A report on Accumulator (computing)

Walther WSR-16 mechanical calculator. The row of digit-wheels in the carriage (at the front), is the Accumulator.
Front panel of an IBM 701 computer with lights displaying the accumulator and other registers

Register in which intermediate arithmetic logic unit results are stored.

- Accumulator (computing)
Walther WSR-16 mechanical calculator. The row of digit-wheels in the carriage (at the front), is the Accumulator.

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A Nova system (beige and yellow, center bottom) and a cartridge hard disk system (opened, below Nova) in a mostly empty rack mount.

Data General Nova

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Series of 16-bit minicomputers released by the American company Data General.

Series of 16-bit minicomputers released by the American company Data General.

A Nova system (beige and yellow, center bottom) and a cartridge hard disk system (opened, below Nova) in a mostly empty rack mount.
Data General Nova 1200 front panel
A Nova 1200, mid-right, processed the images generated by the EMI-Scanner, the world's first commercially available CT scanner.
Nova 1200 CPU printed circuit board. The 74181 ALU is the large IC center-right.
Running Nova 840 (The front panel has been replaced with one from a 1220)
Data General Nova 3
Data General mN601 microprocessor
Data General software on punched tape

As the complexity of a flip-flop was being rapidly reduced as they were implemented in chips, the design offset the lack of addressing modes of the load/store design by adding four general-purpose accumulators, instead of the single register that would be found in similar low-cost offerings like the PDP series.

A PDP-8 on display at The National Museum of Computing in Bletchley, England. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8.

PDP-8

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12-bit minicomputer that was produced by Digital Equipment Corporation .

12-bit minicomputer that was produced by Digital Equipment Corporation .

A PDP-8 on display at The National Museum of Computing in Bletchley, England. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8.
A PDP-8 on display at The National Museum of Computing in Bletchley, England. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8.
An open PDP-8/E with its logic modules behind the front panel and one dual TU56 DECtape drive at the top
A "Straight-8" running at the Stuttgart Computer Museum
PDP-8/e at the Living Computers Museum.
PDP-8/I core memory stack
One of three inter-connected modules that make up a PDP-8 core memory plane.
One of three inter-connected modules that make up a PDP-8 core memory plane. This is the middle of the three and contains the array of actual ferrite cores.
One of three inter-connected modules that make up a PDP-8 core memory plane.

It also has only three programmer-visible registers: A 12-bit accumulator (AC), a program counter (PC), and a carry flag called the "link register" (L).

White ceramic Intel C4004 microprocessor with grey traces

Intel 4004

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4-bit central processing unit released by Intel Corporation in 1971.

4-bit central processing unit released by Intel Corporation in 1971.

White ceramic Intel C4004 microprocessor with grey traces
The Unicom 141P is an OEM version of the Busicom 141-PF.
National Semiconductor was a second-source manufacturer of the 4004, under their part number INS4004.
Two C4004 DIPs, with one opened to show the die
Intel 4004 architectural block diagram
Intel 4004 DIP chip pinout
In the lower-right corner of the CPU are the initials "F.F."
The ceramic C4004 variant without grey traces
The ceramic D4004 variant
The plastic P4004 variant

He also modified the Branch Back (return from subroutine) instruction to clear the accumulator.

MIX

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Hypothetical computer used in Donald Knuth's monograph, The Art of Computer Programming .

Hypothetical computer used in Donald Knuth's monograph, The Art of Computer Programming .

rA: Accumulator (full word, five bytes and a sign).

HP 1000 E-Series minicomputer with a 9895A dual 8-inch "flexible disc memory" drives.

HP 2100

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Series of 16-bit minicomputers that were produced by Hewlett-Packard from the mid-1960s to early 1990s.

Series of 16-bit minicomputers that were produced by Hewlett-Packard from the mid-1960s to early 1990s.

HP 1000 E-Series minicomputer with a 9895A dual 8-inch "flexible disc memory" drives.
HP 2115A Computer pictured without its power supply.
HP 2100 computer (upper left), shown with two 7970 tape drives, 7900-series hard disk, 2748 paper tape reader and a 2767A impact printer. The separate front-panel switches and lights were replaced with light-up pushbuttons, which had a tendency to burn out.
HP 2100A Computer
An HP 2647A graphics terminal connected to an HP 1000 E-Series machine.
HP Model 9830A desktop computer with optional Model 9866 thermal printer.

This favored designs with few registers and most storage in RAM, which in turn influenced the instruction set architecture (ISA) to use a memory-memory or memory-accumulator design.