SOFTWARE
As a
command
is
issued
by MS-DOS for
the
Bios
to
print
a
character
on
a
connected
line
printer,
the
Bios
will
place
this
character
in
a 2K buffer,
and
returns
control back to
MS-DOS
immediately.
When
the
lines from
the
printer
state
that
it
is ready for
another
character,
the
next
entry
in
the
buffer is
sent
to
the
printer
to be
printed
and
room
is
made
in
the
buffer for
another
character.
3. Communications buffer.
The
communications
buffer·
allows
high
speed transfer (up
to
9.6 kbaud) of
data
between
the
Apricot
and
other
computers.
The
serial driver supports
full
XON
/XOFF protocol
to
prevent
the
loss of
data
when
the
buffer fills.
Apricot Control
Device
This
is a software device
which
enables
the
programmer
to
pass
parameters
to
routines
in
the
BIOS
for controlling
various hardware
and
software functions
without
having
to
resort
to
assembly
language programming. As a
result
no
low-level hardware knowledge of
the
Apricot is required by
applications programmers.
System Configuration Block
The
system
configuration
block
is
a
small
block of
memory
which
contains
the
reference values
that
the
BIOS
uses for
port
characteristics, character sets
and
keyboard
tables.
By
changing
certain
parts
of
this
area
it
becomes easy
for
the
programmer
to
change
the
hardware
and
software
configuration of
the
Apricot.
MicroScreen driver
A
simple
method
of
controlling
the
MicroScreen
has
been
devised whereby
it
is
consistent
with
the
standard Apricot
(Sirius compatible) screen.
The
Escape sequences
utilised
on
the
large Apricot
screen
are
the
same
as
on
the
MicroScreen,
for example,
the
clear
screen
command
is
the
same
as
on
the
large screen.
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