Why not use a couple of transistors for the level translation/inversion?

Or just drive the PIC pins directly with series R (1k on Rx, 100R on Tx)
and invert the logic if you're bit banging?
It is a PIC isn't it <G>? If it isn't, you're going to need clamp diodes
to VCC and Gnd for the Rx line.

And if you are going to use a SMT logic device, I recommend the 74HC14
(Schmidt).
I use it all the time in our lab on 50' cables at 19.2kbaud without problems.
The official Rx spec for RS232 says anything about 3V is a Mark and lower than
-3V is a space, and -3 to 3 is undefined (so 0V is ok). In other words, you get
a minimum of 2V of noise margin using a 74HC14 driving a 'normal' RS232
chip like the 1489.

John Pearson wrote:
>
> Is a 7404 or equivalent available in an 8 pin dip? Or perhaps is there a way to mount a SMD 7404 onto an 8 pin DIP adaptor, or a SIP adaptor?
>
> What I want to do is to try to use an rs232 serial connection with a 5Volt mpu using a very short cable and low speed (9600 max).
> Thanks

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