DIGITAL-LOGIC AG
PCCP5 Manual V2.3
45
I/O Ad-
dress
Read/Write
Status
Description
0021h
R / W
PIC master interrupt mask register (OCW1)
bit 7
= 0
Enable parallel printer interrupt
bit 6
= 0
Enable diskette interrupt
bit 5
= 0
Enable hard dis k interrupt
bit 4
= 0
Enable serial port 1 interrupt
bit 3
= 0
Enable serial port 2 interrupt
bit 2
= 0
Enable video interrupt
bit 1
= 0
Enable kybd/pointing device/RTC inter-
rupt
bit 0
= 0
Enable interrupt timer
0021h
W
PIC OWC2 (if bits 4-3 = 0)
bit 7
= Reserved
bits 6-5 = 000
Rotate in automatic EOI mode (clear)
001
Nonspecific EOI
010
No operation
011
Specific EOI
100
Rotate in automatic EOI mode (set)
101
Rotate on nonspecific EOI command
110
Set priority command
111
Rotate on specific EOI command
bits 4-3 = Reserved (should be 00)
bits 2-0 = Interrupt request to which the command
applies
0020h
R
PIC interrupt request and in-service registers programmed
by OCW3
Interrupt request register
bits 7-0 = 0
No active request for the corres ponding
interrupt line
1
Active request for the corresponding
interrupt line
Interrupt in-service register
bits 7-0 = 0
Corresponding interrupt line not cur-
rently
being serviced
1
Corresponding interrupt line is currently
being serviced
0021h
W
PIC OCW3 (if bit 4 = 0, bit 3 = 1)
bit 7
= Reserved (should 0)
bits 6-5 = 00
No operation
01
No operation
10
Reset special mask
11
Set special mask
bit 4
= Reserved (should be 0)
bit
= Reserved (should be 1)
bit 2
= 0
No poll command
1
Poll command
bits 1-0 = 00
No operation
01
Operation
10
Read interrupt request register on next
read at port 0020 h
11
Read interrupt in-service register on
next read at port
0020h
Continued...
