Question

(b) An 8255 IC interfaced with the 8086 microprocessor works as an Input-output port as shown in Figure 1. 8 Data Bus 8 Port-A switches 8 A2 A0 Port-B LEDS A3 A1 U2 AS A6 A7 3 ABC 15 8255 74LS138 Y2 14 A15 6 14 Y410 A14 AO G1 5G2A G2B 9 Y7 XXXX Port-C /4 CS PC\textsubscript{0}-PC\textsubscript{3} 7-segment Display Figure 1: Connection diagram of 8255 IC 1. Find the addresses of ports and control register. (3) II. Find the control word. (2) iii. Find the value of N to load on counter for 100 ms delay if clock frequency is 10 MHz. (5) iv. Write an assembly language program to read 8-bit switch pattern; turn on the LEDs with opposite pattern for 30 secs and then with same pattern for 20 secs; to show the number of ON switches on 7-segment display. (10)

          (b) An 8255 IC interfaced with the 8086 microprocessor works as an Input-output port as shown in
Figure 1.
8
Data Bus
8
Port-A
switches
8
A2
A0
Port-B
LEDS
A3
A1
U2
AS
A6
A7
3
ABC
15
8255
74LS138 Y2
14
A15
6
14
Y410
A14
AO
G1
5G2A
G2B
9
Y7
XXXX
Port-C
/4
CS
PC\textsubscript{0}-PC\textsubscript{3}
7-segment
Display
Figure 1: Connection diagram of 8255 IC
1.
Find the addresses of ports and control register. (3)
II.
Find the control word. (2)
iii.
Find the value of N to load on counter for 100 ms delay if clock frequency is
10 MHz. (5)
iv.
Write an assembly language program to read 8-bit switch pattern; turn on
the LEDs with opposite pattern for 30 secs and then with same pattern for 20
secs; to show the number of ON switches on 7-segment display. (10)

(b) An 8255 IC interfaced with the 8086 microprocessor works as an Input-output port as shown in
Figure 1.
8
Data Bus
8
Port-A
switches
8
A2
A0
Port-B
LEDS
A3
A1
U2
AS
A6
A7
3
ABC
15
8255
74LS138 Y2
14
A15
6
14
Y410
A14
AO
G1
5G2A
G2B
9
Y7
XXXX
Port-C
/4
CS
PC0-PC3
7-segment
Display
Figure 1: Connection diagram of 8255 IC
1.
Find the addresses of ports and control register. (3)
II.
Find the control word. (2)
iii.
Find the value of N to load on counter for 100 ms delay if clock frequency is
10 MHz. (5)
iv.
Write an assembly language program to read 8-bit switch pattern; turn on
the LEDs with opposite pattern for 30 secs and then with same pattern for 20
secs; to show the number of ON switches on 7-segment display. (10)

Added by Guillermo C.

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