Specifications

7.8 VS100 STATUS REGISTER
Here is a ma~ of the VS100 read-onl~ status reSister:
bit
•
7
6 5 4
3
2 1
0
I
1
I
1
I
,-----
ManlJfacturing
Mode
(0
=
~es,
1
=
no)
1
I
I
I
'--_ .....
BBA
Present
(0
=
'::f.es,
1
=
no)
I I I
I
\-_ .... ---
NXM
(0
=
no,
1
=
~es)
I
t I
\_----
RetrY_Overflow
(0
=
no,
1
=
~es)
I
I
\ ..... __ ...
Link_Available
(0
=
no,
1
=
~es)
I
I
' .. __ .......
Left HOIJse
Button
(0
=
'!:Ies,
1
=
no)
t
'-----
Centre
Mouse Button
(0
=
'::Ies,
1
=
no)
,-----
Right
MOIJse
BIJtton
(0
=
'!:Ies,
1
=
no)
Manufacturins Mode is set when the host is performing an electrical
loop-back on the fibre link at its own end. NXM is set when non-existant
UBW memor~ is accessed from the 68000. If non-existant UBW memor~ is
accessed from the BBA, a leve17 interrupt is Senerated instead. The 68000
generates a bus error when NXM is set, and it is the dut'!:l of the microcode
to examine this register in the bus error routine to determine the nature
of the bus error.
House buttons Senerate a zero code when de~ressed, but
their status bits otherwise remain hiSh. Link_Available True means that
the LED is lit at the UBW end of the fibre link.