I have an option rom but the bios doesn't boot unless I press the esc-key and the bios calls the option rom. I want to know how the bios calls the option rom without pressing the esc-key? Does it jump into the same entry point? Especially where is the output of the option rom when I can only see the splash screen?
Success! Here is my patch for the misc.bin. I disassembled the misc.bin and permantently activated the esc-key sequence so it bypass the loading error.
seg000:016B loc_16B: ; CODE XREF: seg000:00BBj seg000:016B call sub_CB0 seg000:016E mov ds:byte_5A24, 0 seg000:0173 push bx seg000:0174 call sub_DFE seg000:0177 pop bx seg000:0178 nop seg000:0179 nop seg000:017A call sub_26C seg000:017D call sub_1F0 seg000:0180 mov cx, 0BB8h seg000:0183 seg000:0183 loc_183: ; CODE XREF: seg000:019Cj seg000:0183 mov ah, 1 seg000:0185 int 16h ; KEYBOARD - CHECK BUFFER, DO NOT CLEAR seg000:0185 ; Return: ZF clear if character in buffer seg000:0185 ; AH = scan code, AL = character seg000:0185 ; ZF set if no character in buffer seg000:0187 jz short loc_199 seg000:0189 xor ah, ah seg000:018B int 16h ; KEYBOARD - READ CHAR FROM BUFFER, WAIT IF EMPTY seg000:018B ; Return: AH = scan code, AL = character seg000:018D cmp ax, 2106h seg000:0190 jz short loc_1A0 seg000:0192 cmp ax, 1519h seg000:0195 jz short loc_1A0 seg000:0197 jmp short loc_1BD seg000:0199 ; --------------------------------------------------------------------------- seg000:0199 seg000:0199 loc_199: ; CODE XREF: seg000:0187j seg000:0199 call sub_2318 seg000:019C loop loc_183 seg000:019E jmp short loc_1BD seg000:01A0 ; --------------------------------------------------------------------------- seg000:01A0 seg000:01A0 loc_1A0: ; CODE XREF: seg000:0190j seg000:01A0 ; seg000:0195j seg000:01A0 mov ds:byte_5A5B, 1 seg000:01A5 mov ds:byte_573C, 0 seg000:01AA mov ds:byte_5A22, 0 seg000:01AF call sub_27E seg000:01B2 mov ds:byte_5A21, 3 seg000:01B7 mov dx, 8 seg000:01BA jmp loc_2ED seg000:01BD ; --------------------------------------------------------------------------- seg000:01BD seg000:01BD loc_1BD: ; CODE XREF: seg000:0197j seg000:01BD ; seg000:019Ej seg000:01BD call sub_F67 seg000:01C0 retf