The most common LCD module is the DMF690N produced by OPTREX. Some previous versions exist, with more failure and less contrast. This unit has its own PCB. The LCD panel is a dot matrix of 640*64 pixels, the NRD7482. It is driven by nine CMS chips. One SED1610 : a 86 lines driver and eight SED1600 : 80 rows dirvers. Another IC is devoted to voltage generation. The module is connected by a special ribbon with 14 links on SK5.
LCD Ribbon signals:
14 is the left one, 1 is on the right in top view.
Pin Symbol Level Function
1 VDD - Base supply (0V)
2 VSS - Power supply for Logic
3 VLCD - Power supply for LCD driving
4 LP H>L Date Latch signal
5 FR H/L Alternate signal for LCD driving
6 YDIS L Display off signal
7 NC - No connection
8 DIN H Frame signal
9 XSCL H>L Clock signal for shifting serial data
10 NC - No connection
11 D0 H/L Display data
12 D1 H/L Display data
13 D2 H/L Display data
14 D3 H/L Display data
All of these signals are directly managed by the blink. It builts the screen by reading directly in the memory the different character set and screen base. The cursor is hardware managed too. Refer to The Screen File section for more informations.