Programming adapter to program M4ROM_TANDY and M4ROM_27256 .

Solid electrical contact with the center pins is made the fact that the receptacle holes in the center of the M4ROM boards are slightly closer together than the pins on the programming adapter.

One pair of the 2.0mm pitch pins on top needs to be cut from a 2x7 header to form the polarity key.

Don’t try to use flush cutters for that, the plastic will shatter and you’ll be left with loose/bare pins.

A hobby knife on a cutting board works better, with a paper towel laid over the header to keep the small part from flying away.