SC2200 NSC [National Semiconductor], SC2200 Datasheet - Page 219

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

Revision 3.0
Core Logic Module
Table 5-29. F0: PCI Header and Bridge Configuration Registers for GPIO and LPC Support (Continued)
Index 8Ah
Index 8Bh
7:0
1:0
Bit
1
0
7
6
5
4
3
2
Description
Re-trigger General Purpose Timer 1 on Floppy Disk Activity.
0: Disable.
1: Enable.
Any access to the floppy disk drive address ranges listed below reloads General Purpose Timer 1:
The active floppy disk drive is configured via F0 Index 93h[7].
Re-trigger General Purpose Timer 1 on Primary Hard Disk Activity.
0: Disable.
1: Enable.
Any access to the primary hard disk address range selected in F0 Index 93h[5], reloads General Purpose Timer 1.
GPT2_COUNT. This field represents the load value for General Purpose Timer 2. This value can represent either an 8-bit or
16-bit counter (configured in F0 Index 8Bh[5]). It is loaded into the counter when the timer is enabled (F0 Index 83h[1] = 1).
Once the timer is enabled and a transition occurs on GPIO7, the timer is re-loaded.
The counter is decremented with each clock of the configured timebase (1 msec or 1 sec selected at F0 Index 8Bh[3]). Upon
expiration of the counter, an SMI is generated and the top level of status is F1BAR0+I/O Offset 00h/02h[9]. The second level
of status is reported at F1BAR0+I/O Offset 04h/06h[1]). Once expired, this counter must be re-initialized by either disabling
and enabling it, or by writing a new count value in this register.
For GPIO7 to act as the reload for this counter, it must be enabled as such (F0 Index 8Bh[2]) and be configured as an input.
(GPIO pin programming is at F0BAR0+I/O Offset 20h and 24h.)
Re-trigger General Purpose Timer 1 (GP Timer 1) on Secondary Hard Disk Activity.
0: Disable.
1: Enable.
Any access to the secondary hard disk address range selected in F0 Index 93h[4] reloads GP Timer 1.
VGA Timer Base. Selects timebase for VGA Timer Register (F0 Index 8Eh).
0: 1 millisecond.
1: 32 microseconds.
General Purpose Timer 2 (GP Timer 2) Shift. GP Timer 2 is treated as an 8-bit or 16-bit timer.
0: 8-bit. The count value is loaded into GP Timer 2 Count Register (F0 Index 8Ah).
1: 16-bit. The value loaded into GP Timer 2 Count Register is shifted left by eight bits, the lower eight bits become zero,
General Purpose Timer 1 (GP Timer 1) Shift. GP Timer 1 is treated as an 8-bit or 16-bit timer.
0: 8-bit. The count value is that loaded into GP Timer 1 Count Register (F0 Index 88h).
1: 16-bit. The value loaded into GP Timer 1 Count Register is shifted left by eight bit, the lower eight bits become zero, and
General Purpose Timer 2 (GP Timer 2) Timebase. Selects timebase for GP Timer 2 (F0 Index 8Ah).
0: 1 second.
1: 1 millisecond.
Re-trigger Timer on GPIO7 Pin Transition. A rising-edge transition on the GPIO7 pin reloads GP Timer 2 (F0 Index 8Ah).
0: Disable.
1: Enable.
For GPIO7 to work here, it must first be configured as an input. (GPIO pin programming is at F0BAR0+I/O Offset 20h and
24h.)
Reserved. Set to 0.
— Primary floppy disk: I/O Port 3F2h-3F5h, 3F7h
— Secondary floppy disk: I/O Port 372h-375h, 377h
and this 16-bit value is used as the count for GP Timer 2.
this 16-bit value is used as the count for GP Timer 1.
(Continued)
General Purpose Timer 2 Control Register (R/W)
General Purpose Timer 2 Count Register (R/W)
219
Reset Value: 00h
Reset Value: 00h
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