ACT apricot - Page 276

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INTRODUCTION
The Apricot's devices are contained in both the BIOS and
MS-DOS device lists. One example that has been seen
already is the MicroScreen, that is opened as a normal file
from within Basic in MS-DOS. The Apricot has many more
external hardware devices than most other machines, and
because of the way they are incorporated within the BIOS,
extra hardware systems can be accessed far more easily than
on other systems. In fact, the same routine can be used from
within a program to access everything from the Screen
Driver circuitry to the Mouse, and data can be passed both
to and from these devices.
At present, there are nine devices catered for within the
Device I/O handling, and more hardware and software
devices are
under development at ACT.
APPLICATIONS INTEREST
In the BIOS overview the "BIOS control device" was
mentioned. This is a routine which starts at 600H (within
the Pointer area) and can be called from an applications
program. Parameters are passed to either change the way
that the BIOS handles certain devices (such as the
communications ports) or access these devices for Input/
Output operations.
Calling
The Control Device
The routine requires (in all) three items of data to be
supplied
to it, and it returns one:
Parameters Supplied:
1. DEV -
Device Number
2. COM - Command
3. DA T - Data to be sent
Parameters Returned:
1. RET - Variable for Data/Status return