RCUBLOK RDEVBLOK 3. The value of the RCHTYPE field (displacement X'05') describes the real
channel type. I 4. The RCHFIOB field (displacement X'OS') is the pointer to the first IOBLOK in the queue and the RCHLIOB field (displacement X'OC') is the pointer to
the last IOBLOK in the queue.
The address of the first RCUBLOK is found in the ARIOCU field (displacement
X'3BS') of the PSA. General register 7 points to the current RCUBLOK. Examine
the following fields:
1. The RCUADD field (displacement X'OO') contains the real control unit
address.
2. The value of the RCUSTAT field (displacement X'04') describes the status of
the control unit.
3. RCUCHA (displacement X'10') points to the Primary RCHBLOK.
4. RCUCHB (displacement X'14') points to the first alternate RCHBLOK.
5. RCUCHC (displacement X'lS') points to the second alternate RCHBLOK.
6. RCUCHD (displacement X'lC') points to the third alternate RCHBLOK.
7. The value of the RCUTYPE field (displacement X'05') describes the type of
the real control unit. I 8. The RCUFIOB field (displacement X'OS') points to the first IOBLOK in the
queue and the RCULIOB field (displacement X'OC') points to the last IOBLOK in the queue.
The address of the first RDEVBLOK is found in the ARIODV field (displacement
X'3BC') of the PSA. General register S points to the current RDEVBLOK. Also,
the VDEVREAL field (displacement X'24') of each VDEVBLOK contains the
address of the associated RDEVBLOK. Examine the following fields of the RDEVBLOK: 1. The RDEVADD field (displacement X'OO') contains the real device address.
2. The values of the RDEVSTAT (displacement X'04'), RDEVSTA2 (displace­
ment X'45'), and RDEVSTA4 fields describe the status of the real device.
3. The value of the RDEVFLAG field (displacement X'05') indicates device
flags. These flags are device-dependent.
4. The value of the RDEVTYPC field (displacement X'06') describes the device
type class and the value of the RDEVTYPE field (displacement X'07') describes the device type. Refer to Figure 69 on page 517 for the list of possi­
ble device type class and device type values.
5. The RDEVAIOB field (displacement X'24') contains the address of the active IOBLOK. Introduction to Debugging 515

6. The RDEVUSER field (displacement X'28') points to the VMBLOK for a ded­
icated user.
7. The RDEVATT field (displacement X'2C') contains the attached virtual
address.
8. The RDEVIOER field (displacement X'48') contains the address of the
IOERBLOK for the last CP error.
9. For spooling unit record devices, the RDEVSPL field (displacement X'18')
points to the active RSPLCTL block. 10. For real 370X Communications Controllers, several pointer fields are defined.
The RDEVEPDV field (displacement X'lC') points to the start of the free
RDEVBLOK list for EP lines. The RDEVNICL field (displacement X'38')
points to the network control list and the RDEVCKPT field (displacement
X'3C') points to the CKPBLOK for re-enable. Also, the RDEVMAX field
(displacement X'2E') is the highest valid NCP resource name and the RDEVNCP field (displacement X'30') is the reference name of the active 3705 NCP. 11. For terminal devices, additional flags are defined. The value of the
RDEVTFLG field (displacement X'3A') describes the additional flags.
12. For terminals, an additional flag is defined. The value of the RDEVTMCD
field (displacement X'34') describes the line code translation to be used.
516 VM/SP System Programmer's Guide