W83977EG-AW Datasheet, PDF(34/142 Page) Nuvotem Talema – These products are not designed for use in life support appliances

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W83977EG-AW Datasheet, PDF (34/142 Pages) Nuvotem Talema – These products are not designed for use in life support appliances

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W83977EF-AW/W83977EG-AW

(20) Invalid

PHASE R/W

Command W

Result

D7 D6 D5 D4 D3 D2 D1 D0

------------- Invalid Codes -----------------

-------------------- ST0 ----------------------

REMARKS

Invalid codes (no operation-

FDC goes to standby state)

ST0 = 80H

5.2 Register Descriptions

There are several status, data, and control registers in W83977EF. These registers are defined below:

ADDRESS

OFFSET

base address + 0

base address + 1

base address + 2

base address + 3

base address + 4

base address + 5

base address + 7

READ

WRITE

SA REGISTER

SB REGISTER

DO REGISTER

TD REGISTER

MS REGISTER

DR REGISTER

DT (FIFO) REGISTER

DI REGISTER

CC REGISTER

5.2.1 Status Register A (SA Register) (Read base address + 0)

This register is used to monitor several disk interface pins in PS/2 and Model 30 modes. In PS/2 mode,

the bit definitions for this register are as follows:

7 6 5 4 3 21 0

DIR

WP#

INDEX#

HEAD

TRAK0#

STEP

DRV2#

INIT PENDING

INIT PENDING (Bit 7):

This bit indicates the value of the floppy disk interrupt output.

DRV2# (Bit 6):

0 A second drive has been installed

1 A second drive has not been installed

STEP (Bit 5):

This bit indicates the complement of STEP# output.

-32-

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