PC87332 datasheet(35/98 Pages) NSC

35 / 98 page

40 FDC Command Set Description (Continued)

The sixth byte of the result phase varies depending on what

commands have been previously executed If a format com-

mand has previously been issued and no reads or writes

have been issued since then this byte contains the Sectors

per track value If a read or a write command has been

executed more recently than a format command this byte

contains the End of Track value The LOCK bit is set in the

Lock command The eighth result byte also contains the bits

programmed in the Perpendicular Mode command The last

two bytes of the Dumpreg Result Phase are set in the Con-

figure command After a hardware or software reset the

parameters in the result bytes are set to their appropriate

default values

Note

Some of these parameters are unaffected by a software reset de-

pending on the state of the LOCK bit See the Lock Command for

further information

Command Phase

00001110

Execution Phase

Internal registers read

Result Phase

PTR Drive 0

PTR Drive 1

PTR Drive 2

PTR Drive 3

Step Rate Time

Motor Off Time

Motor On Time

DMA

Sector per TrackEnd of Track (Note)

LOCK

DC3

DC2

DC1

DC0

GAP

EIS

FIFO

POLL

THRESH

PRETRK

Note

Sectors per Track parameter returned if last command issued was

Format End of Track parameter returned if last command issued was

Read or Write

413 Format Track Command

This command formats one track on the disk in IBM ISO or

Perpendicular format After the index hole is detected data

patterns are written on the disk including all gaps Address

Marks Address Fields and Data Fields The exact format is

determined by the following parameters

1 The MFM bit in the Opcode (first command) byte which

determines the format of the Address Marks and the en-

coding scheme

2 The IAF bit in the Mode command which selects be-

tween IBM and ISO format

3 The WGATE and GAP bits in the Perpendicular Mode

command which select between the conventional and

Toshiba Perpendicular format

4 The Bytes per Sector code which determines the sector

size

5 The Sector per Track parameter which determines how

many sectors are formatted on the track

6 The Data Pattern byte which is used as the filler byte in

the Data Field of each sector

Command Phase

MFM

XXXHDDR1

DR0

Bytes per Sector

Sectors per Track

Format Gap

Data Pattern

Execution Phase

System transfers four ID bytes (track

head sector bytessector) per sector to the floppy control-

ler via DMA or Non-DMA modes The entire track is format-

ted The data block in the Data Field of each sector is filled

with the data pattern byte

Result Phase

Status Register 0

Status Register 1

Status Register 2

Undefined

To allow for flexible formatting the mP must supply the four

Address Field bytes (track head sector bytes per sector

code) for each sector formatted during the Execution

Phase This allows for non-sequential sector interleaving

This transfer of bytes from the mP to the controller can be

done in the DMA or Non-DMA mode with the FIFO enabled

or disabled

The Format Gap byte in the Command Phase is dependent

on the data rate and type of disk drive and controls the

length of GAP3 Some typical values for the programmable

GAP3 are given in Table 4-1

Figure 4-2 shows the track

format for each of the formats recognized by the format

command Table 4-2 shows some typical values for the For-

mat GAP3 based on media type The Format command ter-

minates when the index hole is detected a second time at

which point an interrupt is generated Only the first three

status bytes in the Result Phase are significant

PC87332 датащи(PDF) 35 Page - National Semiconductor (TI)

PC87332 датащи(HTML) 35 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 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98

датащи скачать

ссылки URL