82C55A
INTERRUPT
REQUEST
PC3 PA0
PA1
R0
R1
PA2
PA3
PA4
R2
R3
R4
FULLY
DECODED
KEYBOARD
INTERRUPT
REQUEST
PA5
PA6
PA7
R5
SHIFT
CONTROL
PC3 PA0
PA1
R0
R1
R2
MODE 1
(INPUT)
PA2
FULLY
DECODED
KEYBOARD
PA3
PA4
R3
R4
PC4
PC5
STROBE
ACK
PA5
PA6
PA7
R5
SHIFT
CONTROL
MODE 1
(INPUT)
82C55A
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
B0
B1
B2
B3
B4
B5
PC4
PC5
PC6
PC7
STROBE
ACK
BUST LT
TEST LT
82C55A
BURROUGHS
SELF-SCAN
DISPLAY
MODE 1
(OUTPUT)
TERMINAL
ADDRESS
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
BACKSPACE
CLEAR
MODE 0
(INPUT)
PC1
PC2
PC6
PC7
DATA READY
ACK
BLANKING
CANCEL WORD
INTERRUPT
REQUEST
FIGURE 20. KEYBOARD AND TERMINAL ADDRESS
INTERFACE
FIGURE 19. KEYBOARD AND DISPLAY INTERFACE
INTERRUPT
REQUEST
LSB
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PC4
PC5
PC6
PC7
PC3 PA0
PA1
R0
R1
R2
R3
R4
R5
SHIFT
CONTROL
PA2
PA3
PA4
CRT CONTROLLER
• CHARACTER GEN.
• REFRESH BUFFER
• CURSOR CONTROL
12-BIT
A/D
PA5
PA6
PA7
MODE 0
(OUTPUT)
CONVERTER
(DAC)
MODE 1
(OUTPUT)
ANALOG
OUTPUT
PC7
PC6
PC5
PC4
DATA READY
ACK
BLANKED
82C55A
BLACK/WHITE
PC0
PC1
82C55A
STB DATA
BIT
SET/RESET
PC2
PC1
PC0
ROW STB
COLUMN STB
CURSOR H/V STB
PC2
PC3
SAMPLE EN
STB
PB0
PB1
PB2
LSB
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
8-BIT
MODE 0
(OUTPUT)
ANALOG
INPUT
D/A
CONVERTER
(ADC)
PB3
CURSOR/ROW/COLUMN
ADDRESS
H&V
MODE 0
(INPUT)
PC4
PC5
PC6
PC7
MAB
FIGURE 21. DIGITAL TO ANALOG, ANALOG TO DIGITAL
FIGURE 22. BASIC CRT CONTROLLER INTERFACE
15
HARRIS [ HARRIS CORPORATION ]
