FDC37C78 datasheet(67/82 Pages) MICROCHIP

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CR05

This register can only be accessed in

the Configuration Mode and the CSR has been initialized

to 05H. The default value after power up is 00H.

Table 39 - CR05- Floppy Disk Extended Setup Register

BIT NO.

BIT NAME

DESCRIPTION

0,1

Reserved

Read Only. A read returns a 0.

FDC DMA Mode

0=(default) Burst mode is enabled for the FDC FIFO execution

phase data transfers. 1=Non-Burst mode enabled. The FDRQ and

FIRQ pins are strobed once for each byte transferred while the FIFO

is enabled.

4,3

DenSel

Bit 4

Bit 3

Densel output

Normal (Default)

Reserved

Swap Drv 0,1

A high level on this bit, swaps drives and motor sel 0 and 1 of the

FDC. A low level on this bit does not (Default).

EXTx4

External 4 drive support: 0=Internal 2 drive decoder (default).

1=External 4 drive decoder (External 2 to 4 decoder required).

Reserved

Read Only. A read of this bit returns a 0

CR06

This register can only be accessed in the Configuration Mode and after the CSR has been initialized

06H.

The default value of this register after power up is FFH.

This register holds the floppy

disk drive types for up to four floppy disk drives.

CR07

This register can only be accessed in the Configuration Mode and after the CSR has been initialized

to 07H. The default value of this register after power up is 00H. This register holds the value for the auto

power management, polarity of the media ID bits and floppy boot drive information.

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