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<title> OS/A65 Device Drivers </title>
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<p><h1 align=center> OS/A65 Device Drivers </h1></p>
<p> <h2 align=center> (c) 1989-96 Andre Fachat </h2></p>
<hr><p>
This file gives a description of the so far implemented device drivers
for OS/A65.
<h4>video Device</h4>
The video device incorporates not only one but four devices, video1-video4
(with 2MHz, only 2 devices are working).
As hardware it needs the video card and the keyboard card with a CBM 3032
keyboard attached to it. If available,
the piezo beeper on the IEEE488 card is used to generate bell signals.
<br> The video card has one video port only, so the video is shared
between the four possible video devices. The "@" key is used to switch between
the different terminals. As there is no way to send some kind of ioctl
message along a stream, this key has some more functions:
with Control (RVS/OFF key on CBM 3032 keyboard), the key closes the stream
from the sender side, thus signaling an EOF. With control and shift,
the the device is switched between the two modes.
<ol>
<li> <strong>indirect mode</strong>: keyboard events are printed on the
screen only, not sent to the stream. If a Return occurs, the actual
line is sent to the stream. This is default.
<li> <strong>direct mode</strong>: all keyboard events are directly
passed to the stream.
</ol>
Supported terminal control codes are Bell, Backspace, Carriage Return,
Line Feed and Form Feed.
<h4>par Device</h4>
This device handles the (simple) centronics port on the shugart bus
board.
<h4>nuldev Device</h4>
This device reads a given stream until end, i.e. EOF and then closes
the stream. Like /dev/null for writing. You cannot read from it. Only
a certain number of streams can be handled before an error is returned
on open.
<h4>spooler Device</h4>
This is a kind of serializer. You can copy one file after the other
to this device, even if the first files are not yet through. When copying
the output of the spooler to another file, e.g. the spooler
device, they appear in the same order as copied into and intact, i.e.
the files are not mixed.
<h4>ser Device</h4>
Ser stands for serial device and that's what it's doing. It handles the
two serial device ACIAs on the BIOS and on the keyboard board of the CS/A65
computer. There are
some watch outs, though. From the serial device, only RTS/CTS are handled.
A low on an incoming /RTS stops sending. If the stream to write the data
to is above the high water mark (3/4 fifo size), then /CTS is set low.
After the stream going below the low water mark (1/4 fifo size), /CTS
is set high again.<br>
With DC_SPEED, the baud rate of the device can be set:
<pre>
parameter (y) speed (baud)
-------------------------------
1 50
2 75
3 109.92
4 134.58
5 150
6 300
7 600
8 1200
9 1800
10 2400
11 3600
12 4800
13 7200
14 9600
15 19200
</pre>
With version 1.3.10 we now also have driver for an UART 16550A, with 16
byte builtin FIFO (oa1ds3.a65). There also is a RS232 driver for the
fast RS232 interface for the C64 by Daniel Dallmann, as
described on his homepage or in the comp.sys.cbm FAQ.
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