MC 542 Organizao de Computadores Teoria e Prtica

MC 542 Organização de Computadores Teoria e Prática 2007 Prof. Paulo Cesar Centoducatte@ic. unicamp. br www. ic. unicamp. br/~ducatte MC 542 8. 1

MC 542 Arquitetura de Computadores Input / Output “DDCA” - (Capítulo 8) MC 542 8. 2

Título do Capítulo Abordado Sumário MC 542 8. 3

Input / output • I/O Mapeado em Memória • I/O Mapedado em Espaçamento de Endereço Próprio MC 542 8. 4

I/O Mapeado em Memória • O Processador acessa os dispositivos de I/O (keyboards, monitores, printers) da mesma forma que acessa à Memória • A cada dispositivo de I/O é atribuído um ou mais endereços • Quando o endereço é utilizado o daddo é lido ou escrito no dispositivo de I/O no lugar da memória • Em geral, uma parte do espaço de endereçamento é dedicado aos dispositivos de I/O (por exemplo, endereços de 0 x. FFFF 0000 a 0 x. FFFF) MC 542 8. 5

Memory-Mapped I/O Hardware • Address Decoder: – Looks at address to determine which device/memory communicates with the processor • I/O Registers: – Hold values written to the I/O devices • Read. Data Multiplexer: – Selects between memory and I/O devices as source of data sent to the processor MC 542 8. 6

The Memory Interface MC 542 8. 7

Memory-Mapped I/O Hardware MC 542 8. 8

Memory-Mapped I/O Code • Suppose I/O Device 1 is assigned the address 0 x. FFFFFFF 4 – Write the value 42 to I/O Device 1 – Read the value from I/O Device 1 and place it in $t 3 MC 542 8. 9

Memory-Mapped I/O Code • Write the value 42 to I/O Device 1 (0 x. FFFFFFF 4) addi $t 0, $0, 42 sw $t 0, 0 x. FFF 4($0) Recall that the 16 bit immediate is sign-extended to 0 x. FFFFFFF 4 MC 542 8. 10

Memory-Mapped I/O Code • Read the value from I/O Device 1 and place it in $t 3 sw $t 3, 0 x. FFF 4($0) MC 542 8. 11

Example I/O Device: Speech Chip • Allophone: fundamental unit of sound, for example: – “hello” = HH 1 EH LL AX OW • Each allophone assigned a 6 -bit code, for example: – “hello” = 0 x 1 B 0 x 07 0 x 2 D 0 x 0 F 0 x 20 See www. speechchips. com MC 542 8. 12

Speech Chip I/O • A 6: 1: allophone input • ALD: allophone load (low-asserted, i. e. loads the address when ALD goes low) • SBY: standby, indicates when the speech chip is standing by waiting for the next allophone MC 542 8. 13

Driving the Speech Chip 1. Set ALD to 1 2. Wait until the chip asserts SBY to indicate that it has finished speaking the previous allophone and is ready for the next one 3. Write a 6 -bit allophone to A 6: 1 4. Reset ALD to 0 to initiate speech MC 542 8. 14

Memory-Mapping the I/O Ports • A 6: 1: 0 x. FFFFFF 00 • ALD: 0 x. FFFFFF 04 • SBY: 0 x. FFFFFF 08 MC 542 8. 15

Software Driver for the Speech Chip init: addi lui addi start: sw loop: lw beq add lw sw sw addi beq j $t 1, $t 2, $t 3, $t 4, $0, 1 $0, 20 0 x 1000 $0, 0 # # $t 1 $t 2 $t 3 $t 4 = = 1 array size * 4 array base address 0 (array index) $t 1, 0 x. FF 04($0) $t 5, 0 x. FF 08($0) $0, $t 5, loop # ALD = 1 # $t 5 = SBY # loop until SBY == 1 $t 5, $t 3, $t 4 $t 5, 0($t 5) $t 5, 0 x. FF 00($0) $0, 0 x. FF 04($0) $t 4, 4 $t 4, $t 2, done start # # # # $t 5 = address of allophone $t 5 = allophone A 6: 1 = allophone ALD = 0 to initiate speech increment array index last allophone in array? repeat done: MC 542 8. 16

Hardware for Supporting SP 0256 MC 542 8. 17

SPO 256 Pin Connections MC 542 8. 18

Summary • You have learned about: – Combinational and sequential logic – Schematic and HDL design entry – Digital building blocks: adders, ALUs, multiplexers, decoders, memories – Assembly language – computer architecture – Processor design – microarchitecture • The world is an increasingly digital place • You have the tools to design and build powerful digital circuits that will shape our world • Use this power wisely and for good! MC 542 8. 19