SC2200 NSC [National Semiconductor], SC2200 Datasheet - Page 308

• Manufacturer Part Number: SC2200
• Description: Thin Client On a Chip
• Manufacturer: NSC [National Semiconductor]

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Core Logic Module
I/O Port 042h
Write
Read
I/O Port 043h (R/W)
Notes: 1. If bits [7:6] = 11: Register functions as Read Status Command and:
7:0
5:4
3:1
7:6
5:4
3:1
Bit
7
6
0
0
2. If bits [5:4] = 00: Register functions as Counter Latch Command and:
Description
Counter Value.
Counter Output. State of counter output signal.
Counter Loaded. Indicates if the last count written is loaded.
0: Yes.
1: No.
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.
Current Counter Mode. 0-5.
BCD Mode.
0: Binary.
1: BCD (Binary Coded Decimal).
Counter Select.
00: Counter 0.
01: Counter 1.
10: Counter 2.
11: Read-back command (Note 1).
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.
Current Counter Mode. 0-5.
BCD Mode.
0: Binary.
1: BCD (Binary Coded Decimal).
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
Bits [7:6] = Selects Counter
Bits [3:0] = Don’t care
Table 5-45. Programmable Interval Timer Registers (Continued)
(Continued)
PIT Mode Control Word Register
PIT Timer 2 Counter (Speaker)
PIT Timer 2 Status (Speaker)
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Revision 3.0