TMS279X datasheet(39/40 Pages) TI

39 / 40 page

TMS279X (WD279X) FLOPPY DISK FORMATTER / CONTROLLER FAMILY

TABLE 4 - STATUS REGISTER SUMMARY

BIT

ALL TYPE I

COMMANDS

READ

ADDRESS

READ

SECTOR

READ

TRACK

WRITE

SECTOR

WRITE

TRACK

NOT READY

WRITE

PROTECT

WRITE

PROTECT

WRITE

PROTECT

HEAD

LOADED

RECORD

TYPE

SEEK ERROR

RNF

CRC ERROR

TRACK 0

LOST DATA

INDEX PULSE

DRQ

BUSY

status for type I commands

BIT NAME

MEANING

S7 NOT READY

This bit when set indicates the drive is not ready. When reset it indicates that the drive is

ready. This bit is an inverted copy of the ready input and logically 'ORed' with MR.

S6 PROTECTED

When set, indicates write protect is activated. This bit is an inverted copy of WRPT# input.

S5 HEAD LOADED

When set, it indicates the head is loaded and engaged. This bit is a logical "AND" of HLD

and HLT signals.

S4 SEEK ERROR

When set, the desired track was not verified. This bit is reset to 0 when updated.

S3 CRC ERROR

CRC encountered in ID field.

S2 TRACK 00

When set, indicates read/write head is positioned to Track 0. This bit is an inverted copy

of the TR00# input.

S1 INDEX

When set, indicates index mark detected from drive. This bit is an inverted copy of the IP#

input.

S0 BUSY

When set, command is in progress. When reset, no command is in progress.

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