Quiz 18.5

DIRECTIONS: Read each question carefully. Then click on the dot next to the answer that most closely fits the question. Try to answer all questions on this quiz and when you are done, click on the grade me button at the bottom.

Coverage: Section 18.7

  1. What are some benefits to memory mapped I/O?
there is an unlimited supply of port numbers
does not require explicit IN and OUT instructions
treats I/O like memory so it is more uniform and easier to understand
all of the above

  1. Which chip lacks explicit I/O instructions?
Intel 80486
Motorola 68000

  1. What do we call I/O that utilizes explicit I/O instructions?
isolated
memory mapped
homogeneous
multiplexed

  1. Which kinds of logic circuits are used to alert devices that the address on the bus applies to it?
multiplexor
encoder
decoder

  1. If 8 words of memory were allocated to an I/O device, what size of decoder would be needed?
8×3
3×8
2×4

  1. The following logic diagram shows how the device active wire would be set high for a device whose 8 memory words go from address ... to ...
GIFs/decoder.gif
00000000 to 00000111
11110000 to 10001111
00001000 to 00001111
10001111 to 11111111

  1. Which instructions move data from the processor out to the peripheral in a memory-mapped I/O system?
IN
OUT
LOAD
STORE

  1. In the following program, which instructions check to see if the data ready bit is turned on? 
     1.   CHECKCTL: LOD  1000
     2.             SUB  "01"b
     3.             JNZ  CHECKCTL
     4.             LOD  1001
     5.             STD  X
     6.             LDI  "11"b
     7.             STD  1000
     8.             JMP  CHECKCTL
1-3
6-8
4-5

  1. In the program in the question above, which instructions tell the peripheral that it received the data byte and the peripheral should continue on to the next byte?
1-2
4-5
6-7
8 -