

README.md

m68k

This folder contains the various source files needed to compile Foenix/MCP for the Motorola 68000 series processors.

System Call Convention

System calls will be made through the TRAP instruction. The caller will be expected to push parameters onto the stack using the VBCC ABI, and then issuing a TRAP instruction.

Stack pointer is A7
All arguments are passed on the stack
Registers D0, D1, A0, and A1 will be used as scratch.
Registers D2 - D7, and A2 - A6 will be preserved by the kernel.
Results are returned in D0.

BIOS

All BIOS calls are issued through a TRAP #13 instruction. Register D0 contains the number of the system call to make.