For a matrix of LEDs it is very common to use a row/column multiplexing scheme. For best advice I think you should consult here with Erik Malund. I think he as designed many a LED matrix.

And.....god forbid...do not use the 82C55. This ancient relic is not worth the effort to interface or the cost of the silicon it is built on. I would use long shift registers instead. If you pick a derivative with an SPI bus you can clock these at multiple mHz.


Michael Karas