RE: Mark IV Electronics Design

["Griffing, Dan" <DAN.GRIFFING@kla-tencor.com>]

Tom & Chris

Thursday, January 08, 1998 7:21 PM
Tom Droege wrote:
	>As outlined some time ago, this has long been done.  The
problem was
	>to design an interface that was data push.  The receiving end
has no 
	>control.  I did not want the read out from the chip to vary in
speed as
	>would be the case with any computer interface.  i.e. from time
to time
	>the computer wants the interface and holds things up.  So the
design
	>is a straight byte parallel interface designed to go at up to a
20 MB or
	>so rate (for a short cable).  So it is not any standard
interface.

	At 05:27 PM 1/8/98 -0800, you wrote:
	>Tom Droege wrote:
	>> 
	>> This is mostly a reply to Grzegorz Pojmanski who is
interested in using the
	>> Mark IV electronics.  I am posting it to the group as there
may be general
	>> interest.   The status today is that there are rough drawings
for
	everything.
	>> The connector details have not been worked out. 
	>
	>If you have not yet worked out the cable that feeds the
	>memory board would you make it look like a printer
	>interface.  Modern printer ports are bi-directional
	>and very fast. (Just look at what a ZIP drive can do.) 
	>If camera data could look like data comming
	>back from a printer (or parallel interface ZIP drive)
	>then at some point down the line
	>we could just pull the memory card and plug the cable
	>into an EPP printer port.  You've likely got the required
	>signals already. Likely just need to get the pinout
	>correct.  I think it is simple: ready, ack, and data. 
	>One advantage of dropping the card is cost, but also, the
	>PC gains access to the pixels quicker by several tens
	>of seconds.  May help when you are tring to focus.
	>
	>I think the new ports bypass the ISA buss which should
	>help, but also you don't need to write software to read
	>from a standard port.
	>
	>Any rate if you copy the printer port pinout someone can
	>experiment later.
	>
	>
	>--Chris Albertson
	>
	>  chris@topdog.logicon.com                Voice:  818-351-0089
X127
	>  Logicon RDA, Pasadena California          Fax:  818-351-0699
	>
	>

Why not use a high speed LAN interface?  
Then any one of a wide range computers
with different speeds and operating systems 
with standardized LAN hardware and low level 
vendor-supplied drivers could interface to your
system.  Alternatively, because Intel Pentium
PC compatible computers are dirt cheap, you
could make an entire Mark IV server with a 
LAN interface.  

You could go ISA parallel to the PC server with 
standard off-the-shelf interface cards and this 
wouldn't be a problem since the Mark IV would 
include the entire server.  Server software would 
allow internet connections or other client computers 
on a LAN to connect and run the system.  
Window 95 and NT have a DCOM (Distributed 
Component Object Technology)  software 
technology which allows distributed computing
so that the Mark IV telescopes can be remotely 
controlled over the network and even over internet.

With DCOM, you could easily have completely 
remote observation sites with the ability to make
unattended observations.

Dan Griffing
Staff Software Engineer,
KLA-Tencor