Installable Drivers 1 - Tandy 600 Programmer's Reference Manual

Installable
Drivers
The
Hand-Held
software
will
support
a
limited
form
of
installable
device drivers.
These device
drivers
will
be
small
machine code programs which
will
be
contained
in files
within the
file
system
of
the
Hand-Held
computer.
The
user
will
be able
to install
a
particular
file
as a driver
for
a particular
device.
When
installed,
the driver
program
will
be placed
in
a protected
memory
location
by the
Hand-Held O/S,
and the appropriate interrupt
vectors
will
be changed
to
point
to
the installed driver.
The
driver
program must
then provide support
for
all
specified
BIOS
functions
for
the given device.
As
an example, an
installed driver
may
be used
to
perform
special
character
code
translation for
a
different printer
than the
one
supported
in
the
BIOS
printer driver
code.
It
would be possible
to
configure the
Hand-Held computer
to
support
different printers
by providing
an
installable driver for
each
printer.
This
mechanism
does not provide
for
the
inclusion
of
new
devices not already described
in
this
document.
It
allows the
replacement
of
the
BIOS code
to
handle
a
specific
type
of
device
with
new
code
to
handle
that
same
type
of
device.
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