The Prolific PL-2303 chip seems to be a quite popular solution for USB to (classic) serial converters - in fact, all of the products I have seen until now use it. Just not all the manufacturers include the MacOS X driver.
UPDATE:
A new version of the PL2303 MacOS X driver is now available from the Prolific support center site (as of 20060208, look for the file named md_pl2303H_HX_X_dmg_v1.1.0b1.zip).
The following info is obsolete now a new driver is available, and is just kept for reference:
It used to be available from the Prolific tech support site, but that site seems to be currently offline. For that reason, a copy of the v1.06 OSX driver I found on the net is temporarily available here: ProlificUSBSerialOSX106.zip
The driver works with Panther (MacOS X 10.3), but regularly generates error messages like the following on the console on some machines:
mach_kernel: ttyioss800000?: dequeueData ret 3
mach_kernel: 00000?: dequeueData ret 3
Fortunately, someone at macOSXhints created a patch (cache) for the driver binary that removes the messages. Instead of downloading a graphical hex editor, you probably want to use this method (cache) for the actual patch step.
The procedure boils down to something like this:
(become root, unload driver, change to kext dir, make a backup copy, make file writable, apply binary patch, restore permissions, reload driver)
Warning: this worked for me on my system with the driver available from this page, but all sorts of things may go wrong on yours.
If root access on your system is not enabled, look at the EnablingRootOnMacOSX page.
UPDATE:
A new version of the PL2303 MacOS X driver is now available from the Prolific support center site (as of 20060208, look for the file named md_pl2303H_HX_X_dmg_v1.1.0b1.zip).
The following info is obsolete now a new driver is available, and is just kept for reference:
It used to be available from the Prolific tech support site, but that site seems to be currently offline. For that reason, a copy of the v1.06 OSX driver I found on the net is temporarily available here: ProlificUSBSerialOSX106.zip
The driver works with Panther (MacOS X 10.3), but regularly generates error messages like the following on the console on some machines:
mach_kernel: ttyioss800000?: dequeueData ret 3
mach_kernel: 00000?: dequeueData ret 3
Fortunately, someone at macOSXhints created a patch (cache) for the driver binary that removes the messages. Instead of downloading a graphical hex editor, you probably want to use this method (cache) for the actual patch step.
The procedure boils down to something like this:
(become root, unload driver, change to kext dir, make a backup copy, make file writable, apply binary patch, restore permissions, reload driver)
Warning: this worked for me on my system with the driver available from this page, but all sorts of things may go wrong on yours.
> su - # kextunload /System/Library/Extensions/ProlificUsbSerial.kext # cd /System/Library/Extensions/ProlificUsbSerial.kext/Contents/MacOS # cp ProlificUsbSerial ProlificUsbSerial.old # chmod 0777 ProlificUsbSerial # printf "\070\140\000\000" | dd bs=4 seek=2210 count=1 conv=notrunc of=ProlificUsbSerial # chmod 0555 ProlificUsbSerial # kextload -v /System/Library/Extensions/ProlificUsbSerial.kext # exit
If root access on your system is not enabled, look at the EnablingRootOnMacOSX page.