Initially, we just wanted to test the interface to the LCD. We were able to write a simple test pattern into the external RAM upon startup, then read it back to refresh the LCD. Using this configuration we determined that we need at least a 16 Mhz clock to refreash the LCD without noticable flicker. Clock frequencies of 10 Mhz are still acceptable for testing, but in certain lighting conditions, the flicker is noticible. at 8Mhz, the flicker is extremely noticible.
The LCD interface is essentially accessed in halves. Data is clocked in one byte at a time, but one nibble goes to writing the upper half of the display while the other nibble goes to writing the lower half.
The LCD also has special power requirements. We had to construct our own power supply to operate it.