Specifications
parameters you specify will
be
changed.
If
no parameters are included
on
the command line,
SETW
AIT
will provide a brief help screen.
If
the slash
(/)
is included,
SETW
AIT
will show
the new settings when it runs.
EXAMPLE
The
following SETWAIT command corresponds to the contents
of
the "TURBO.BAT"
fIle
on
the Little
Board/PC
Utilities diskette, and is recommended for systems which have all system
RAM
on-board, and which do not require slow
I/O
devices
on
the PC Expansion Bus:
SETWAIT UMB32
LMB5U
UMWO
MMWI
LMWI
10WI
RFWI
DMAWI
Alternatively, the software execution speed and bus timing
of
a
4.n
MHz
PC
can
be
simulat-
ed
by the using the following SETW
AIT
command, which corresponds to the contents
of
the
"SLOW.BAT"
fIle
on
the utilities diskette:
SETWAIT UMB32 LMB512 UMW2 MMW2 LMW2 IOW3 RFW2 DMAW3
THEORY
OF
OPERATION
SETW
AIT
allows you to control eight wait state options, which correspond to
the
parameters
controlled by the WCYI, WCY2, WMB, and
RFC
registers within the V40 microprocessor.
The V40's wait state control logic treats memory as three blocks, with
an
independent number
of
wait
states
used
for
each.
These
blocks
are
referred
to
as
"Low
Memory",
"Middle
Memory",
and
"Upper Memory", and the boundaries between them are dermed
by
two values,
"LMB"
and
"UMB". SETWAIT allows you to set these two boundaries, thereby derIDing the
three memory blocks.
For
example, the SETW
AIT
command
A>SETWAlT
UMB32
LMB5U<Returu>
dermes
Upper
Memory as the upper 32K bytes, Lower Memory as the lower 512K bytes, and
Middle Memory as that between these two blocks.
In
addition,
SETW
AlT
allows you to specify wait states for each memory block. Normally,
the Lower
Memory
and
Middle
Memory
blocks
are
occupied by
on-board
RAM,
and
the
Upper
Memory block is occupied by the on-board ROM-BIOS. Assuming this to
be
the case,
a typical system would
require
zero
wait
states
in
the
Upper
Memory
block,
and
one
wait
state
in
the
Middle
Memory
and
Lower
Memory
blocks. This can
be
set
by
the
following
SETW
AIT
command:
A>SETWAlT
VMWO
MMWI
LMWI<Return>
The
other three parameters which can
be
set by SETWAIT are the values for
I/O.
refresh,
and
DMA
wait states.
These
can
be
set individually, together,
or
at
the
same
time
the
memory boundary and wait state values are set.
For
exaDiple:
A>SETWAlT
10WI
DMAWI
RFWI<Return>
specifies one wait state for all
I/O,
DMA, and refresh cycles.
There are two restrictions regarding the use
of
the
I/O.
DMA, and refresh wait state parame-
SETWAIT-2