PC87309VLJ datasheet(50/192 Pages) NSC

50 / 192 page

The Floppy Disk Controller (FDC) (Logical Device 0)

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Bit 2 - Scan Not Satisﬁed

This bit indicates whether or not the value of the data

byte from the microprocessor meets any of the condi-

tions specified by the scan command used.

Section 3.7.16 on page 69 and Table 3-20 on page 70

describe the conditions.

0: The data byte from the microprocessor meets at

least one of the conditions speciﬁed.

1: The data byte from the microprocessor does not

meet any of the conditions speciﬁed.

Bit 3 - Scan Satisﬁed

This bit indicates whether or not the value of the data

byte from the microprocessor was equal to a byte on the

floppy disk during any scan command.

0: No equal byte was found.

1: A byte whose value is equal to the byte from the

microprocessor was found on the ﬂoppy disk.

Bit 4 - Wrong Track

This bit indicates whether or not there was a problem

finding the sector because of the track number.

0: Sector found.

1: Desired sector not found.

The desired sector is not found. The track number

recorded on any sector on the track is different

from the track address specified in the command

phase.

Bit 5 - CRC Error in Data Field

When the FDC detected a CRC error in the correct sec-

tor (bit 5 of the result phase Status register 1 (ST1) is 1),

this bit indicates whether it occurred in the address field

or in the data field.

0: The CRC error occurred in the address ﬁeld.

1: The CRC error occurred in the data ﬁeld.

Bit 6 - Control Mark

When the controller tried to read a sector, this bit indi-

cates whether or not it detected a deleted data address

mark during execution of a READ DATA or scan com-

mands, or a regular address mark during execution of a

READ DELETED DATA command.

0: No control mark detected.

1: Control mark detected.

Bit 7 - Not Used

This bit is not used and is always 0.

3.5.4

Result Phase Status Register 3 (ST3)

Bits 1,0 - Logical Drive Selected

These two binary encoded bits indicate the logical drive

selected at the end of the command phase.

The value of these bits is the same as bits 1,0 of the SR0

00: Drive 0 selected.

01: Drive 1 selected.

10: If four drives are supported, or drives 2 and 0 are

exchanged, drive 2 is selected.

11: If four drives are supported, drive 3 is selected.

Bit 2 - Head Selected

This bit indicates which side of the Floppy Disk Drive

(FDD) is selected. It reflects the status of the HDSEL

signal at the end of the command phase.

The value of this bit is the same as bit 2 of the SR0 reg-

ister, described in Section 3.5.1 on page 48.

0: Side 0 is selected.

1: Side 1 is selected.

Bit 3 - Not Used

This bit is not used and is always 1.

Bit 4 - Track 0

This bit Indicates whether or not the head of the select-

ed drive is at track 0.

0: The head of the selected drive is not at track 0, i.e.,

TRK0 is not active.

1: The head of the selected drive is at track 0, i.e.,

TRK0 is active.

Bit 5 - Not Used

This bit is not used and is always 1.

Bit 6 - Drive Write Protected

This bit indicates whether or not the selected drive is

write protected, i.e., the WP signal is active (low).

0: Selected drive is not write protected, i.e., WP is not

active.

1: Selected drive is write protected, i.e., WP is active.

Bit 7 - Not Used

This bit is not used and is always 0.

76543210

Reset

Required

Result Phase Status

Not Used

Track 0

Drive Write Protected

Head Selected (Command Phase)

Logical Drive Selected

(Command Phase)

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