CMPE 401 - Computer Interfacing

Assignment #5

1. Briefly explain the similarities and differences among (1) processor-memory busses, (2) input/output peripheral and instrument bussesm, and (3) backplane busses.

2. Briefly explain why modern personal computers have a hierarchy of busses of various types instead of one simple system bus.

3. How do read operations implemented as split transactions help speed up the performance of a microcomputer?

4. Briefly explain how an asynchronous bus attempts to combine the advantages of synchronous busses and asynchronous busses, while avoiding their disadvantages.

5. What are some possible benefits to having the data strobe (DS) and address strobe (AS) signals in the 68000 bus?

6. What is the purpose of the interrupt acknowledge (IACK) in the 68000 bus? How do devices, other than the CPU, know when an IACK cycle is taking place? What should those devices do when they have detected that an IACK cycle has started?

7. What is direct memory access (DMA) and what advantages does it provide in computer interfacing? What are some of the practical complications of DMA?

8. With respect to the 68340 DMA bus protocol, why is there a need for both single-address and two-address DMA bus operations? In which scenarios is each bus operation useful?

9. What is the difference between "burst mode" and "cycle stealing" mode in the 68340 DMA bus protocol? How does a DMA controller request one mode instead of the other?

10. What aspects of the General-Purpose Interface Bus make it especially well suited as an instrument bus? As part of your answer, briefly explain how the 3-way GPIB handshake works.

11. Briefly describe how the initiator ready (IRDY) and target ready (TRDY) signals are used together on the Peripheral Component Interconnct bus to provide semisynchronous data transfers.