HP 7942 Service Manual page 27

Channel Interface
7942 and 7946
Table 2-2. Disc Drive Utilities
UTILITY
OPCODE(S) MICRO
ALLOWED* OPCODE UTILITY PERFORMED BY THE DISC DRIVE
(hex) (hex)
32
CO READ FULL SECTOR
32 c4 READ DRIVE TABLES
32
C5
READ RUN TIME DATA ERROR LOG
32
c6 READ ERROR RATE TEST DATA ERROR LOG
32 C7
READ FAULT LOG
30,32 c8 INITIATE PATTERN ERROR RATE TEST
30,32
C9
INITIATE READ ONLY ERROR RATE TEST
30,32 CB INITIATE RANDOM ERROR RATE TEST
30,32 CC INITIATE RANDOM READ ONLY ERROR RATE TEST
30 CD CLEAR LOGS
30 CE PRESET DEVICE
31
F6 WRITE SERIAL NO.
32 F6 READ SERIAL NO.
32 BF
SERVO TEST
32 F7
READ SEEK TIME
*
OPCODE 30 executes utility with no message.
OPCODE 31 executes utility receive message.
OPCODE 32
executes utility send message.
2-6. GENERAL PURPOSE COMMANDS
This command group includes commands which al-
low the host to determine device type and operat-
ing characteristics or to ascertain storage media in-
tegrity. These commands are not considered "real
time" commands and therefore should not be issued
by the host unless it is willing to relinquish control
of the drive for a varying period of time. General
purpose commands are: locate and verify, spare
block, release, release denied, describe, and initial-
ize media.
2-7. DIAGNOSTIC COMMANDS
Diagnostic commands are in tended to assist the
host in isolating problems in the device to the
replaceable assembly level. Some commands allow
protected access to variables or data maintained by
the device (such as error information), while others
cause tests to be performed within the device, or on
a specific area of the storage media. Diagnostic
commands may be modified by complementary
commands. Initialize diagnostic, initialize utility,
and request status are all diagnostic commands.
2-8. TRANSPARENT MESSAGES
Transparent commands compensate for different
types of channels and differences in operating en-
vironments. Transparent commands are intercepted
by the device firmware and modify the normal
command -execution -reporting transaction se-
quence. Transparent commands are explained in
the CS/80 Instruction Set Programming Manual,
part no. 5955-3442.
2-9. HEWLETT-PACKARD
INTERFACE BUS
The Hewlett-Packard Interface Bus (HP-IB)
provides a standardized method of connecting
separate devices (see figure 2-2). The HP-IB per-
mits transfer of commands and data between the
components of a system on 16 signal lines. The in-
terface functions for each system component are
performed within the component so only passive
cabling is needed to connect the system. The cable
connects all controllers and other devices of the
system in parallel.
2-9