HP-20B dev: LCD


I think I've nailed down everything but the graphic section of the LCD now. Rather than try and find the pattern, I went with the brute force lookup table approach. It's a start--this is ARM code running from the internal SRAM:

And yes, I remembered to run in little endian mode tonight--the port C assignments make a lot more sense now.

PC0         Keypad column 0
PC1 Keypad column 1
PC2 Keypad column 2
PC3 Keypad column 3
PC4 Keypad column 4
PC5 Keypad column 5
PC6 Keypad column 6
PC7 R18 (drives transistor near '232 level shifter)
PC8 ?
PC9 ?
PC10 On key
PC11 Keypad row 0
PC12 Keypad row 1
PC13 Keypad row 2
PC14 Keypad row 3
PC15 Keypad row 4
PC16 J35 (pgm RX connector)
PC17 J33 (pgm TX connector)
PC18 J8-7
PC19 J8-9
PC20 J8-8
PC21 J8-6
PC22 J8-2
PC23 ?
PC24 ?
PC25 ?
PC26 Keypad row 5
PC27 J8-4
PC28 J8-5
PC29 J8-3

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