Alphanumeric Display at the TLX+

-> Diagram
-> Sample program


PLD Equations:

  PLD16V8  ; Keyboard and LCD control
           ; MCT Paul & Scherer
           ; Mikrocomputertechnik GmbH

  /CS0 /CS1 /CS2 /CS3 A0 A1  A2       A3      /RD    GND
  /WR   NC   NC   NC  NC NC /CS273-2 /CS273-1 /CS244 VCC

  CS244.OE   = VCC
  CS244      = CS1*RD* A0*/A1*/A2*/A3
  CS273-1.OE = VCC
  CS273-1    = CS1*WR*/A0*/A1*/A2*/A3
  CS273-2.OE = VCC
  CS273-2    = CS1*WR* A0*/A1*/A2*/A3

The chip selects CS244 und CS273-2 are at the same addresses! But one is only for write and the other only for read, so this is not a problem. Thus still 14 addresses are available for other selects.

The example above uses CS1, but may be changed to use CS0, CS2 or CS3 by modifying CS in the GAL equations. Also the addresses can be changed.

In the example the addresses are as follows:

Chip select Address
CS244
CS273-1
CS273-2
0x1
0x0
0x1

Please note that these are the GAL addresses, not the target's absolute addresses.

The absolute address is computed as follows:

    base address for the chip select
  + GAL adress shifted left by one
  + one
  ----------------------------------
  = absolute address
  ==================
www.mct.net