1. Graded Quiz #6 Oct. 13, 2017 Clicker [AB]
Covers:
Module 2.c through 2.F

2. Buffer Initialization Code
Memory
Addr
Value
org $500
pin fcb $0
pout fcb $0
org $800
pBuff rmb 5
Given the circular buffer described in class, what is this buffer’s current state based on the values in memory?
(A) Full
(B) Empty
(C) Partially full
(D) This is an invalid state
(E) Not enough information to tell
Given the circular buffer described in class, what is this buffer’s current state based on the values in memory?
(A) Full
(B) Empty
(C) Partially full 
(D) This is an invalid state
(E) Not enough information to tell
500h
02h
501h
00h
‘H’
800h
801h
‘i’
802h
‘3’
803h
‘6’
804h
‘2’

3. Buffer Initialization Code
Memory
Addr
Value
org $500
pin fcb $0
pout fcb $0
org $800
pBuff rmb 5
Given the circular buffer described in class, what is this buffer’s current state based on the state of memory?
(A) Full
(B) Empty
(C) Partially full
(D) This is an invalid state
(E) Not enough information to tell
Given the circular buffer described in class, what is this buffer’s current state based on the state of memory?
(A) Full 
(B) Empty
(C) Partially full
(D) This is an invalid state
(E) Not enough information to tell
500h
04h
501h
00h
‘H’
800h
801h
‘i’
802h
‘3’
803h
‘6’
804h
00h

4. Buffer Initialization Code
Memory
Addr
Value
org $500
pin fcb $0
pout fcb $0
org $800
pBuff rmb 5
Given the circular buffer described in class, what producer/consumer behavior could leave the system in the current memory state?
(A) producer put a total of 4 values on buffer, consumer has done nothing.
(B) producer put a total of 3 values on buffer, consumer has done nothing.
(C) producer has put a total of 8 values on the buffer, consumer has taken a total of 5 off.
(D) Either (A) or (B)
(E) Either (B) or (C)
Given the circular buffer described in class, what producer/consumer behavior could leave the system in the current memory state?
(A) producer put a total of 4 values on buffer, consumer has done nothing.
(B) producer put a total of 3 values on buffer, consumer has done nothing.
(C) producer has put a total of 8 values on the buffer, consumer has taken a total of 5 off.
(D) Either (A) or (B)
(E) Either (B) or (C) 
500h
03h
501h
00h
00h
800h
801h
01h
802h
00h
803h
01h
804h
00h

5. We need an external flip-flop to latch external interrupts because:
(A) You need this for a mask
(B) The device acts as our clock
(C) The interrupt is edge-sensitive and we must hold the flag value
(D) The interrupt is level-sensitive and we must hold the flag value
(E) None of the above
We need an external flip-flop to latch external interrupts because:
(A) You need this for a mask
(B) The device acts as our clock
(C) The interrupt is edge-sensitive and we must hold the flag value
(D) The interrupt is level-sensitive and we must hold the flag value 
(E) None of the above

6. To ignore an externally latched interrupt, the CPU should:
(A) Clear the device flag
(B) Mask the device flag 
(C) Stop clocking the flip-flop
(D) Do either (A) or (B)
(E) None of the above
To ignore an externally latched interrupt, the CPU should:
(A) Clear the device flag
(B) Mask the device flag
(C) Stop clocking the flip-flop
(D) Do either (A) or (B)
(E) None of the above