Table of Contents
Advertisement
Both command types have status codes as f0llows:
S7
1
=
Drive Ready
S6
1 =
Drive Write-Protected
S5
1
=
Record Data Mark deleted, Read Sector command; Write
Fault, Write Command.
S4
1
=
Record not found.
S3
1
=
CRC Error
S2
1
=
Lost data.
Computer did not
res~ond
in time.
Sl
1 =
Read Command: Data register fu:'l; Write Command: Data
Register empty
SO
1
=
Command in progress, device Busy
Unless the drive becomes not-ready after track selection, status bit
7 should always be logic 1.
Similarly, status bit 6 should always be
logic 0,
unless
diskette
becomes
write-protected after
track
selection.
S5 at logic 1 is not an error for a Read operation.
For a Write
operation, it causes T/DOS to give an error message with status code
equal to one of
40 -
4F.
S4 at logic 1 causes T/DOS to write
SEE~
ERROR on the console screen.
S3 at logic 1 causes T/DOS to give an
error message with status 08.
S2 at logic 1 causes T/DOS to give ar.
error message with status 04.
Sl and SO are not considered errors.
A.2.4
TYPE IV
COHMA~D
The single Type IV command, Force Interrupt, causes the 1791
devic~
to generate an interrupt to the host CPU immediately,
or upor.
completion of certair. specified conditions.
If received while ar.y
Type I, II, or III command executing,
th~
Type IV command resets tte
SO status bit, but leaves Sl - S7 unchanged. If received at any other
time, the Type IV command resets SO and Lpdates or resets Sl - S7.
The 'I'ype IV command
gen~rCotes
no er ror messages.
A-3
Advertisement
Table of Contents
