20 Oct
2021
20 Oct
'21
1:07 a.m.
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