HEWLETT-PACKARD 9831A
The Hewlett-Packard HP 9831 is a BASIC-language computer introduced in mid-1977. It appears only in the 1978 catalog.

It is very similar in mechanical and electrical design to the 9825 and nearly identical software-wise to the 9830. In fact, most of the internal parts are prefixed with 09825, meaning they were originally designed for the 9825 computer. For instance, the keyboard assembly is 09825-66537.

The 9831 (and 9825) use a three-chip central processing unit. The three chips are:

  • Binary Processor Chip (BPC)
    • 59 byte-addressable instructions
    • similar to HP 2100 and HP 21MX instructions
    • Two general purpose 16-bit registers (A and B)
    • Program Counter P
    • Stack Pointer
    • Flags
  • Input/Output Chip (IOC)
    • 12 instructions
  • Extended Math Chip (EMC)
    • 15 instructions
    • Binary Coded Decimal operations

I am interested in finding any 9831 machines, ROMs, manuals, documents or other material, including information on the BPC processor. If you have any such equipment or documentation, please send me an e-mail!

I have more information and photographs here.


 
 

Plug-in ROM
HP 98218A
9885 Flexible Disk ROM

 

09831-67905
BASIC Language plug-in ROM for use in the 9831A


Comments to Dan Veeneman
Last updated January 27, 2015