Hi, I've been experimenting with connecting an external 32K RAM to an Atmel 89c52, and am having trouble. I wrote a test in which the c52 would write a byte then read it back for every memory location on the chip, and out of 32K I would get about a K of errors. So, the circuit works about 97% of the time. This hints to me that my wiring is ok but something else is wrong.

- the circuit is built on a breadboard, using the c52, a 74ALS573 for address latching.
- I tried this with two different kinds of RAMs, the 20256LC12 and the Dallas DS1230AB nonvolatile, and got similar results.
- I tried this with crystal speeds of 20, 11.0592, and 4 MHz, with no appreciable changes in outcome.
- all chips have decoupling capacitor of 0.1uF.
- I tried 2 different latch chips, in case I had a bad one.
- Same with the mcu.

About the only thing I can think of is that the longish wires I'm using are some sort of problem; the wires range in length from about 1.5" to 4". I have a hard time believing that the length makes too much difference in such a slow circuit, but I'm a digital kid and not very good with issues of noise/interference etc.

Any ideas?