ELET2100 (EL21C) COURSE TEST #1
WEDNESDAY 19th OCTOBER 2005
MICROPROCESSORS I
Time:
(12:00 - 1:00 )PM
( 1 ) How many bytes of memory does each
instruction (below) occupy:
(a) ANI 3FH
(b) DCX H
(c) JNZ 789AH
(d) LDA 1234H
(e) XRA A [5]
( 2 ) If a CPU has 22-address
pins, what is the last (highest) address that can be
generated
(show decimal or hex value) ? [1]
( 3 ) Describe the effects on
the Flags when the following instructions are executed.
Before each instruction, assuming all Flags
= 0 (reset) and register contents are:
A = 53H; B = 0FH; C = 12H
(i) XRA B
(ii) CPI
45H
(iii)
MVI A, 10H
(iv) DCX B
(v) RAL [5]
( 4 ) If the clock frequency
of the 8085 CPU on your Lab kit is 3.15 MHz, how much
time is required to execute an instruction
of 5 states ? [2]
( 5 ) Figure 1 show two logic
gates fed from signals of an 8085 CPU. Indicate which
output is active when an OUT statement is executed & which is active for an IN
statement. [2]
( 6 ) For Question 5, is the
logic level for active, high
or low ? [1]
( 7 ) If
registers A = 11H, B = 22H, C = 33H, D = 44H, E = 55H, and the SP =
20C2H,
at the start of the program code below, use tables ( or otherwise) to show
the contents
of the Stack area and SP after each instruction:
PUSH D
PUSH B
POP D
What are the contents
of the DE register pair? [4]
( 8 ) Figure 2 shows a (3:8)
address decoder fed with signals from an 8085 CPU.
What two address ranges will cause outputs
X0 and X4 to
be activated,
respectively ? [3]
( 9 ) Write a commented
ends
of Port 00H of your SDK-85 lab kit. Show your initialization code for
the
8755 IC. [3]
( 10 ) What is the function of the PC register in the 8086 CPU ? [1]
( 11 ) What is the maximum Memory and Port space the 8085 CPU can
address ? [2]
( 12 ) What value would you send to the Command Status Register (CSR ie:
Port 20H)
on
the 8155 I/O IC to program all three I/O ports as output ports ? [1]
( 13 ) Write a commented Assembly Language program to count the number
of
set bits in Register B. Your
result should be left in Register E. [5]
Bonus mark:
The SDK-85 kits in the Lab have a small
green Keypad on the lower right of the kit.
How many keys make up the Keypad ?
Maximum mark = 35