I'm morbidly curious about the Speak and Spell now, since afaik the TMC0270 cpu it uses is a hybrid of the cpu portion of the tms0980 (9-bit words), the VFD drivers of the tms1100 (0980 normally can only drive an LCD), a very large output PLA (handles A thru Z, 0 thru 9, ', _, +, -, and maybe one other symbol which isn't used?), and a bunch of added logic to re-use a few of the segment pla pins as a direct i/o output from the accumulator to talk to the tms5100 chip and read back speech status from it overriding the usual K input bus.

The segment outputs of the PLA are listed here (from experimentation on a 1978 'test release' speak and spell which has a slightly different rom from the later ones):

Pinout for tmc0270 (based on a bunch of sources but no decap yet) is here:


Last edited by Lord Nightmare; 11/28/14 05:33 PM. Reason: fix links

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