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. . 20.
Programming. The Disc Controller (combined circuitry of the Data Channel
Card and the Command Channel Card) uses
tw
0
select codes, one for "data" (higher
priority) and one for "command" (lower priority). With the exception of STC, used
only to initiate a disc {:ransfer, and CLC, used to abort a transfer, only DMA sends
. commands and data to the "data" select code. Address selection and status use the
. "command" select code. The bit format of track and sector address words (OTA/B)
for the 12606A differs from that for the 12606B. This is why the command select
code is presented in two tables: table 2 (12606A), and table 3A (12606B). For the
same reason a sample program is presented in two tables: table 3 (12606A), and
table 3B (12606B).
,
Table 2. Command Select Code (12606A)
OTA/B
Outputs track and sector address to Disc Controller:
LIA/B
.BIT 15:
DIRECTION: "1";;: WRITE DISC; "0";;: READ DISC
BITS. 14-8: TRACK SELECTION: OCTAL 000-177
BIT 7:
Not Used
BITS 6-0:
STARTING SECTOR ADDRESS: OCTAL 000-131
Inputs status word:
BIT 15:
SECTOR FLAG: "1 ";;: Sector indicated by bits 14-8
is not accessible on this revolution.
BITS 14-8: Address of "NEXT SECTOR", OCTAL 000-131;
_
BIT 7:
BIT 6:
BIT 5:
BIT 4:
BIT
3:
BIT 2:
BIT
1:
BIT 0:
if BIT 15 is not;;: "1 ", this sector may
be
accessed
on the same revolution with the probability
indicated in Figure 2.
"1" ;;: Disc is
up
to speed.
"1" ;;: Head change in progress; used only for
diagnostic purposes.
ttl" Sector address coincidence; used only for
diagnostic purposes.
Not Used
"1"
=
Abort; transfer not possibly completed.
"1"
=
WRITE ENABLED; current track is not
protected.
"1" ;;: READ PARITY ERROR.
l"1
tt ;;:
BUSY; transfer has been initiated, is in
progress, or is being terminated.
Note: Initiation of a new transfer clears all error status bits.
l2606-900i'
Changed 3 Dec. 1969
. .: ".<.> •.
7
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