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DZ device driver for DECStation 2100, 3100, 5xxx

To: linux-mips <>
Subject: DZ device driver for DECStation 2100, 3100, 5xxx
From: "Olivier A. D. Lebaillif" <>
Date: Fri, 03 Jul 1998 16:52:17 +0000
Organization: IFR Systems, Inc.
Hi everybody,

I started to work on a device driver for DECStations to support the DZ
chipset not too long ago. I reached a point in the development where I
have a "working" base for my device driver but I would like to get
inputs from other developers on what direction to take for the support
of the DZ chipset.

The DZ chipset is a serial "controller" that provides 4 lines which are
used as follows on my DS3100 (and I guess on other models ?!?)

line 0: keyboard
line 1: mouse
line 2: "modem"
line 3: serial printer

all these lines are configurable as plain serial lines with a baud rate
up to 9600.  The "modem" line has some very limited support for a true
modem since it incorporates a DTR and DSR lines.

My questions are the following:
- Does it make sense to provide support for 4 serial TTY's ? Since it
complicates a lot the driver to manage lines that could be a TTY or a
keyboard for example.
- How much modem support should be incorporated since the maximum speed
is only 9600. I know I'll never plug a modem at the back of my DS3100.

My point of view is, and it's only mine, that's why I am asking for help
here :-)

I don't think anybody will unplug their mouse or keyboard to plug a
remote console instead (but I might be wrong).

The DZ device driver could offer:
+ two fully supported TTY's using the "modem" and printer lines
+ the serial printer support might be provided as well since it does not
complicate too much the driver.
+ a line dedicated for the keyboard only and one for the mouse only
(remote TTY's would not be supported on these lines).

that should give us something like:
/dev/lp or maybe /dev/slp       

Anyway, this is just a couple thoughts and I would like you to post or
email me any comments, suggestions, remarks, etc... Please voice your
opinions and if you feel like I am completely out of line... Hey
nobody's perfect, please let me know ;-)

That's all folks, thank you very much by advance.


Olivier A. D. Lebaillif
Design Engineer

IFR Systems, Inc.
10200 West York Street
Wichita, KS 67215-8999


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