AMD Geode SC2200, Data Book, Page: 300 / 429

312 AMD Geode™ SC2200 Processor Data Book
Core Logic Module - ISA Legacy Register Space 32580B
I/O Port 042h
Write PIT Timer 2 Counter (Speaker)
7:0 Counter Value.
Read PIT Timer 2 Status (Speaker)
7 Counter Output. State of counter output signal.
6 Counter Loaded. Indicates if the last count written is loaded.
0: Yes.
1: No.
5:4 Current Read/Write Mode.
00: Counter latch command.
01: R/W LSB only.
10: R/W MSB only.
11: R/W LSB, followed by MSB.
3:1 Current Counter Mode. 0-5.
0 BCD Mode.
0: Binary.
1: BCD (Binary Coded Decimal).
I/O Port 043h (R/W) PIT Mode Control Word Register
Notes: 1. If bits [7:6] = 11: Register functions as Read Status Command and:
Bit 5 = Latch Count
Bit 4 = Latch Status
Bit 3 = Select Counter 2
Bit 2 = Select Counter 1
Bit 1 = Select Counter 0
Bit 0 = Reserved
2. If bits [5:4] = 00: Register functions as Counter Latch Command and:
Bits [7:6] = Selects Counter
Bits [3:0] = Don’t care
7:6 Counter Select.
00: Counter 0.
01: Counter 1.
10: Counter 2.
11: Read-back command (Note 1).
5:4 Current Read/Write Mode.
00: Counter latch command.
01: R/W LSB only.
10: R/W MSB only.
11: R/W LSB, followed by MSB.
3:1 Current Counter Mode. 0-5.
0 BCD Mode.
0: Binary.
1: BCD (Binary Coded Decimal).
Table 6-45. Programmable Interval Timer Registers (Continued)
Bit Description