I have a requirement in a memory mapped I/O scheme to select some 4 different memory devices - EEPROM, RTC, and two RAMs. And all of them are 2K devices. I was just wondering if I can use a 4515 ( 4 to 16 decoder )instead of discrete gate logic with 7400. 7432 etc using the A15, A14, A13 and A12 lines. ( only the 0xC000 to 0xFFFF area is available. )

With the 4515, I plan to use the ALE for the strobe pulse. This means that the relevant chip will be selected AFTER the ALE sttles to low. However if I use discrete gates, this will happen almost at the MIDDLE of ALE pulse. Can this differnce lead to any problem ? For information, I am running with a 6 MHz crystal and the MCU in 6 clock mode.

Any suggestions / pitfalls to avoid ?

Thanks

Raghu