Commodore 1581 - Page 112

Most of the tasks that the Controller can be asked to perform
require parameters. The parameters are also placed in a 'mailbox'
location for the Controller to access (prior to placing the command
byte into the queue, of course). These parameters can be either the
physical or the logical parameters, depending on what the command
expects to see. Logical parameters are placed in HDRS as two consecu
tive bytes of track, sector. Physical parameters are also placed in HDRS,
but in addition the side must be specified (in SIDS). Commands that
require logical parameters must translate them into physical param
eters at some point in their execution. The logical parameters are
translated into physical parameters by a vectored routine called
TRANSTS, and are written into HDRS2 and SIDS. The DOS will always
pass logical parameters, and uses only the Controller commands that
expect to see logical parameters. However, the Controller is also
allowed to put jobs in its own queue, so it needs to pass physical
parameters as well as logical.
Mailbox Locations of the Controller
name
JOBS
HDRS
HDRS2
SIDS
CACHE
CACHEOFF
BUFFCACHE
address
$0002
ftOOOA
$000B
$001C
$01BC
$01CD
$01CE
$01D6
$008B
$Q09F
S0QA7
$0C00
purpose
JOB queue for Controller commands (JOBS 0-8).
Each JOB uses 1 byte. The last 2 locatioas
($09,$0A) are reserved for BAM jobs only!
Logical or physical track, sector for each of
the jobs in the JOB queue (2 bytes per job).
Translated (physical) track, sector for each
of the jobs in the JOB queue (2 bytes per job).
Physical side for each of the jobs
in the job queue (1 byte per job).
Pointer to BUFFCACHE below.
Offset into the track cache buffer.
(1 byte per job).
20 pages for track cache.
Associated with each of the nine Job Queue locations (Jobs 0
through 8) are nine 256 byte buffers (buffers 0-8), beginning at
location $0300. Data passed from/to a particular Job during its execu-
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