On Thu, Jun 16, 2016 at 11:08 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
Subassemblies (like PCBs) have part numbers with 2
groups of 5
digits. The first group is the model number of the instrument that
first used that subassembly, padded with leading zeros. So for
example the CPU data path (ALU and registers) board in an
HP9830 is an 09810-66514, as it was first used in the HP9810.
On some early HP gear (1960s), the subassemblies and model-specific
parts have a 4x5 or 4x4 part number, with the base model number as the
first part, rather than the later 5x5.