The 6331-1 PROM used for the colour palette is not very new. So are a bit expensive and need a special programmer. The average programmer, like the TL-866, don't supply the right programming voltage for it. So being bipolar it needs something more specific and this is it. A manual programmer where you have to flick switches for the address then load the value for that address. This board is very similar to what was published in the early eighties by ETI and probably a lot of other magazines as well. The PROMs are one time programmable so need to take it nice a slow.

Have all the bits so will be building it like it's 1984.

Quick specs of the 6331-1

• Memory Capacity: 256 bits, organised as 32 words × 8 bits.
• Package Type: Narrow 16-pin Dual In-line Package (DIP).
• Technology: Schottky Bipolar architecture using Nickel-Chromium (NiCr) fuses.
• Speed Designation: The -1 suffix indicates a high-speed variant of the standard 6331 chip
• Equivalents:  82S23 or 82S123 from Fairchild, 74S188 or 74S288 from TI , 74S188 or 74S288 from Harris