Alternative WP34S flashing using Arduino

[orcinus]

Actually, RS-232 wouldn't really help you, as it's not TTL.
On top of that, on an average computer (with a serial port), the voltages in question are usually in the [-13,13] V range, which would do a very quick job of frying your TTL device.

(In other words, you'd need a logic level shifter. And then you're back to square one - might as well use a USB-to-serial adapter if you're putting extra electronics in the signal path either way.)