PC8477B datasheet(14/54 Pages) NSC

14 / 54 page

30 Register Description (Continued)

Head Select

Indicates the active high status of

the HDSEL pin at the end of the Execution

Phase

D1 – D0

Drive Select 10

These two binary encoded

bits indicate the logical drive selected at the end

of the Execution Phase

00 e Drive 0 selected

01 e Drive 1 selected

10 e Drive 2 selected

11 e Drive 3 selected

3102 Status Register 1 (ST1)

DESC

RESET

COND

End of Track

Controller transferred the last

byte of the last sector without the TC pin be-

coming active The last sector is the End of

Track sector number programmed in the Com-

mand Phase

Not Used Always 0

CRC Error

If this bit is set and bit 5 of ST2 is

clear then there was a CRC error in the Ad-

dress Field of the correct sector If bit 5 of ST2

is also set then there was a CRC error in the

Data Field

Overrun

Controller was not serviced by the mP

soon enough during a data transfer in the Exe-

cution Phase For read operations indicates a

data overrun For write operations indicates a

data underrun

Not Used Always 0

No Data

Three possible problems

1 Controller cannot find the sector specified in

the Command Phase during the execution of

a Read Write Scan or Verify command An

address mark was found however so it is not

a blank disk

2 Controller cannot read any Address Fields

without a CRC error during a Read ID com-

mand

3 Controller cannot find starting sector during

execution of Read A Track command

Not Writable

Write Protect pin is active when a

Write or Format command is issued

Missing Address Mark

If bit 0 of ST2 is clear

then the controller cannot detect any Address

Field Address Mark after two disk revolutions If

bit 0 of ST2 is set then the controller cannot

detect the Data Field Address Mark after finding

the correct Address Field

3103 Status Register 2 (ST2)

DESC

SEH

SNS

RESET

COND

Not Used Always 0

Control Mark

Controller tried to read a sector

which contained a deleted data address mark

during execution of Read Data or Scan com-

mands Or if a Read Deleted Data command

was executed a regular address mark was de-

tected

CRC Error in Data Field

Controller detected a

CRC error in the Data Field Bit 5 of ST1 is also

set

Wrong Track

Only set if desired sector is not

found and the track number recorded on any

sector of the current track is different from the

track address specified in the Command Phase

Scan Equal Hit

‘‘Equal’’ condition satisfied dur-

ing any Scan command

Scan Not Satisfied

Controller cannot find a

sector on the track which meets the desired

condition during any Scan command

Bad Track

Only set if the desired sector is not

found the track number recorded on any sector

on the track is FF (hex) indicating a hard error in

IBM format and is different from the track ad-

dress specified in the Command Phase

Missing Address Mark in Data Field

Control-

ler cannot find the Data Field AM during a Read

Scan or Verify command Bit 0 of ST1 is also

set

3104 Status Register 3 (ST3)

DESC

TK0

HDS

DS1

DS0

RESET

101

COND

Not Used Always 0

Write Protect

Indicates active high status of

the WP pin

Not Used Always 1

Track 0

Indicates active high status of the

TRK0 pin

Not Used Always 1

Head Select

Indicates the active high status of

the HD bit in the Command Phase

D1 – D0

Drive Select 10

These two binary encoded

bits indicate the DS1 – DS0 bits in the Command

Phase

PC8477B датащи(PDF) 14 Page - National Semiconductor (TI)

PC8477B датащи(HTML) 14 Page - National Semiconductor (TI)

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

датащи скачать

ссылки URL