🚀 go-pugleaf

[ I wonder if the grue is a cousin to the line ea... ]

From all the pleas on the 'net lately, I am considering picking up my long
delayed project of working on a serial port expansion thing.  I lack
sufficient information on writing the device driver.  The last time I picked
up this project, I was stalled waiting for the mapper.device stuff to be
finalized.  I have decided to forge ahead and create an incompatible serial
expander, mostly because it won't autoconfig, and thus, must be MOUNTed...

The hardware is simple... plug a $20 PC/XT (or ESA, if you prefer) Serial
card from JameCo (with or without the $10 extra port option) into any
PC/XT bus adapter, such as the WEDGE.  This gives you the UART registers
sitting in a known place in memory.

The device driver is where I am a little confused.  I can easily write the
register twiddling, it is the DOS interface and overall design which
confuses me...

1)  What is the difference between a handler (as in port-handler) and a 
	device (as in serial.device)?  Which one (or both) will I want to
	write, to add the new device names COM1:, COM2: ...?

2)  Can I use Matt Dillon's generic DOS device, or must I wade through the
	RKM to pluck all the information myself?

I guess that question 1 is the more important.  I see little distinction
right now, but I surmise that there _must_ be some distinction, or there
would not be both types.  If I can get a skeletal structure, and a list of
the DOS packet type that a serial port must accept (that _should_ be in the
RKM), I can probably get a working driver banged out over Christmas break.

Am I missing something?  I am assuming that I will pass the address of the
UART registers to the device driver via the MASK MountList entry.  Is this
a no-no?  Is there a better way to do this?  All the driver should need
is the understanding designed in about the UART, and a base address of the
registers, passed at MOUNT time, and the MASK entry seems the easiest way
to pass a longword.

The sooner I get some information, the faster I can get this done and
into the world.

Thanks in advance,
-ethan




-- 
Ethan R. Dicks       | ######  This signifies that the poster is a member in
Software Results Corp|   ##    good sitting of Inertia House: Bodies at rest.
2887 Silver Drive    |   ##
Columbus OH    43211 | ######  "You get it, you're closer.