One thing unresolved bit of the LCD is the R/~W line.  I had largely assumed that the display was write only in this product, but I was quite wrong as reading is needed at least to poll the 'busy' bit in the status register.  I had found the readLCDnybble function a while back, but at that time 0x8000 was a mystery to me until I found that it was for keyboard column selection.  So why is it used in the LCD routine.  I believe that it serves double duty.  In this case, bit 2 is also connected to LCD R/~W line.

EC45             ; LCD read nybble; return PD in A (shifted LCD data into b5-3)
EC45             readLCDnybble_EC45:
EC45 86 03           ldaa    #3
EC47 97 09           staa    DDRD_9          ; DDRD: b1, b0 output; others input
EC49 86 04           ldaa    #4
EC4B B7 80 00        staa    $8000           ; XXX b2 of 8000 seems to do double-duty as R/~W for LCD
EC4E 14 00 80        bset    PORTA_0 $80     ; PORTA:  b7 high
EC51 96 08           ldaa    PORTD_8         ; PORTD: all data bits
EC53 15 00 80        bclr    PORTA_0 $80     ; PORTA:  b7 low
EC56 14 09 FF        bset    DDRD_9 $FF      ; DDRD:  all pins output
EC59 7F 80 00        clr     $8000           ; XXX b2 of 8000 seems to do double-duty as R/~W for LCD
EC5C 15 08 3C        bclr    PORTD_8 $3C     ; PORTD:  b5,4,3,2 low
EC5F 39              rts

I don't know why bit 2 in particular; this might imply there being double duty on some of the other lines as well.  Or maybe it was just convenient in laying out the traces.