7. Function Description
F81865
7.1. Power on Strapping Option
The F81865 provides six pins for power on hardware strapping to select required functions. See
below table for the detail:
Pin No.
4
123
7
124
126
5
Symbol
FWH_TRAP
PWM_Duty
SPI_TRAP
I2C_ADDR
Config4E_2E
PWM_DC
7.2. FDC
Value
1
0
1
0
1
0
1
0
1
0
1
0
Description
FWH as a primary BIOS
SPI as a primary BIOS
Power on fan speed default duty is 60%. ( Default)
Power on fan speed default duty is 100%.
SPI function disable(Default)
SPI function enable
The I2C slave address is 8’h5C (Default)
The I2C slave address is 8’h5A
Configuration Register I/O port is 4E/4F. (Default)
Configuration Register I/O port is 2E/2F.
Fan control mode: PWM mode. ( Default)
Fan control mode: DAC mode.
The Floppy Disk Controller provides the interface between a host processor and one floppy disk
drive. It integrates a controller and a digital data separator with write pre-compensation, data rate
selection logic, microprocessor interface, and a set of registers. The FDC supports data transfer rates
of 250 Kbps, 300 Kbps, 500 Kbps, 1 Mbps and 2 Mbps. It operates in PC/AT mode.
The FDC configuration is handled by software and a set of Configuration registers. Status, Data,
and Control registers facilitate the interface between the host microprocessor and the disk drive,
providing information about the condition and/or state of the FDC. These configuration registers can
select the data rate, enable interrupts, drives, and DMA modes, and indicate errors in the data or
operation of the FDC/FDD. The controller manages data transfers using a set of data transfer and
control commands. These commands are handled in three phases: Command, Execution, and
Result. Not all commands utilize all these three phases.
The below content is about the FDC device register descriptions. All the registers are for
software porting reference.
Status Register A (PS/2 mode) ⎯ Base + 0
Bit
Name
R/W Default
Description
7
INTPEND
R
0 This bit indicates the state of the interrupt output.
0: a second drive has been installed.
6
DRV2_N
R
-
1: a second drive has not been installed.
20
May, 2010
V0.28P