Re: using 8051ports

Aliasger wrote:

> Just wanted to know if there is any way to use port P0 and P2 while
> accessing external memory, or do you have to go in for 8255s?
> 
> I want to develop an application which has a really low number of
> components on the PCB.

You can use the ports if you provide adequate decoding, latching
(output), and gating (input).  
To minimize the number of parts, try putting everything on one chip. 
;-)  Look at the STMicroelectronics MicroPSD
(http://www.st.com/stonline/products/selector/450.htm), which provides
an 8051-compatible processor, lots of memory, a little programmable
logic, and I/O pins.

They also have combo chips without the processor that you connect to a
standard 8051, which adds back the I/O lines, as well as provide flash
and RAM.

Thad