.TH XQVSS 8 "3 January 1985" "X Version 10"
.SH NAME
Xqvss - X window system QVSS implementation notes
.SH DESCRIPTION
.PP
The QVSS hardware in the DEC VS1 and VS2 is monochrome.
The usable size is 864 lines by 960 pixels/line.
(Future driver mods will default to 1024 pixels/line on the VR260 monitor
of the VS2, in Ultrix 1.2; for VR260 monitors under 1.1, patch
the kernel variable qv_def_scrn to 2.).
.PP
Probably the most irritating problem with the QVSS hardware is the
cursor support, which is limited to 16x16.
As only ``and'' and ``or'' operations are available in the hardware,
the driver inverts the cursor depending upon the pixels below
the cursor.
We will eventually get fed up and implement a software cursor.
.PP
Under Ultrix-32 release 1.1 and 4.2BSD,
the window system will be slightly unreliable due
to a kernel problem.
Fixed in Ultrix32 release 1.2.
Under Ultrix-32 1.1, your best bet is to use unix domain connections
(unix:0 as host spec's) for local connections.
.PP
Thanks must go to Dave Carver (and others) in the DEC Workstations
group for implementing the bit-blit library.
Large area bit-blit code is compiled on the fly and runs at optimal
speed.
.PP
Performance is now tolerable, between 3400 and 4200 characters/second
on a VS2.
Performance on a VS1 is approximately 2000 characters/second.
Some further improvement can be expected.
.SH "SEE ALSO"
X(8c), X(1)
.br
`Xlib - C Language X Interface'
.br
`ddX - Device Dependent X Interface'
.SH AUTHOR
.br
Copyright (c) 1984, 1985, 1986 by Massachusetts Institute of Technology.
.br
See X(1) for a complete Copyright notice.