Yeah, Exchange is a good comparator because it shows what the mail aspect of Notes might have been like had it been designed in the mid 90s rather than the late 80s.
It's hard now to appreciate how different corporate IT was from the free-wheeling Internet world. The unexpected popularity of the web really did change everything.
Systems Concepts may have had other prospects, but they had so much trouble getting the product out the door that Compuserve ultimately helped them finish it, licensed it (? exclusively), and produced all but a couple of the machines that went into production. I found a microcode bug in one of the first SC-built machines that caused the string-comparison instruction to return true whether or not; Gary Brown took that to SC and reported their reaction as "Damn, you caught us!", and that was kind of the end of that. You might have some stories to tell of the flight from X.25...?
I am from a place where CompuServe was just something you read about the way you read travelogues or otherwise reports from far away country, unfortunately.
I encountered data about System Concepts due to being interested in PDP-10 history and so on.
It was one of multiple successors to PDP-10 that tried to capitalize on existing user base after Digital decided to utterly cancel all 36bit work in favour of VAX (legends claim the last prototype ended up in millpond).
Some started even earlier, trying to compete on speed or other attributes (like Foonly)
System Concepts is the ones who ended up with CompuServe as client/effective owner from my memory. XKL was somewhat successful to the point they are the reason why last known PDP-10 was made after closure of last VAX manufacturing line, but nearly all of their systems was for internal use in their network gear
There were options for migrating from PDP-11, not PDP-10.
PDP-11 was a 16bit byte-addressable minicomputer that was extended to 22 bit physical addresses through MMU. VAX took PDP-11 and extended it into 32bit flat addressable paged system.
PDP-10 was 36-bit, word-addressed with 18bit addressing (plus segment extensions in KL-B that were only really implemented in 3rd party follow-ons, a mainframe-in-all-but-name.
VAX would mean starting from zero unless nearly everything was written very high-level, which is doubtful given the optimizations needed to run so many simultaneous users.
It had more to do with the ecosystems and the corporate relationship. The -10s came from a earlier perspective. It was open source before "open source". You bought the software and you got the source, because of course you did, you couldn't even install it otherwise. Compuserve tracked TOPS-10 up to version 6.01, with their own additions and patches: far-reaching but well encapsulated. They could not track 6.03, so they "forked" it, to use the modern word. The question of support was always fraught. Compuserve offered all of their changes to DEC, who mostly sniffed at them. But from DEC's perspective, one of the major purposes of the VAX platform was to lock all that kind of thing down and go to a support model more like that of IBM.
Another part was pretty vicious infighting between PDP-10 (already sorta on thin ice from start due to fuckup that was PDP-6) and PDP-11/VAX teams, and VAX team won it pretty decisively - if in part through consolidation efforts.
EDIT: Another major difference was how PDP-10 was from an era where everyone with a (under)graduate students to throw at the problem was making custom modifications to hardware.
Like some early multiprocessor PDP-10 being done with hand-soldered MP bus done by students.
Popular claim by IBM PR, but the issue was that OS2fW component (which reused locally-installed Windows 3.x) had binary patches it applied to windows core component to turn it from DPMI host (which owns 32bit pagetable etc.) into DPMI client so that Windows would call to OS/2 for handling paging setup, and other details of interop.
The patches were made for Windows 3.1, but not for Windows 3.11 - since the changes resulted in binaries with different offsets, Windows 3.11 used under OS2fW would fail.
reply