SWTPC 6800 bios 0 (SWTBUG) is made for a PIA (parallel) interface. bios 1 (MIKBUG) is made for a ACIA (serial) interface at the same address. MIKBUG will actually read the bits as they arrive and assemble a byte. Note: All commands must be in uppercase. See the SWTBUG manual. Commands: B Breakpoint C Clear screen D Disk boot E End of tape F Find a byte G Goto J Jump L Ascii Load M Memory change (enter to quit, - to display next byte) O Optional Port P Ascii Punch R Register dump Z Goto Prom (0xC000)