I have now updated the packet driver code for Western Digital Ethernet 
cards to handle the micro channel version WD8003ET/A. 

Also, if you have a WD8003EBT which has 32 kbyte, all of that memory is 
used - not just 8 kbyte (and the WD8003ET/A will use all its 16 kbyte).
The extra memory is used for the receive buffer chain, and if you have
HEAVY broadcast traffic you loose fewer Ethernet frames and can avoid a
noticable slow down in such cases. If you have light broadcast traffic
there is no change in speed.

I changed the interrupt level argument default from 2 to 3 so it is the
same as the default setting of delivered hardware.

The receive code is also somewhat simplified, e g counter interrupt is
not enabled and corresponding code removed (it didn't do anything useful).

There is now also a test if the memory range actually is available for the
WD8003E to use. Previously, if it was occupied the PC froze and had to be
rebooted.


TAIL.ASM needed changes to allow interrupt levels above 7 not just for
AT machines, but also for PS/2 with micro channel bus. Not to confuse, 
I made related changes also in HEAD.ASM.

There were no errorlevels defined and you could not test if a driver load
was successfull or not. In version 3.2e are now used some of the following
errorlevels:

;
; _____________________  0 = normal
; 			 1 = unsuitable memory address given; corrected
; In most cases every-	 2 = unsuitable IRQ level given; corrected
; thing should work as	 3 = unsuitable DMA channel given; corrected
; expected for lev 1-5	 4 = unsuitable IO addr given; corrected (only 1 card)
; _____________________	 5 = packet driver for this int # already loaded
; External errors, when	 6 = general cable failure (but pkt driver is loaded)
; corrected normal	 7 = network cable is open             -"-
; operation starts	 8 = network cable is shorted          -"-
; _____________________  9 = 
; Packet driver not	10 = usage message
; loaded. A new load	11 = arguments out of range
; attempt must be done	12 = unspecified device initialization error
;			13 = 
;			14 = suggested memory already occupied
;			15 = suggested IRQ already occupied
;			16 = suggested DMA channel already occupied
;			17 = could not find the network card at this IO address


This code is tested with all three card types (WD8003E, WD8003EBT and
WD8003ET/A) in PS/2-50 and PS/2-70 as well as different AT machines,
but only a few XT or the like is yet tested.
                                             
Jan Engvald, Lund University Computing Center
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