37C67X datasheet(39/194 Pages) SMSC

39 / 194 page

SECTOR SIZE

128 bytes

256 bytes

512 bytes

1024 bytes

...

16 Kbytes

Table 19 - Description of Command Symbols

SYMBOL

NAME

DESCRIPTION

NCN

New Cylinder

Number

The desired cylinder number.

Non-DMA Mode

Flag

When set to 1, indicates that the FDC is to operate in the non-

DMA mode. In this mode, the host is interrupted for each data

transfer.

When set to 0, the FDC operates in DMA mode,

interfacing to a DMA controller by means of the DRQ and nDACK

signals.

Overwrite

The bits D0-D3 of the Perpendicular Mode Command can only be

modified if OW is set to 1. OW id defined in the Lock command.

PCN

Present Cylinder

Number

The current position of the head at the completion of Sense

Interrupt Status command.

POLL

Polling Disable

When set, the internal polling routine is disabled.

When clear,

polling is enabled.

PRETRK

Precompensation

Start Track

Number

Programmable from track 00 to FFH.

Sector Address

The sector number to be read or written. In multi-sector transfers,

this parameter specifies the sector number of the first sector to be

read or written.

RCN

Relative Cylinder

Number

Relative cylinder offset from present cylinder as used by the

Relative Seek command.

Number of

Sectors Per Track

The number of sectors per track to be initialized by the Format

command. The number of sectors per track to be verified during a

Verify command when EC is set.

Skip Flag

When set to 1, sectors containing a deleted data address mark will

automatically be skipped during the execution of Read Data. If

Read Deleted is executed, only sectors with a deleted address

mark will be accessed.

When set to "0", the sector is read or

written the same as the read and write commands.

37C67X Datasheet(PDF) 39 Page - SMSC Corporation

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