ISV(4) | Device Drivers Manual | ISV(4) |
isv
— IDEC
Supervision/16 image capture board
isv0 at isa? port 0x2f0
isv0 at isa? port 0x2e0
isv0 at isa? port 0x3f0
isv0 at isa? port 0x3e0
isv
is a driver for the IDEC
Supervision/16, an image capture board that plugs into a 16-bit ISA bus. The
IDEC Supervision/16 digitizes an NTSC television signal, storing a 512 x
480-pixel, 8-bit grayscale image in its 256kB dynamic RAM array every 1/30th
of a second. The host reads frames from the DRAM using 122881 16-bit I/O
reads. Reading frames from the Supervision/16 is quite slow: after the host
reads a 16-bit word from the DRAM, the Supervision/16 state machine takes
approximately 0.5 microseconds to get ready for the next read.
Theoretically, a frame rate of approximately 10 frames per second is
possible. isv
achieves a frame rate of approximately
6 frames per second.
Programming the Supervision/16 Image Capture Board, IDEC, circa 1991.
The isv
device first appeared in
NetBSD 5.0.
The isv
driver was written by
David Young
<dyoung@NetBSD.org>.
Synchronizing with the hardware and reading frames from it is very CPU-intensive.
isv
will not detect the capture board if
it is not attached to an active video source. To force
NetBSD to detect the capture board at any time,
re-scan the ISA bus using, e.g., drvctl
-r
isa0.
April 1, 2008 | NetBSD 10.99 |