FDC37M81 View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
Manufacturer
FDC37M81
SMSC -> Microchip
FDC37M81 Datasheet PDF : 198 Pages
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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. Any future references to
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. The remaining Tape Drive Register
bits TDR.[7:2] are tristated when read. The TDR
is unaffected by a software reset.
Table 4 - Tape Select Bits
TAPE SEL1
TAPE SEL0
DRIVE
(TDR.1)
(TDR.0)
SELECTED
0
0
None
0
1
1
1
0
2
1
1
3
Table 5 - Internal 2 Drive Decode - Normal
DIGITAL OUTPUT
REGISTER
DRIVE SELECT
MOTOR ON OUTPUTS
OUTPUTS (ACTIVE LOW)
(ACTIVE LOW)
Bit 5 Bit 4 Bit1 Bit 0
nDS1
nDS0
nMTR1
nMTR0
X
1
0
0
1
0
nBIT 5
nBIT 4
1
X
0
1
0
1
nBIT 5
nBIT 4
0
0
X
X
1
1
nBIT 5
nBIT 4
Table 6 - Internal 2 Drive Decode - Drives 0 and 1 Swapped
DIGITAL OUTPUT
REGISTER
DRIVE SELECT
MOTOR ON OUTPUTS
OUTPUTS (ACTIVE LOW)
(ACTIVE LOW)
Bit 5 Bit 4 Bit1 Bit 0
nDS1
nDS0
nMTR1
nMTR0
X
1
0
0
0
1
nBIT 4
nBIT 5
1
X
0
1
1
0
nBIT 4
nBIT 5
0
0
X
X
1
1
nBIT 4
nBIT 5
21
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