[HECnet] A2RTR downtime

Tue Oct 19 16:31:25 PDT 2021

I can't remember now, but I believe the KA was de-supported from Tops-10 
in the 6.00 series monitor at some point.

What I recall was that WPI had a version of Tops-10 that was later than 
6.03B to where the KA support had been dropped.  They managed to put the 
KA back in and this is what we ran.  I /think/ this may have been 6.05.  
WPI also had an odd feature of a 'third' segment, but I couldn't imagine 
what that means nor how they did that; I was really starting to focus on 
Tops-20 at the time.

I don't remember when SMP showed up, but I'm pretty sure it would have 
been in some 600 series monitor.

I had been wondering what the user section count was for the SC30/40.  
The KL can do 5 bits (32 of them), which gets you 8 MW virtual, which is 
twice the maximum physical memory.  The TOAD can do 12 bits (4096), 
which gets you 1 GW.  I recall that the SC was "in between", but I can't 
remember that particular virtual limit.

I had thought that the TOAD (or some version) could do more than 32 KW 
physical.
> ------------------------------------------------------------------------
> On 10/19/21 7:07 PM, Peter Lothberg wrote:
>
> Fotnode, MRC gave me the BBN pager from Sails KA, and I later gave it 
> to LCM, together with  3 KA's and the BBN pager and the boards for the 
> KA to connect to the pager. In the late 80's we also did build a 
> ITS-pager for the KA.
>
> One of the KA's we brought up 6.03A on in 2019. Ralph Gorin pushed the 
> "read-in" button for that event.
>
> The SC30/SC40 can do "KI-Style" Tops10 10 pager and "KL-Style" Tops 20 
> paging. The Toad is 'special' it has a lot of the KC10 fetures and 
> don't do any "KI style" things and has 32MW of memory.
>
> -P
>
> ------------------------------------------------------------------------
>
>     *From: *"tommytimesharing" <tommytimesharing at gmail.com>
>     *To: *"hecnet" <hecnet at Update.UU.SE>
>     *Sent: *Tuesday, October 19, 2021 6:53:31 PM
>     *Subject: *Re: [HECnet] A2RTR downtime
>
>     I understand your point here and you are--of course--correct, yet
>     one hesitates to term Tops-20 (TWENEX ) paging as being a variant
>     of the BBN pager (or better TENEX).
>
>     The BBN pager was /far/ more capable then the both the KI and KL
>     pagers.  The KL pager was more capable than the KI, but this
>     didn't put it quite in the same league as the BBN pager in terms
>     of functionality.
>
>     This is most visible in what RPACS% (Read PAge ACess) returns (or
>     fails to return) and what SPACS% (Set PAge ACess) does (or fails
>     to do).  On the KL, the only access bit you can set is whether the
>     page is writable (this includes Copy-On-Write).  You cannot:
>
>      1. Clear all bits and thus set a page 'No Access'; it will still
>         be there
>      2. Set a page Write-only
>      3. Set a page Execute-Only
>
>     Case 1. is necessary for implementing guard pages which are (IMHO)
>     one of the very most effective hardware based debugging tools
>     around.  You really want "Explode on Reference" to catch stray
>     reads AND stores.  If you whack the page, then all that happens
>     the next time you touch it is it 're-materializes'.
>
>     Case 2 is great for increasing the security of certain
>     communications paradigms.
>
>     For 1., you can solve it in two convoluted ways. First, you can
>     hook the page creation interrupt and determine whether you are
>     creating something you ought not.  You can also actually implement
>     "Explode on Reference" by mapping 1+ the last page of a locked
>     file.  If you then try to touch that page, it will fail because
>     creating the page in memory involves creating it in the (locked)
>     backing store.  I discovered this by mistake when looking for a
>     guard page implementation for my FTP server.
>
>     2. Has no real solution, but paged mode IPCF% is probably good enough.
>
>     3. is partly solved by setting the file execute only, but this is
>     highly restricted and does not work if a program is multi-process
>     (I.E., forks).  Thus, I can not use it in the FTP server nor can
>     it be used in the Tops-20 TELNET client.
>
>     BBN repeatedly tried to get DEC to take their pager, but DEC never
>     went for it.  I don't remember what was designed for the Jupiter
>     or was implemented for the SC-40 or TOAD.
>
>         ------------------------------------------------------------------------
>
>         On 10/18/21 10:03 PM, Robert Armstrong wrote:
>
>             T10 in the last incarnation(s) could use the KL10 paging
>
>
>            Umm..  TOPS-10 could always use the "KL10 paging".  TOPS10 ran on the KL from day 1.
>
>            The thing is, the KL had different microcode for TOPS-10 paging and TOPS-20 paging.  The hardware didn't change.  TOPS-10 paging was the same as the KL10 paging, which was implemented in hardware.  TOPS-20 paging (or rather, TWENEX paging) was some variant of the BBN pager that was originally attached to a KA10 way back when.
>
>         Bob
>
>
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