ACT apricot - Data Transfers

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Error

FLOPPY DISK INTERFACE

Logic

high

indicates a

matching

track

number

was

not

located

within

a sector ID field during

the

verification operation.

The

bit

is also set

*iggdf

the

FDC fails to

detect

a logic low

on

the

R

input

following a Restore command.

Protected Inverted copy of

the

WPR T

input

from

the

drive. Logic

high

indicates

that

the

selected

disk

drive

contains

a

write

protected disk.

Not

Ready

Inverted copy of

the

READY

input

from

the

drive. Logic

high

indicates

that

the

drive is

not

ready for a

data

transfer operation.

Data Transfers

Transfer of

data

to

and

from

the

disk

is controlled by

the

two

Type 2

commands,

Write Sector

and

Read Sector. Prior

to issuing

the

command

to

the

Command

Register,

the

Sector Register

must

be loaded

with

the

desired sector

number,

to

determine

the

source/destination

of

the

data.

Termination

of

the

command

(successful or otherwise) is

signified by

an

interrupt

request

to

the

PIC. Both

command

operations are

prematurely

terminated,

if

the

disk drive is

not

ready for

the

transfer operation, as indicated by

the

READY

input.

The

format

of

the

data

transfer

commands

is detailed

below.

D7

1

0

0

m

1

0 1 m

Type 2

Commands

1 1

1 1

DO

Command

U 0

Read

Sector

U 0 Write

Sector

m =

Multiple

Record Flag

U = Update

SSO

Both

commands

contain

a

Multiple

Record Flag

bit

and

an

Update SSG bit.

The

Update

SSG

bit

is used to select

the

disk side for

the

data

transfer operations

and

affects

the

Table of Contents

Other manuals for ACT apricot

Service Manual305 pages