Microprocessing Unit (Mpu); Read/Write Storage; Internal Processing Queue - IBM 5251 11 Maintenance Information Manual

MICROPROCESSING UNIT (MPU)
The MPU (microprocessing unit) is the control center of
the display station. The MPU receives data from the
keyboard and from input/ output controls. The M PU
controls the displaying of data, and the flow of
inforlTlation to and from the controller. It is a processing
unit that is microprogram controlled and performs
internal machine operations such as testing and
comparing data, checking for machine errors, operating
the I/O devices, and storing and getting data from the
read / write storage.
The major parts of the MPU are read/write and
read-only storage, storage registers, work registers, and
an arithmetic and logic unit (ALU).
Planar
Read/Write Storage
Read/write storage is divided into two major parts: a
display regen area and an I/O device control area. The
I/O device control area is also divided into parts for
display control, cable adapter control, and
microprocessing unit work space.
Internal Processing Queue
Each display station keeps a work area large enough to
hold up to 16 frames of commands or associated data.
Commands and associated data are executed from this
queue on a first-in, first-out method.
,--------------------------,
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Microprocessing Unit
Status SWitch
CJr-----~----------1
Keyboard
Adzpter
Work
Registers
r - - - - - l
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Keylock
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Adapter
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To
Controller
ToNext
~
Terminal~
Cable Thru
Feature
Address
Register
Data
Register
Address
Register
Read-Only
Storage
ReadIWrite
Storage
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0-
0 Line Check
e~
LineSync
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0 Internal Check
8-
0 Storage Check
GO
Ready
, - - - - - t - { J l Brightness
Display
Adapter
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___________ J
4
2
T
Address Switches
,-------.
Power
Supply
Horizontal, Vertical,
and Video Signals
Theory 5251 MIM 4-15