IMP-16
Encyclopedia
The IMP-16, by National Semiconductor
, was the first multi-chip 16-bit microprocessor
. It consisted of five PMOS
integrated circuits: four four-bit RALU chips (Register
and ALU
) providing the data path, and one CROM (Control and ROM
) providing control sequencing and microcode
storage.
The IMP-16 provided four 16-bit accumulators, two of which could be used as index registers. The instruction set architecture was similar to that of the Data General Nova
.
The IMP-16 was later superseded by National Semiconductor's PACE
and INS8900 single-chip 16-bit microprocessors, which had a similar architecture but were not binary compatible.
National Semiconductor
National Semiconductor was an American semiconductor manufacturer, that specialized in analog devices and subsystems,formerly headquartered in Santa Clara, California, USA. The products of National Semiconductor included power management circuits, display drivers, audio and operational amplifiers,...
, was the first multi-chip 16-bit microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
. It consisted of five PMOS
PMOS logic
P-type metal-oxide-semiconductor logic uses p-type metal-oxide-semiconductor field effect transistors to implement logic gates and other digital circuits...
integrated circuits: four four-bit RALU chips (Register
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
and ALU
Arithmetic logic unit
In computing, an arithmetic logic unit is a digital circuit that performs arithmetic and logical operations.The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers...
) providing the data path, and one CROM (Control and ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
) providing control sequencing and microcode
Microcode
Microcode is a layer of hardware-level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high-speed memory and translates machine instructions into sequences of detailed...
storage.
The IMP-16 provided four 16-bit accumulators, two of which could be used as index registers. The instruction set architecture was similar to that of the Data General Nova
Data General Nova
The Data General Nova was a popular 16-bit minicomputer built by the American company Data General starting in 1969. The Nova was packaged into a single rack mount case and had enough power to do most simple computing tasks. The Nova became popular in science laboratories around the world, and...
.
The IMP-16 was later superseded by National Semiconductor's PACE
National Semiconductor PACE
National Semiconductor's IPC-16A/520 PACE, short for "Processing and Control Element", was the first commercial single-chip 16-bit microprocessor...
and INS8900 single-chip 16-bit microprocessors, which had a similar architecture but were not binary compatible.