FDC37M81 SMSC [SMSC Corporation], FDC37M81 Datasheet - Page 21

• Manufacturer Part Number: FDC37M81
• Description: PC98/99 Compliant Enhanced Super I/O Controller with Keyboard/Mouse Wake-Up
• Manufacturer: SMSC [SMSC Corporation]

TAPE DRIVE REGISTER (TDR)
Address 3F3 READ/WRITE
The Tape Drive Register (TDR) is included for
82077 software compatibility and allows the
user to assign tape support to a particular drive
during initialization.
Bit 5
Bit 5
X
X
1
0
1
0
DIGITAL OUTPUT
DIGITAL OUTPUT
Bit 4
Bit 4
REGISTER
REGISTER
X
X
1
0
1
0
Table 6 - Internal 2 Drive Decode - Drives 0 and 1 Swapped
Any future references to
Bit1
Bit1
X
X
TAPE SEL1
0
0
0
0
(TDR.1)
Table 5 - Internal 2 Drive Decode - Normal
0
0
1
1
Bit 0
Bit 0
X
X
0
1
0
1
Table 4 - Tape Select Bits
OUTPUTS (ACTIVE LOW)
OUTPUTS (ACTIVE LOW)
nDS1
nDS1
DRIVE SELECT
DRIVE SELECT
1
0
1
0
1
1
TAPE SEL0
(TDR.0)
21
0
1
0
1
that drive automatically invokes tape support.
The TDR Tape Select bits TDR.[1:0] determine
the tape drive number. Table 4 illustrates the
Tape Select Bit encoding. Note that drive 0 is
the boot device and cannot be assigned tape
support.
bits TDR.[7:2] are tristated when read. The TDR
is unaffected by a software reset.
nDS0
nDS0
0
1
1
1
0
1
The remaining Tape Drive Register
SELECTED
DRIVE
MOTOR ON OUTPUTS
MOTOR ON OUTPUTS
None
nMTR1
nMTR1
nBIT 5
nBIT 5
nBIT 5
nBIT 4
nBIT 4
nBIT 4
1
2
3
(ACTIVE LOW)
(ACTIVE LOW)
nMTR0
nMTR0
nBIT 4
nBIT 4
nBIT 4
nBIT 5
nBIT 5
nBIT 5