19. 0 0 1 P P P P P A0=1
D0
D7 D6 D5 D4 D3 D2 D1
Divide the internal clock by PPPPP to get the basic
internal frequency
2.5 MHz / ? = 100 KHz.
1 1 0 0 1
Clock Command
(Scan Rate Selection)
25D 19h
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20. 3/23/2023 20
Read FIFO Command
(Write)
0 1 0 AI X A A A A0=1
D0
D7 D6 D5 D4 D3 D2 D1
Auto Increment
Select the
desired FIFO
location
21. FIFO Status Register
(Read)
D S/E O U F N N N
D0
D7 D6 D5 D4 D3 D2 D1
Number of
Characters in
FIFO
FIFO Full
Error– Underrun
Error - Overrun
Sensor Closure/Error Flag for
Multiple Closure
Display Unavailable
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A0=0
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MOV DX,5002h ;CW Address
MOV AL,0
OUT DX,AL
MOV AL,39h ;Clock Command
OUT DX,AL
CONT: MOV DX,5002h ;FIFO Status Add.
IN AL,DX
AND AL,07h
JZ CONT
MOV DX,5000h ;Scan Code Buffer
IN AL,DX
MOV SCODE,AL
JMP CONT
25. 1. Draw the address decoder for an 8086
Microprocessor system having a 4x4 keypad
matrix using 8279 controller putting the control
word address = 3006h using:
discrete components.
74138 decoder.
2. Write a program to initialize the controller then
read keypad states and save it continuously in the
memory.
3. Add a PPI with LEDs and a 7-Seg with start
address=5000h, and display the key-N0. on both .
