long DMA's and Photometrics CCD camera

[Dan Ts'o]

x
	Thanks for the replies to my recent request for CCD camera info. We
have ordered a Photometrics CCD camera (Thomson CSF chip) and controller.
We would like to ask two things now:

	1) Has anyone used this camera controller with a DEC computer ? We
plan to use it with a MVAX II running Ultrix 1.2. Any drivers or software
out there ? (I am aware that Photometrics can supply software for a 68000
UNIX box, how easy would this be to port ?)

	2) In some applications it would be useful to perform LONG DMA's,
in excess of 200,000 words. All DEC DMA controllers I am aware of have
a 65K DMA length limitation. Has anyone performed longer DMA's ? What are
the ULTRIX/4.2BSD implications of 200K word DMA's (memory maps, etc.) ?
Any hardware controllers available to handle these long DMA's ? The Photometric
controller is designed to interface a standard DEC DR-11W.

	One possibility is that Grant Technologies makes a DRV-11W like card
which has an on board FIFO. It might be possible to issue multiple DMA
requests and not drop data but buffer it in the FIFO.

	Another possibility is to use two DRV-11W's and some external logic
to switch between the two controllers as each controller's word count is
satisfied.

	Anyone play games like those above ?

	Thanks.

					Cheers,
					Dan Ts'o
					Dept. Neurobiology
					Rockefeller Univ.
					1230 York Ave.
					NY, NY 10021
					212-570-7671
					...cmcl2!rna!dan
					rna!dan at cmcl2.arpa

P.S. For those interested, the Photometric CCD camera was the most reasonably
priced camera to provide CCD features, square arrays, 12bit grey scale and
flexible readout (at $20000). Princeton Instruments also had one that was
similar but less flexible and tied to an IBM PC (or was it Princeton
Scientific). Microtex had a faster A/D readout but wanted $120,000
(including MVAX II). No other companies were found (I talked to Eikonics,
Spin Physics, ITT, Reticon, Princeton Applied Resarch, Scantech)