TAPE DRIVE REGISTER (TDR)
Address 3F3 READ/WRITE
This register is included for 82077 software
compatability. The robust digital data separator
used in the FDC37C669 does not require its
characteristics modified for tape support. The
contents of this register are not used internal to
Table 4- Tape Select Bits
DRIVE
TAPE SEL1 TAPE SEL2 SELECTED
0
0
1
1
0
1
0
1
None
the device.
software reset.
The TDR is unaffected by a
Bits 2-7 are tri-stated when
1
2
3
read in this mode.
Table 5 - Internal 4 Drive Decode - Normal
DRIVE SELECT OUTPUTS
(ACTIVE LOW)
MOTOR ON OUTPUTS
(ACTIVE LOW)
DIGITAL OUTPUT REGISTER
Bit 7
X
Bit 6
X
Bit 5
X
Bit 4
1
Bit1
0
Bit 0
nDS3
nDS2
nDS1
nDS0 nMTR3 nMTR2 nMTR1 nMTR0
0
1
0
1
X
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
0
1
1
1
1
nBIT 7
nBIT 7
nBIT 7
nBIT 7
nBIT 7
nBIT 6
nBIT 6
nBIT 6
nBIT 6
nBIT 6
nBIT 5
nBIT 5
nBIT 5
nBIT 5
nBIT 5
nBIT 4
nBIT 4
nBIT 4
nBIT 4
nBIT 4
X
X
1
X
0
X
1
X
X
1
1
X
X
X
1
0
0
0
0
X
Table 6 - Internal 4 Drive Decode - Drives 0 and 1 Swapped
DRIVE SELECT OUTPUTS
MOTOR ON OUTPUTS
(ACTIVE LOW)
(ACTIVE LOW)
DIGITAL OUTPUT REGISTER
Bit 7
X
Bit 6
X
Bit 5
X
Bit 4
1
Bit1
0
Bit 0
nDS3
nDS2
nDS1
nDS0
nMTR3 nMTR2 nMTR1
nMTR0
nBIT 5
nBIT 5
nBIT 5
nBIT 5
nBIT 5
0
1
0
1
X
1
1
1
0
1
1
1
0
1
1
0
1
1
1
1
1
0
1
1
1
nBIT 7
nBIT 7
nBIT 7
nBIT 7
nBIT 7
nBIT 6
nBIT 6
nBIT 6
nBIT 6
nBIT 6
nBIT 4
nBIT 4
nBIT 4
nBIT 4
nBIT 4
X
X
1
X
0
X
1
X
X
1
1
X
X
X
1
0
0
0
0
X
24
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