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completion of a power-on. After completion of power-on and/ or IML, the
program load display is shown on the operator console.
Natively Attached Devices
Support Bus Adapter
Up to four devices can be natively attached to a 4381 Processor via the
1/0
bus of
the support processor. The natively attached devices attach to channel 0 in 4381
uniprocessors and to channel 0 in channel group 0 in 4381 dual processors via the
local channel adapter. The following devices can be natively attached:
•
Required 3205 Color Display Console, 3278 Display Console Model 2A, or
3279 Color Display Console Model 2C
Up to three additional devices, which can be any combination of 3205, 3278
Model 2A, and 3279 Model 2C consoles, 3268 Printers Model 2, 3268 Color
Printers Model 2C, and 3287 Model 1, lC, 2, and/or 2C Printers with the
exception that 3205 displays cannot be installed in a 4381 configuration that
contains a 3278 Model 2A or 3279 Model 2C display
The additional 3205, 3278 Model 2A, or 3279 Model 2C displays can be used as
alternate and/ or additional consoles, as supported by the operating system utilized.
The 3287 and 3268 Printers can be used for hard-copy backup of the 3205, 3278
Model 2A, or 3279 Model 2C displays. The 3287 Printer is a desktop printer with
a print speed of 80 characters per second (Models 1 and lC) or 120 characters per
second (Models 2 and 2C). The 3268 Printer provides faster printing (up to 340
characters per second). The 3287 Models lC and 2C and the 3268 Model 2C
provide printing in colors.
The support bus adapter provides an interface between the support processor and
the instruction processing function and channel hardware. Via this direct path, the
support processor can access maintenance hardware (maintenance logic chips) in
the instruction processing function and channels.
This interface enables the support processor to perform scan-in operations to
initialize logic and scan-out operations to obtain status information after an error is
detected during processor operation (see discussion of scan-in, scan-out, and scan
rings in Section 60:10). The scan-in and scan-out facilities are used by
maintenance programs to isolate faults and verify repairs. The support processor
also issues commands (such as start clocks and stop clocks) to the maintenance
chips via the support bus adapter interface.
The support bus adapter also provides an interval timing facility for
power-monitoring microcode.in the support processor. This adapter also drives the
system and wait indicators and the lamp test switch on the switch on the operator
control panel.
Implementation of the preceding functions is the same in 4381 and 4341
Processors. However, in 4381 Processors the support bus adapter is also used for
microcoded communication between the instruction processing function and the
....,,,
46
A Guide to the IBM 4381 Processor
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