Help identifying IC

The mid-70s saw a plethora of dedicated-logic LSI TOD clock chips in 24-28 and sometimes 40 pin packages. Most prevalent IME were those made by National, Mostek and Fairchild. Going by the labelling for the other two chips, fair chance the ID of the big chip is staring right at us: MPS 7123. Micro Power Systems and Commodore Semiconductor Group used chip ids of the form MPSxxxx, although I have nothing for specifically MPS7123. The former would fit the battery operation. Try tilting the IC obliquely to the light and viewing angle if you haven't, often shows up a remnant impression of printing on the IC. I never did see a TOD clock chip in a gold-topped package - they were generally targetted for the low-cost consumer market - although by the date code it may be early enough, in the period that consumer products would have such packages. The clock chips were pretty straightforward but varied in options: generally 2 power pins 2 oscillator pins (for the multiplexing) 50/60hz input pin (for TOD timing if separate from internal oscillator) 4 or 6 digit-drive pins 7 segment-drive pins some setting/mode control pins which could be either switched direct to a power rail or multiplexed with isolation diodes off the digit pins often an AM/PM indicator pin alarm control output pin (There were some for non-multiplexed display drive but that would be >28 pins.) (Some had BCD rather than 7-seg numeral outputs) So, yes, it's hard to say, could be a dedicated TOD clock, could be an evaluation module for something like a multi-digit decade counter IC. Perhaps a start-stop timer, 3 switches: start / stop / reset. Not difficult to trace out, could see if there are any other pins that might be for external connections like timing control or counter inputs. On 2018-Jan-20, at 6:06 PM, Josh Dersch via cctalk wrote: