Re: broken Apple][ serial port

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <mattb-0611951845540001@crctestbnch.gi.alaska.edu>,
Dopey <mattb@gi.alaska.edu> wrote:
> In article <8B4306E.009E0009E7.uuout@genesis8.frmug.fr.net>,
> ludovic.lange@genesis8.frmug.fr.net (LUDOVIC LANGE) wrote:
>  
> > That's why I am asking : Does anybody have a technical
> > documentation on the Apple II (c or e), of its mother board,
> > serial interface, serial port pinout, etc...
> 
> The pinouts are:
> 
> 1  DTR
> 2  TD
> 3  GND
> 4  RD
> 5  DSR

Note that the above is the pinout for the IIc.  The IIe (with a Super
Serial Card) uses a DB-25 female connector, wired as a DCE or DTE
according to the direction of the MODEM/TERMINAL jumper block
(pointing to MODEM for DTE pinout, pointing to TERMINAL for DCE
pinout).  The direction of the arrow indicates the device that is
supposed to be connected via a straight-through cable.

> It is all controlled by the IWEM chip and has two buffers, one for
> each port. 

Pardon?  "IWEM" is the ImageWriter emulator for the LaserWriter, which
is a PostScript program.  :-)

If you mean "IWM" (Integrated Woz Machine"), which is a chip in the
IIc, then you are very wrong.  The IWM is the disk controller.

The IIc serial ports are controlled by the two 6551 ACIA chips (one
for each port).  A few RS-232 buffering chips are used to connect the
ACIA chips to the serial ports.  Some of the flow control lines on the
6551s are used to control/monitor other devices in the IIc.

> The way you can set the port to different databits and speeds is by using
> the Apple //c System Utilities disk.  It allows you to set the ports for
> different rates, bits, parity, etc.

This sets the default values for subsequent programs that use the
firmware (and don't override the settings).  Most communications
programs bypass the firmware and communicate directly with the 6551's.
These programs have their own settings for baud rate, etc.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand