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IBM 1801/1802 Processor Controller
The IBM 1801 and 1802 Processor-Controllers are stored
program computers, composed of a central processing unit
(CPU), main storage, and channel control circuits.
Either the 1801 or 1802 may be used in the 1800 sys-
tem. The 1802 includes circuitry and control for connection
and operation of the IBM 2401 Magnetic Tape Unit. The
1801 has no standard provisions for magnetic tape units.
Each processor-controller is available with five main
storage capacities: 4,096; 8,192; 16,384; 24,576; or 32,768
words. Total system main storage capacity can be expanded
in 8,192 word increments to 65,536 words with the addi-
tion of an IBM 1803 Core Storage Unit. In systems with
main storage capacities above 32,768 words, 24,576 words
are located in the processor-controller. The remaining main
storage words are located in the 1803 Core Storage Unit.
Standard features of the processor-controller include three
hardware index registers, 12 levels of priority interrupt
(expandable to 24 by special feature), three data channels
(expandable to 15 by special feature), three interval timers,
an operations monitor, and an operator's console.
The processor-controller contains a binary stored-program
CPU. Within its basic design, the CPU has interrupt and
cycle-stealing capabilities which are used in controlling the
various I/O devices to be attached to the using system.
Index registers and indirect addressing are provided to
facilitate address modification and programming.
A complete instruction set with powerful options gives
the computer very high performance for tasks normally
encountered in data acquisition and process control appli-
cations.
PROCESSOR-CONTROLLER CONSOLE
The processor-controller console (Figure 1) provides the
means for manual control of the processor-controller during
debugging or operation phases.
The basic operating features and controls provide the
facility to:
1.
Start or stop instruction execution.
2.
Address main storage.
3.
Set up and store data or instructions.
4.
Communicate with the program via sense or program
select switches.
5.
Control the cycling rate in the run. single main storage
6
IBM 180e Operating Procedures
cycle, single instruction, or single step modes.
6.
Interrupt the program manually.
7.
Trace each instruction.
8.
Reset all control circuitry and main storage.
9.
Turn power on and off.
10.
Indicate basic machine conditions and status.
11.
Display main storage words and register data.
12.
Write or clear storage protect bits.
13.
Clear main storage.
14.
Allow program execution with an internal error such
as invalid operation, parity, or storage protect.
I
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