Specifications

EPC-5A Hardware & Software Reference Manual
AA
Page A-2
Counter-Timer functions:
R400 emulating 8254 of PC/AT
I/O Addr Functional group Usage
040 Timer Counter 0
041 Counter 1
042 Counter 2
043 Control (W)
Keyboard Port:
Intel 8242 emulating 8742 of PC/AT
I/O Addr Functional group Usage
060 Keyboard controller Data I/O register
061 NMI status NMI status
064 Keyboard controller Command/status register
Time-of-Day Clock:
R400 emulating MC6818 of PC/AT
I/O Addr Functional group Usage
070 Real-time clock RTC index reg / NMI enable
071 RTC data register
0 seconds
1 seconds alarm
2 minutes
3 minutes alarm
4 hours
5 hours alarm
6 day of week
7 date of month
8 month
9 year
A status A
B status B
C status C
D status D
E RAM
...
3F RAM
DMA Page Registers:
R400 emulating 74LS612 of PC/AT
I/O Addr Functional group Usage
081 DMA Channel 2 page register
082 Channel 3 page register
083 Channel 1 page register
087 Channel 0 page register
089 Channel 6 page register
08A Channel 7 page register
08B Channel 5 page register
08F Refresh page register