17 Jan
2003
17 Jan
'03
9:33 a.m.
Hi again folks,
Thinking about the VS3100/VT1300/VXT matters brought up another question that
has nagged me for a while. How much compatibility is there between KA410
(VS2000), KA42 (VS3100 M30/38/40/48), and KA43 (VS3100 M76) as far as video
boards go? I mean GPX and SPX. (Were there others?)
I know that the 4-plane and 8-plane GPX boards were originally designed for
VS2K, and I'm pretty sure that the VS3100 ones are the same as the VS2000 ones,
which implies that the video option connector on KA42 has to be identical to
the one on KA410.
But now comes SPX. I have seen many VS3100 M76 SPX machines, and SPX appears to
have been pretty standard on these machines. But I have questions. Does the SPX
board also work on earlier VS3100s and on VS2000? I seem to recall from
somewhere that the answer is yes for VS3100 and no for VS2000. Could someone
confirm? And how about the other way around? Can M76 use GPX? No video option
at all? (I seem to recall that base mono video was removed on KA43.)
This makes me wonder about the nature of interface between the system board and
the video option. Since it originates from VS2K, common sense says that it has
to be 16-bit EDAL, since that's all VS2K had. But then there is the DTJ article
about the design of VS4000 M90 where they've used a version of SPX that
attaches directly to 32-bit CDAL. Furthermore, they just lifted their SPX
design from the VXT2000 where it also attached directly to CDAL. Hmm. Did the
original SPX used in all these VS3100 M76s also attach to CDAL? Then how can
the video option connector, which at least mechanically hasn't changed since
KA410, be sometimes EDAL and at other times CDAL? Were there a lot of unused
pins on the original KA410 connector that were made into upper 16 bits which
are used sometimes but not at other times? But then if turning CDAL into EDAL
were only a matter of using only lower 16 bits, why did they design a much more
complex chip (SEAC) for this very purpose in VS4000 M90 (see the DTJ article)?
Just a hardware-minded hacker being curious.
MS
17 Jan
17 Jan
10:45 a.m.
Thinking about the VS3100/VT1300/VXT matters brought
up
another question that has nagged me for a while. How much
compatibility is there between KA410 (VS2000), KA42 (VS3100
M30/38/40/48), and KA43 (VS3100 M76) as far as video boards
go? I mean GPX and SPX. (Were there others?)
That's the lot (at least for KA42/KA43 - the later VS4K series
had further developments of the SPX available at least).
I know that the 4-plane and 8-plane GPX boards were
originally designed for VS2K, and I'm pretty sure that the
VS3100 ones are the same as the VS2000 ones, which implies
that the video option connector on KA42 has to be identical
to the one on KA410.
I think the origins of the GPX go back to the QDSS Q-bus
board set as used in the VAXstation II (the "Dragon" chipset).
I don't know whether that was itself derived from the QVSS
original monochrome Q-bus graphics.
But now comes SPX. I have seen many VS3100 M76 SPX
machines,
and SPX appears to have been pretty standard on these
machines. But I have questions. Does the SPX board also work
on earlier VS3100s and on VS2000? I seem to recall from
somewhere that the answer is yes for VS3100 and no for
VS2000.
My recollection is that the same GPX board was indeed used on
the KA410 and KA42s. That was the VS40X-MA.
Could someone confirm? And how about the other
way
around? Can M76 use GPX? No video option at all? (I seem to
recall that base mono video was removed on KA43.)
I'm pretty sure that a VS3100-76 with no graphics board *will*
come up using onboard monochrome (use the green signal).
I don't think I've ever actually used one this way, but I do
know that the GPX and SPX options came with a little stick-on
panel that said either "GPX" or "SPX" in about the right size
and font to stick right after the "VAXstation 3100 M76" nameplate.
This makes me wonder about the nature of interface
between
the system board and the video option. Since it originates
from VS2K, common sense says that it has to be 16-bit EDAL,
since that's all VS2K had. But then there is the DTJ article
The VS2K tech manual describes the interface there and
the connector pins etc. are all in there.
about the design of VS4000 M90 where they've used
a version
of SPX that attaches directly to 32-bit CDAL. Furthermore,
they just lifted their SPX design from the VXT2000 where it
also attached directly to CDAL. Hmm. Did the original SPX
used in all these VS3100 M76s also attach to CDAL? Then how
I *think* that in the KA42 systems, they converted from CDAL
to EDAL (or whatever) as necessary. The KA43 was a Rigel chip
shoe-horned into a CVAX system, so they did something to
convert the Rigel bus (RDAL?) to CDAL and then left as much
of the rest of the box alone (I don't have the KA43 stuff
to hand so I may be misremembering the exact details here).
In the VS4000-90, the NCA is (IIRC) an NDAL-to-CDAL bridge.
Then the EDAL hangs off the CDAL to give access to some of the
internal options that presumably were leveraged from earlier
CVAX designs (KA42 etc.). But the graphics hang off the CDAL.
As you note, these are *not* the standard SPX etc. but designs
that presumably had already been modified from the original
SPX to remove the EDAQL interface and use CDAL instead (to
more closely match the VXT requirements ... I'm guessing, I
cannot find the article I'm sure I've read that describes
the development of the VXT2000).
Antonio
--
---------------
Antonio Carlini arcarlini(a)iee.org
18 Jan
18 Jan
9:22 p.m.
I'm pretty sure that a VS3100-76 with no graphics board *will* come up
using onboard monochrome (use the green signal).
I don't think I've ever actually used one this way, but I do
know that the GPX and SPX options came with a little stick-on
panel that said either "GPX" or "SPX" in about the right size
and font to stick right after the "VAXstation 3100 M76" nameplate.
Mine does and it is just a matter on which pin you pick it up in the
back of the box! I'd have to go to my office to ck it again.
Fred
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