2. COSC 456 Lesson 19: Laboratory 5

3. IBM PC Interfacing The parallel port is a 25-pin DB-25 (D-shaped) connector accessible from the back of the PC The expansion slot provides access to the address bus, data bus, several IRQ lines, clock signal, and several control lines

4. Parallel Port (DB-25 connector)

5. DB-25 Pin Functions Pins 2 through 9 are the 8 data pins D0 through D7. Data Port = “base” address of the printer port(378) Pins 18 through 25 are ground pins Pins 1, 14, 16, and 17 are -strobe, -auto feed, initialize, and -select input. These are all outputs to the printer and accessed via the Control Port whose address is base + 2 Pins 10, 11, 12, 13, and 15 are -acknowledge, busy, paper empty, select, and -error. These are outputs from the printer and accessed via the Status Port whose address is base + 1.

6. Moving data IN and OUT INReads in the data from a peripheral device (I/O) OUTSends data out to a peripheral device(I/O) MOV sends data to and from memory

7. IN and OUT the right way... IN AL, 40HData from port 40h is read into AL OUT 40H, ALData from AL is sent to port 40h IN AL, 340HIllegal because 340 is > FF MOV DX, 378 Data from port 378 is read into AL IN AL, DX OUT DX, ALData from AL sent to port 378

8. Memory Map 00000-003FF1KInterrupt Vectors A0000 - BFFFF128 KVideo RAM B8000-BBFFF16KCGA A0000-AFFFF64KVGA 00400-004FF1/4 KBIOS Data Area F0000 - FFFFF64 KBIOS ROM

9. I / O Map 00 - 1FDMA controller8237A 20 - 21PIC1 (master)8259A 60 - 63Keyboard controller8042 70 - 71Real-time clockMC 146818 80 - 83DMA page register74LS612 1F0-1F8Hard-disk controller 200-207Game adapter 278-27FParallel "printer" port 2 (LPT2) 300-31FPrototype adapter for interfacing 378-37FParallel "printer" port1 (LPT1) 3D0-3DFCGA / VGA controller 3F0-3F7"Floppy" disk controller 3F8-3FFSerial port1 (asynchronous: COM1)