I am using the Intel 80C51BH.

The reason why I am using a crystal is because the processor includes an on-board serial port, and I need to get a 100% accurate frequency, or I will lose characters on the port.

Would it be valid to connect an inverter of any technology (CMOS/TTL) in parallel to the 18.432Mhz crystal, and connect 2 12pF capacitors from each end of the crystal to ground? and take any end of the crystal and connect it to the crystal input of the microprocessor?

In other words, would the above setup work the same as connecting an 18.432Mhz crystal to XTAL1 and XTAL2 on the microprocessor?



I was thinking of the same thing, but when I thought about it, I was thinking the 555 timer. Since I will be using the on-chip serial port, this external clock must be accurate.

Neil, thanks for the useful info on the RESET, but I doubt that will help me.

and I got one more question.

I have RAM and EEPROM that share the same data bus and address bus that the microprocessor provides. Provided that the RAM and EEPROM's are enabled (CE' set to logic low), and the data read is disabled, (OE' pin is high), and the data write on every device (except the EEPROM when I will send data to) is disabled, could I just add the parallel port to the bus, and somehow send a sequence of bytes, where one byte represents the "NOP" code, so the processor won't do anything but increment the program counter (the EEPROM address), and another byte represents the actual data being written to the EEPROM?

If I can, I want to make a system without the need of extra buffers.

somehow, I think this can be done.