RESET
N/A
1
1
0
0
0
1
1
CONDITION
nDRIVE SELECT 2, Bit 0
Active low status of the DS2 disk interface output.
nDRIVE SELECT 3, Bit 1
Active low status of the DS3 disk interface output.
Write Gate, Bit 2
Active high status of the latched WGATE output signal. This bit is latched by the active going edge of WGATE and is
cleared by the read of the DIR register.
Read Data, Bit 3
Active high status of the latched RDATA output signal. This bit is latched by the inactive going edge of RDATA and is
cleared by the read of the DIR register.
Write Data, Bit 4
Active high status of the latched WDATA output signal. This bit is latched by the inactive going edge of WDATA and
is cleared by the read of the DIR register. This bit is not gated with WGATE.
nDRIVE SELECT 0, Bit 5
Active low status of the DS0 disk interface output.
nDRIVE SELECT 1, Bit 6
Active low status of the DS1 disk interface output.
nDRV2, Bit 7
Active low status of the DRV2 disk interface input.
DIGITAL OUTPUT REGISTER (DOR)
The Digital Output register (Base Address + 2) controls the drive select and motor enables of the disk interface
outputs (Table 9 and Table 10). The DOR also contains the DMA logic enable and a software reset bit. The DOR is
read/write and unaffected by a software reset.
Table 9 - Digital Output Register
7
6
5
4
3
2
1
0
MOT EN3 MOT EN2 MOT EN1 MOT EN0 DMAEN nRESET DRIVE
DRIVE
SEL1
SEL0
RESET
0
0
0
0
0
0
0
0
CONDITION
DOR Bit Descriptions
DRIVE SELECT, Bits 0 - 1
These two bits are binary encoded for the four drive selects DS0-DS3, thereby allowing only one drive to be selected
at one time.
nRESET, Bit 2
A logic “0” written to this bit resets the Floppy disk controller. This reset will remain active until a logic “1” is written to
this bit. This software reset does not affect the DSR and CCR registers, nor does it affect the other bits of the DOR
register. The minimum reset duration required is 100ns, therefore toggling this bit by consecutive writes to this
register is a valid method of issuing a software reset.
SMSC DS – FDC37N769
Page 20 of 137
Rev. 12/21/2000
SMSC [ SMSC CORPORATION ]
