FDC37N769_07 SMSC [SMSC Corporation], FDC37N769_07 Datasheet - Page 22

• Manufacturer Part Number: FDC37N769_07
• Description: 3.3V Super I/O Controller with Infrared Support for Portable Applications
• Manufacturer: SMSC [SMSC Corporation]

TAPE DRIVE REGISTER (TDR)
The Tape Drive register (Base Address + 3) is included for 82077 software compatibility and allows the user to assign
tape support to a particular drive during initialization. Any future reference to that drive automatically invokes tape
support. The Tape Select bits TDR.[1:0] determine the tape drive number. Table 15 illustrates the Tape Select bit
encoding. Note that drive 0 is the boot device and cannot be assigned tape support.
The encoding of the TDR depends on the Floppy mode (see section Floppy Modes on page 16). The TDR is
unaffected by a software reset.
Normal Floppy Mode
In Normal mode the TDR contains only bits 0 and 1 (Table 16). During a read in Normal mode TDR bits 2 - 7 are high
impedance. The Tape Select Bits are Read/Write.
Enhanced Floppy Mode 2 (OS2)
The configuration of the TDR in the Enhanced Floppy Mode 2 (OS/2 mode) is shown in Table 17.
Reserved, Bits 6 - 7
Bits 6 and 7 are RESERVED. Reserved bits cannot be written and return 0 when read.
SMSC DS – FDC37N769
Bit 7
X
X
X
X
X
X
1
0
TDR
TDR
Bit 6
Tri-state
DB7
X
X
X
X
1
X
X
0
DIGITAL OUTPUT REGISTER
DB7
Table 14 - External 2-to-4 Drive Decode: Drives 0 and 1 Swapped
Reserved
Bit 5
Tri-state
X
1
X
X
X
0
X
X
DB6
DB6
TAPE SEL1
(TDR.1)
Table 17 - TDR Enhanced Floppy Mode 2
Table 16 - TDR Normal Floppy Mode
0
0
1
1
Bit 4
Tri-state
X
X
X
X
X
X
1
0
DATASHEET
DB5
Drive Type ID
DB5
Table 15 - Tape Select Bits
Bit1
TAPE SEL0
Tri-state
Page 22 of 137
0
0
1
1
0
0
1
1
DB4
DB4
(TDR.0)
0
1
0
1
Bit 0
Tri-state
0
1
0
1
0
1
0
1
Floppy Boot Drive
DB3
DB3
SELECTED
DRIVE SELECT
nDS1
(ACTIVE LOW)
DRIVE
NONE
Tri-state
0
0
1
1
0
0
1
1
OUTPUTS
DB2
DB2
1
2
3
nDS0
1
0
0
1
1
0
0
1
Tape
Sel1
DB1
Tape
DB1
Sel1
nMTR1
(ACTIVE LOW)
MOTOR ON
1
1
1
1
1
1
1
1
OUTPUTS
Tape
DB0
Sel0
Tape
DB0
Sel0
nMTR0
0
0
0
0
1
1
1
1
Rev. 02-16-07