A
SUBJECT:
ACOE255 – Microprocessors DATE: 14/04/2010 TIME: 100 min
QUESTION 1:
(a) Complete the memory map for connecting 8 8KByte ROM chips to an 8088 system to
form a 64 KByte ROM module starting at physical address:
(20 marks)
i. A0000
ii. C0000
(b) Which of the 8 ROM chips contains the data word located at logical address A010: 3232
when the starting physical address is A0000?
(5 marks)
QUESTION 2:
Demonstrate how a number of 32K X 8 RAM chips can be connected on an 8088 processor
to form a 128K X 8 RAM module.
a. Calculate the number of required chips
(5 marks)
b. Starting at address 80000H, specify the memory map. The RAM should occupy only
one position in the memory map (fully decoded)
(8 marks)
c. Draw all appropriate connections and the decoding circuit using NAND gates(6 marks)
d. Draw all appropriate connections and the decoding circuit using an alternative
implementation method of your choice
(6 marks)
QUESTION 3:
(a) Demonstrate how eight switches and 2 Seven Segment Displays (SSDs) can be connected to a
8088 system using the 82C55 Programmable Peripheral Interface, at addresses 60H, 61H and 62H
respectively. Specify:
i) To which 82C55 port the switches and SSDs will be connected
(5 marks)
ii) The address of the Command Register (CR)
(5 marks)
iii) The circuit diagram
(5 marks)
(b) Write a program in pseudo-code form to keep reading the states of the switches and
display the binary number formed by the switches on the two SSDs in decimal form, provided
it is a two digit decimal number (between 0 and 99), and ER (error) when the number is
greater:
(10 marks)
PROGRAMMING THE 82C55
•
Command byte A
–
–
0 Port C, PC3-PC0 (1-input, 0-output)
1 Port B (1-input, 0-output)
Page 1 of 5
–
–
–
–
–
2 Mode (0-mode 0, 1-mode1)
3 Port C, PC7-PC4 (1-input, 0-output)
4 Port A (1-input, 0-output)
5-6 Mode (00-mode 0, 01-mode 2, 1X-mode 2)
7 Command byte select (always 1 for Command byte A)
QUESTION 4:
(a)
For an even parity system specify:
(i) The parity bit for the following data words.
(4 marks)
(1) 0011001
(2) 0010110
(3) 1011110
(4) 1111011
(ii) Assuming that the rightmost bit in each of the following words is the parity bit,
which transfers were successful and which unsuccessful.
(1)
10111001
(2)
01001010
(3)
11101001
(4 marks)
(4) 10110011
(b) Answer the following questions:
2
B
SUBJECT:
ACOE255 – Microprocessors DATE: 14/04/2010 TIME: 100 min
QUESTION 1:
(a) Complete the memory map for connecting 8 8KByte ROM chips to an 8088 system to
form a 64 KByte ROM module starting at physical address:
(20 marks)
i. 40000
ii. 80000
(b) Which of the 8 ROM chips contains the data word located at logical address 8010: 3232
when the starting physical address is 80000?
(5 marks)
QUESTION 2:
Demonstrate how a number of 32K X 8 RAM chips can be connected on an 8088 processor
to form a 128K X 8 RAM module.
e. Calculate the number of required chips
(5 marks)
f. Starting at address 80000H, specify the memory map. The RAM should occupy only
one position in the memory map (fully decoded)
(8 marks)
g. Draw all appropriate connections and the decoding circuit using NAND gates(6 marks)
h. Draw all appropriate connections and the decoding circuit using an alternative
implementation method of your choice
(6 marks)
QUESTION 3:
(a) Demonstrate how eight switches and 2 Seven Segment Displays (SSDs) can be connected to a
8088 system using the 82C55 Programmable Peripheral Interface, at addresses 60H, 61H and 62H
respectively. Specify:
i) To which 82C55 port the switches and SSDs will be connected
(5 marks)
ii) The address of the Command Register (CR)
(5 marks)
iii) The circuit diagram
(5 marks)
(b) Write a program in pseudo-code form to keep reading the states of the switches and
display the binary number formed by the switches on the two SSDs in decimal form, provided
it is a two digit decimal number (between 0 and 99), and ER (error) when the number is
greater:
(10 marks)
PROGRAMMING THE 82C55
•
Command byte A
–
0 Port C, PC3-PC0 (1-input, 0-output)
3
–
–
–
–
–
–
1 Port B (1-input, 0-output)
2 Mode (0-mode 0, 1-mode1)
3 Port C, PC7-PC4 (1-input, 0-output)
4 Port A (1-input, 0-output)
5-6 Mode (00-mode 0, 01-mode 2, 1X-mode 2)
7 Command byte select (always 1 for Command byte A)
QUESTION 4:
(b)
For an even parity system specify:
(i) The parity bit for the following data words.
(4 marks)
(1) 1010011
(2) 0110111
(3) 1011110
(4) 0100011
(ii) Assuming that the rightmost bit in each of the following words is the parity bit,
which transfers were successful and which unsuccessful.
(1)
00111001
(2)
11001011
(3)
10001101
(4 marks)
(4) 11000010
(b) Answer the following questions:
4