Regarding one of the less-well-documented TMS1000 peripherals, the TMS1025 I/O expander is also used in pairs on several Universal PCBs. It might help to know that, according to the available datasheets, CE (pin 4) is tied to Vss and MS (pin 5) and STD (pin 6) are tied to Vdd on both chips; at least one of these must place them in read mode, as S0-S2 (pins 35-37) are the only control inputs that get toggled.
