Hewlett-Packard 1818-2xxx Series
Written by Accutron on 2008-01-21

Devices included in this entry:

HP 1818-2056A (28-pin grey trace cerDIP)
HP 1818-2251A (28-pin cerDIP)
HP D1818-2800 (28-pin perforated grey trace LCC)
HP A1818-2817 (28-pin perforated grey trace LCC)
HP C1818-2833 (28-pin perforated grey trace LCC; pictured in thumbnail)

HP is notorious for anonymous ICs. A HP part number tells you nothing, except that it is a part used by HP in one of their systems. Some HP parts are proprietary in-house devices, while others are simply re-branded off-the-shelf chips from another vendor such as Intel or Mostek. Part number cross references can be found for HP's renumbered third party devices, but their in-house parts are either poorly documented or completely unidentified.

The 1818-2xxx devices pictured here are believed to be proprietary 28-pin ROMs for various HP systems, but their exact function is unknown.

Hewlett-Packard 1818-2056A, 28-pin grey trace cerDIP with gold pins and cavity lid. System of origin is unknown.


Hewlett-Packard 1818-2251A, 28-pin white cerDIP. System of origin is unknown.


Hewlett-Packard D1818-2800 and A1818-2817. These are obvious examples of in-house HP parts, and one of the most unusual chip carriers ever manufactured. These devices are believed to be ROM ICs for the HP 9835A or similar.


Hewlett-Packard C1818-2833. Note that the ceramic substrate is thinner on this chip than on the examples pictured above, and the trace pattern is slightly different.

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