I've been working on some vintage electronics lately. In the course of this work, I've found that in some cases it is much easier to design a circuit to replace an old DIP chip that has failed than it is to locate the old part. (Actually, the bigger problem is that some of these parts are so old that the only replacements available are 30 years old and may not function at all)

For example, I've replaced two socketed SRAM chips with a single modern SRAM on a daughter board with pin headers aligned so that the whole circuit plugs into the two DIP sockets on the original board.

My question is, what is the actual name for this type of a board? Daughter board? Mezzanine board? I'm trying to figure out how to describe it in the tech notes.

  • 1
    \$\begingroup\$ Adaptor board?... \$\endgroup\$ – Peter Bennett Sep 13 '19 at 22:11
  • \$\begingroup\$ "DIP replacement module" \$\endgroup\$ – Chris Stratton Sep 13 '19 at 22:12
  • 3
    \$\begingroup\$ I once saw a block diagram for a Japanese system where one of the blocks was called the "Utmost Joy Module". That has my vote. \$\endgroup\$ – John D Sep 13 '19 at 22:15
  • \$\begingroup\$ @JohnD, was it a Hitachi design? \$\endgroup\$ – The Photon Sep 13 '19 at 22:39
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    \$\begingroup\$ "Emulation module" You're using modern technology to emulate an older implementation of a given function. \$\endgroup\$ – Dave Tweed Sep 13 '19 at 23:02

It would be called a 'daughter board' if it was intended (usually as part of the original design) to extend the functionality of the main board, eg.

Amiga 1000 WCS Daughter board

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A board which has similar chips to those it is replacing is commonly called a 'replacement module', particularly if it contains RAM.


ZX Spectrum 4116 (lower RAM) replacement module

enter image description here

If it uses eg. an MCU programed to replicate the functionality of a different type of chip it may be called an 'emulator'.



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A board with no parts on it for using chips or modules with a different pinout is called an 'adapter'.


Amiga 3000 SIMM ZIP Ram Adapter

enter image description here

As always there are overlaps and exceptions to these definitions. The word 'module' is often used to describe small boards with various generic functions (CPU module, RAM module etc.), so 'replacement module' could just be a module to replace another one.

  • \$\begingroup\$ Also, adapters that take pretty much anything and make them fit into DIP sockets are commonly referred to as "breakout boards". \$\endgroup\$ – Hearth Sep 14 '19 at 1:48
  • \$\begingroup\$ To me 'breakout board' means an adapter that makes the pins of a device available in a more accessible format, for eg. testing or plugging into in breadboard. The OP describes a board which plugs into multiple DIP sockets, specifically dimensioned to fit the particular device. \$\endgroup\$ – Bruce Abbott Sep 14 '19 at 2:29
  • \$\begingroup\$ Thank you! Very helpful. \$\endgroup\$ – David Hoelzer Sep 14 '19 at 4:02
  • \$\begingroup\$ Sometimes you also find the term 'piggyback pcb' \$\endgroup\$ – po.pe Sep 14 '19 at 6:54
  • \$\begingroup\$ There is also "interposer" which acts as tracking between cards. Typically to correct a pin out issue \$\endgroup\$ – JonRB Sep 14 '19 at 7:38

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