[Xitami] devices problem

[Paul Reid]

> What is aux anyway? 

In CP/M (before MS-DOS), the devices were CON, PRN, PUN, and AUX. 

CON was (still is) the CONsole: display and keyboard, teletype or
CRT. 

PRN is a printer, and generally Serial (but not always RS-232!)

PUN is the paper-tape punch, to save data on. (I can't remember
if you read tape on the same port or if there was another, RDR?)

AUX was basically "extra", like spare inputs on the back of a
hi-fi amplifier. Usually AUX pointed to the serial port driver. 

IBM had CP/M in mind when they made the IBM PC. The first O/S for
the PC was that thing Gates bought and modified, which IBM sold
as IBM PC-DOS. But IBM had mapped out multiple serial ports and
adopted a parallel interface for the Epson printer they were
re-badging. So the ports had to have more names to cover all the
new possibilities. LPT1 LPT2 LPT3 (and LPT4 on PS/2 BIOS) denote
the parallel ports. For back-compatability, by default PRN points
to the same routine as LPT1. 

A fully IBM compatible PC has a display much faster than any
serial port, and CON defaults there. However you can re-map CON
to a serial port and there is even a utility to do so. I once had
an Intel-made 286 that would run DOS but was -not- IBM PC
compatible: no internal video. On that beast, CON defaulted to
one of the serial ports and DOS and WordStar ran on a terminal. 

There are a LOT of reserved device names in this tradition.
MS-DOS 2+ has CLOCK (or CLOCK$$). And let us not forget NUL.
Win95/WinNT extend this by giving "LPT1.DOS" a special meaning:
much like "LPT1" but not quite. 

 -PRR