Finished building a prototype mezzanine board and testing with the IM6100 (PDP-8 on a chip) in the 560Z board today. Full writeup: http://www.glitchwrks.com/2017/05/03/gw-osi-ram1-universal-ram There are a couple of tweaks required, but I should be doing a first production run of boards before long. This board is: * 128 KW, 12-bits * Optional memory management/bank switching * No hard-to-find/expensive ICs (8T26, et c.) * All through hole * Includes lamp register mezzanine header * Largeish prototype area The lamp register is on a mezzanine for a few reasons. First off, octal vs. hex grouping! It really throws me off to try and interpret one on the other. Second, it allows remote mounting on a ribbon cable, i.e. board can be mounted to a front panel. Third, I'll likely design a 7-segment version. Thanks, Jonathan