ACT apricot - Page 308

GSXSYSTEM
What is Graphics Systems Extension?
Each graphics device is
mechanically and electrically
different,
and requires a special program to run it. This
program is called a Device Driver. Graphics Systems
Extension consists of a Device Driver written by ACT
(called the GIOS - or Graphics Input/Output System) and a
User Interface supplied by Digital Research called the
GDOS (Graphics Device Operating System).
For details on how to install Graphics Systems Extension
and the relevant program functions to use it, see the GSX -86
Programmer's manual.
SYSTEMS INTEREST
The Graphics Systems Extension Apricot Graphics
Device driver
consists of three files:
1- GRAPHICS.EXE
2-ASSIGN.SYS
3 - DDACRT.SYS
1.
GRAPHICS.EXE
This is the file which contains the Digital Research
GDOS module. When loaded, it will first allocate about 32K
of
user RAM for itself and the GIOS. Then it will open
ASSIGN. SYS and read the Device number and the name of
the file containing the GIOS device driver from it. After
doing
this it will open the GIOS file and load it into RAM so
that it is within the 32K that GDOS has allocated. Interrupt
223 is set up to point to the GDOS command structure
entry point, then the program terminates with an MS-DOS
"Stay Resident" call thus moving the start of the TPA up by
32K.