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ll>t:
data phase is followed by the SU.tu
~
in which the player
rc1ums
a
single byte to tle host computer indka1ing the
success
or
railure ol the
command.
In the lauer case, the
host
computer may
be
ab&c
10 ask. the player for funher informalion with
a
ttq11tSt
~
command
to
determine
what has
cone
wrona.
Finally,
1he player sends
a
c:o•-d
cv•ph1•
~
10 the hos1
compu1er before rcleasin! the SCSI
bus.
This is required by 1he SCSI
standud, bu1 serves no purpose for LY-DOS as all operations arc
synchronous
(i.e.
oomplele before the status is returned).
VP41Sisaes
The VP41S SCSI interfae< adheres strictly
10
SCSI spearications for
both hardware
and
software. The bus cable is dat!>y-chained in single
ended
mode;
parity is ignored. The connecto, pin TERMPWR is not
connected to an internal power supply.
L V-DOS suppons
all
SCSI bus phases e1tcep( the optional Reselection
phase and Message Out phase, and suppons
arbi1ary
systems with
mulliple
initiators.
The
·~ard
resef condition is
suP90ned
by LV•
DOS.
As~nchronous
transfer mode is the
default; optional
synchronous
trander modt
and linked
commands
a,e
not
supponed.
01te ol 1he
values
specified in the oommand
dCKriplor
block
is the
1..oJic Unit Number (0 -
7).
This
is provided by 1he SCSI s1andud to
addr~s diHerent logic units within the same
device.
In !he
case
of L V-
DOS.
the \Dgie unit number is used tospecifywhich
oflhe volumes
is to
be Kcei;sed by the current command (rather like specifying
one
of two
or
more floppy drive:. attached to the same
controller).
Logic unit 7 is
used
fOf
all
commands notpenaining to a panicutar
volume,
including
reading
the
volume directory. A logic unit number
is
ass.igned
to
a
volume
when
it is opened.
DEFAULT
CONDITIONS
Def.-AMt•DpC'OndhioN
Al powcr•up
or
reset thi.' system is in the
standby
conditiofl. To log 1he
disoconto
LV-DOS.
an
initial Start-unit
oom111and should
be issued
10
the
pfayu
be-fore
any
ot her
SCSI
command.
If,
howl'vet,
lhl'
first
command afler
a
hard
reset
is
a
Read
oom111and, lhen the
Stan-unit
furtt1ion is
11utomatkally
perfonnl'd
prior to
1he
read
action.
After
a
successful
execution of the
Start-uni! command
the
player will
have a start-up default mode
as
follows:
Audiooff
Remote
control handset on
lndndisplayoff
Nonnal video on
VideomodeVP3
Front panel
controls enabled
Search
mode
R I
In
IKklition.
F-cocle
commands
issued to
logic
unit 7 will
bt
e:,;ccutcd
rully
lransparenl and
F-code
commands
is.~lH:d IOol~r
logk
units
will
apply to
1he
volume
associated
to that logic
uni1.
If
lhe
disc:
has
no
digital
data
,
such
as
a
Cl V
or
C
AV bul
without
data,
o,
if lhc
e11ccution
of
the automatic
Stan-unit command
fails for
any
r,:non, lhen the
player
will
be
reset to 1he
de[ault
conditions
(according
to
the
F-code
specifications)
and
fully
uansparcnt
F-codc
control
is
possible
via all logic units. It
is
the respon~ibility of the
inilialor
to select
lhe desired player
mode
fo, the particular
application.
See 'Mode
selection' in Section 4.
If
11te ~an-unit
command
is given
via
SCSI,
the
video
mode
will be
VPl
even if 1he command fails. Thi~ enables 1he
host
eomputet 10
displayanerrormes.nge.
A Stop-unit command from the initiator is received as
an
·unload'
command
at
the VP415, and all switches are reset to lheirdefaulc
values
(see F-<Ode
oomrnand
·Reset to default'). It
is
the
responsibility
of
the
initiator 10
send
an Ejcc1 command if
necessary.
After
a Stop-unit
oommand, all
1he
volumes
are
dosed:
a subsequent
Stan-unit
command
is
needed
to open the volume!
again.
L \'-DOS COMMA!'IIDS
LV-DOS
suppons:
all mandatory commands for read-only
dire<:!·
aco:<55
devices.
some extended commands, and some vendor-unique
commands. II should
be
noted that !he SCSI command aod reP'y
formats supported by LV-DOS are a subset of the general SCSI
definition (ANSI
siandard XJT9.2).
The first field in
the
command descriptor block is
a
po~
co4c (value
0 -
7). The
groupoode
defines the fonnat or the rest of the
command.
LV-DOSsuppons
GroupOcommandsforreadingdiscdata andGmup
6
(vendor-uniqu.e)
commands
for F-code read/write commands.
A
single status
byle
is
returned
10
the
host
oomputer on
oompl,elion ol
a
command.
The
SCSI
standard
as.!.igns
meanings
to
each bil
in this
byte, of which L V-DOS uses the following subset:
bitO
reserved.O
bit I
oommandfailed.checksensestatus
bit2-7
resoerved.O
A
return value
of
O indicates that the command was
succt;ssful.
If
a
non-zero value
t!,
returned, the host computer should use !he
RelljM!t
• - command fo, more details o[ whal went wrong.
Cro•p0(6-ltyec)~
The
fonnat
o(
a
G,oup O
command descriptor
block
is
as
follOW$:
(MSbi1)
(LS
bit)
Byte
O
Groupoode(O)
Command code
Logk unit number
logicalblockaddress(MSB)
Logkal
btock address
logical block address (LSB)
No.oldatablockstolransfer(transferlength)
Con1rolby1e(O)
The
group
code
+
!he
command code
together
form
the
operalion
code.
The
logical
block
address parameter
bytes
apply
only
lo
Read and
Write
bl011:k
cOll\mands. For
other
commands
they are in general
meaningless
and
should
be
sel
to zero
unless
otherwise
stated
.
The vendor-unique
bits, reserved bits. flag bit and link bit in 1hecon1rol
byte arc
not
Mipponed
and should be set to zero.
There is
no._.
ia
or
daall
0111
phase unless otherwise
s1a1ed.
J8
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