CARD-PCI/GX Hardware Manual
Rev.A
EPSON
15
1.8 Timer counter
SCE8720C has a 8254-equivalent timer counter and 3 independent timers. Their usage
and inputs are shown below:
Table 1.7 Timer 1 settings
Channel 0
GATE 0
Fixed to ON
System timer
CLK IN 0
1.19MHz
CLK OUT 0
Connected to IRQ0 of interrupt controller 1.
Channel 1
GATE 1
Fixed to ON
Refresh request
CLK IN 1
1.19MHz
CLK OUT 1
Refresh request
Channel 2
GATE 2
Controlled by I/O port 61h.
Speaker interface
CLK IN 2
1.19MHz
CLK OUT 2
Used to drive the speaker interface.
