FDC37C669FR View Datasheet(PDF) - SMSC -> Microchip
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Description
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FDC37C669FR Datasheet PDF : 172 Pages
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Normal Floppy Mode
Normal mode. Register 3F3 contains only
bits 0 and 1. When this register is read, bits 2 -
7 are a high impedance.
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
REG 3F3 Tri-state Tri-state Tri-state Tri-state Tri-state Tri-state tape sel1 tape sel0
Enhanced Floppy Mode 2 (OS2)
Register 3F3 for Enhanced Floppy Mode 2 operation.
DB7
DB6
REG 3F3 Reserved Reserved
DB5
DB4
Drive Type ID
DB3
DB2
DB1
DB0
Floppy Boot Drive tape sel1 tape sel0
For this mode, DRATE0 and DRATE1 pins are
inputs, and these inputs are gated into bits 6
and 7 of the 3F3 register. These two bits are
not affected by a hard or soft reset.
BIT 7 and 6 RESERVED
BIT 5 and 4 DRIVE TYPE ID - These Bits
reflect two of the bits of configuration
register 6.
Which two bits depends on the last drive
selected in the Digital Output Register (3F2).
(See Table 11)
BIT 3 and 2 FLOPPY BOOT DRIVE - These
bits reflect the value of configuration register 7
bits 1, 0. Bit 3 = CR7 Bit DB1. Bit 2 = CR7 Bit
DB0.
BIT 1 and 0 - Tape Drive Select
(READ/WRITE). Same as in Normal and
Enhanced Floppy Mode. 1.
Table 9 - Drive Type ID
DIGITAL OUTPUT REGISTER
REGISTER 3F3 - DRIVE TYPE ID
Bit 1
Bit 0
Bit 5
Bit 4
0
0
CR6 - Bit 1
CR6 - Bit 0
0
1
CR6 - Bit 3
CR6 - Bit 2
1
0
CR6 - Bit 5
CR6 - Bit 4
1
1
CR6 - Bit 7
CR6 - Bit 6
27
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