SGA_EMUL(1) — USER COMMANDS
NAME
sga_emul − access graphics board in compatibility mode
SYNOPSIS
sga_emul [ −f frame-buffer ] command
DESCRIPTION
sga_emul causes a process and all processes exec-ed from it to access the SGA20 graphics board in compatibility mode, that is, as a simple 1152 x 900 color frame buffer without any of the accelerating features of the SGA20. sga_emul is needed for running certain old commands that require a specific kind of frame buffer, but don’t take frame buffer arguments.
The default value for the frame buffer argument is /dev/sga10, which is a pseudo-device which treats the SGA20 like a CG4. Note that the SGA20 does not have overlay planes; if the SGA20 should emulate a CG3 instead (a CG3 is a CG4 without overlay planes), then the user should specify a frame buffer argument of /dev/sga0.
If there are multiple SGA20s, then commands can be made to run on any of these devices in compatibility mode by specifying /dev/sga10, /dev/sga11, or /dev/sga12 to emulate a CG4, and by specifying /dev/sga0, /dev/sga1, or /dev/sga2 to emulate a CG3. These pseudo-devices are mapped to the physical slots in the order in which the boards were first found by the operating system. The command dmesg(8) will display that order. If the system has a /dev/sga2∗ then it will appear in the dmesg output as a device that has been probed. If there are multiple /dev/sga2∗ then the order in which they appear in the dmesg output file is the order in which they are called /dev/sga20, /dev/sga21, and /dev/sga22 by the kernel. Those same devices can be run in compatibility mode, emulating a CG3 (/dev/sga0, /dev/sga1, /dev/sga2) or a CG4 (/dev/sga10, /dev/sga11, /dev/sga12).
Access of the SGA20 in compatibility mode will only occur for the life of the executed process. If the command forks a process, that sub-process will attempt to access the SGA20 in native mode.
Opening these pseudo-devices causes the commands to run without graphics acceleration. The pseudo-devices are not intended to be used except with this command.
EXAMPLE
The following sga_emul call:
example% sga_emul solcube
will run the old Core library demo, solcube, accessing the SGA20 strictly as a CG4.
SEE ALSO
Solbourne Computer, Inc. — 10 Dec 1990