Hewlett-Packard Nanoprocessor

The Hewlett-Packard Nanoprocessor from HP (part number 1820-1692[1]) was a small Control-Oriented Processor[2] microcontroller without an ALU nor the ability to add or subtract.[3] It was released in 1974 by HP and used in many HP products.[4] It was packaged in a 40-pin ceramic DIP that dissipated less than one watt.[5]

Die of HP Nanoprocessor

Description

The Nanoprocessor is an 8-bit control-oriented CPU built from nMOS logic. It has an 11-bit address bus that can directly address 2048 bytes of program ROM, expandable to 512 KB with bank switching.[5]

The processor has sixteen 8-bit registers and an 8-bit accumulator. A 1-bit Extend register (E) acts as a carry flag. As well as the 11-bit program counter (PC), it has an 11-bit subroutine return register (SRR) and 11-bit Interrupt Return Register (IRR), each acting as a single-level stack. In place of an arithmetic logic unit, it has a Control Logic Unit (CLU) and a magnitude comparator.[5]

For input/output, the Nanoprocessor has 7 bidirectional control lines as well as 15 input and 15 output ports for 8-bit data transfers.[5]

Code for the Nanoprocessor was written in assembly language using an assembler and loader that ran on an HP 2100 computer.[5]

References

  1. ^ "The 9845 System Architecture". www.hp9845.net.
  2. ^ "The Forgotten Ones: HP Nanoprocessor | The CPU Shack Museum". 9 August 2020.
  3. ^ "HPIB". www.hp9825.com.
  4. ^ "Inside the HP Nanoprocessor: a high-speed processor that can't even add".
  5. ^ a b c d e Nano Processor User's Guide (PDF). Hewlett-Packard.


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