M.I.5¾ wrote:

> I have not found any RS-232 device that fails to work with a USB to RS-232
> adapter. All the RS-232 handshaking signals are fully supported. They even
> work with DOS type applications through the command prompt without any
> problems. PC cards no more have the proper chip than USB devices (the
> UART's functions are built into a larger chip in both cases).

The UART in the PC Card sits almost directly on the ISA bus, without the
intervening USB converter.

The problem is more in other operating systems such as Linux.

One place I worked we had a device for JTAG and BDM debugging that
required a parallel port interface. You could use it with a CardBus to
parallel port adapter, but not a USB to parallel port adapter. It was a
pain not to have a parallel port on the notebook because the adapters
cost around $100.