PORTIBM PC Portable (uses same BIOS as XT) 03BC-03BF - PARALLEL PRINTER PORTIBM PC Portable (uses same BIOS as XT) (MDA(Monochrome Display Adapter) A text-only video adapter introduced together with the original IBMInternational Busiuness Machines PCIBM PC. See also CGAColor Graphics Adapter, HGC.'s LPT1) Range: PORTIBM PC Portable (uses same BIOS as XT) 0278h, PORTIBM PC Portable (uses same BIOS as XT) 0378h, or PORTIBM PC Portable (uses same BIOS as XT) 03BCh SeeAlso: MEM 0040h:0008h 03BC -W data port 03BC R- bidirectional port: input from connector unidirectional port: last value written to port 03BD R- status port (see #P0658) 03BE RW control port (see #P0659) Bitfields for parallel interface status port: Bit(s) Description (Table P0658) 7 busy 6 NOT acknowledge (approx. 5us low pulse) 5 out of paper 4 printer is selected 3 *no* error 2 IRQ(Interrupt ReQuest) A hardware line connected to the interrupt controller chip which signals that a CPU interrupt should be generated. has *not* occurred (PS/2IBM PS/2, any model) printer returned -ACK 1-0 reserved Note: if bit 2 is clear (i.e. an interrupt has occurred), it is set again on reading the status register SeeAlso: #P0659 Bitfields for parallel interface control port: Bit(s) Description (Table P0659) 7-6 reserved 7 (see PORTIBM PC Portable (uses same BIOS as XT) 037Bh bit 7) 5 (PS/2IBM PS/2, any model) enable bidirectional port (also requires enabling via PORTIBM PC Portable (uses same BIOS as XT) 0102h) 4 enable IRQ(Interrupt ReQuest) A hardware line connected to the interrupt controller chip which signals that a CPU interrupt should be generated. (via -ACK) 3 select printer (SLCT IN line) 2 =0 initialize printer (-RESET line) 1 automatic line feed 0 strobe (must be set for minimum of 5 microseconds) SeeAlso: #P0658