OS/A65 Device Drivers

(c) 1989-96 Andre Fachat

This file gives a description of the so far implemented device drivers for OS/A65.

video Device

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.
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.
  1. indirect mode: 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.
  2. direct mode: all keyboard events are directly passed to the stream.
Supported terminal control codes are Bell, Backspace, Carriage Return, Line Feed and Form Feed.

par Device

This device handles the (simple) centronics port on the shugart bus board.

nuldev Device

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.

spooler Device

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.

ser Device

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. 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.
With DC_SPEED, the baud rate of the device can be set: 
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
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 by Daniel Dallmann, as described on his homepage or in the comp.sys.cbm FAQ.