BLUE CHIP AOP-12D, User Manual, Page: 21 / 49

Operation of The Card Page 15
Blue Chip Technology Ltd. 01270146.doc Page 15
Block Diagram of
Timer Connections
The timer circuit appears to the PC as four ports. These four ports are mapped
into the AOP-12d address map as follows:
BASE
+ 8
Timer/Counter 0 (read/write).
+ 9 Timer/Counter 1 (read/write).
+ 10 Timer/Counter 2 (read/write).
+ 11 Control register, (write only).
Bits 6 and 7 in the control register enable and disable Timer 0 and 1, and
Timer 2.
Timer 2
1 MHz
Clock
Timer 0
Timer 2 Output
Connection
Timer 0 Output
Connection
DMA Transfer
Control Circuit
Timer 1