|Re: [hatari-devel] Re: New GemdosParam variable in debugger (was: EmuTOS startup sequence vs. real TOS)|
[ Thread Index |
| More lists.tuxfamily.org/hatari-devel Archives
On Mittwoch, 2. Mai 2018 21:41:58 CEST Eero Tamminen wrote:
> Can somebody explain why e.g. BIOS & XBIOS trap entries don't
> need to do that in Hatari code?
GemDOS_OpCode is executed by emulating the GEMDOS_OPCODE instruction, which is
part of the cartridge code. The code there is executed by the TRAP #1 handler,
and thus already in supervisor mode, after pushing the trap exception frame.
Whereas VDI, BIOS & XBIOS calls are intercepted in newcpu.c, before actually
emulating the TRAP instruction.