Jay Logue's Templates Get You Started Building FLIP CHIP Add-In Boards for Vintage DEC Computers

Vintage computing enthusiast Jay Logue is hoping to bring fresh blood into the world of add-on hardware for the Digital Equipment Corporation (DEC) PDP and VAX range of computer systems — by releasing open hardware PCB templates for FLIP CHIP add-in boards.

"FLIP CHIP modules were used in a range of DEC computer systems, including the PDP-7, PDP-8, PDP-9, PDP-10, PDP-11 and VAX," Logue explains. "For PDP-11s, they define the standard form-factor for modules that plug into the system's UNIBUS or QBUS backplanes."

With DEC having gone defunct in 1998 after its acquisition by Compaq, and the VAX and PDP lines having been discontinued long before that, there aren't many people making new FLIP CHIP modules these days — which is what Logue is hoping to change with his KiCad template files.

"These templates were designed to match the physical specifications found in the Digital Logic Handbook 1975-76, pp 6-10," Logue writes. "Where authoritative specifications were unavailable (such as the width for hex-height boards) dimensions were taken from actual hardware."

As well as the templates, which allow anyone to begin building a FLIP CHIP module in KiCad, Logue has also released a set of manufacturing guidelines for compatible PCBs: ENIG or hard gold finish; beveled edges on the connector; and a thickness of 1.4mm to 1.6mm — with a note that the latter is somewhat outside DEC's original specification of 0.056" (+/-0.005), but easier to find at low-cost PCB manufacturing houses.

The templates, and supporting KiCad libraries, have been published to Logue's GitHub repository under the permissive Creative Commons-Attribution 4.0 International License.