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List: tuhs
Subject: Re: [TUHS] Memory on Lion's v6
From: Andrew Hume <andrew () humeweb ! com>
Date: 2022-02-28 23:27:04
Message-ID: FDAF24B3-BB2A-4B23-8F01-55A7B2A8B183 () humeweb ! com
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the actual configuration of Lions' PDP 11/40 was
128 Kbytes of core memory,
a DJ11 terminal multiplexor and
three RK05 disc units each,
but note that because of the way the machines were bought,
and because of addressing weirdness (the top 8KB were memory-mapped to I/O \
registers), Lions' PDP actually had 112KB of main memory.
the PDP 11/40 had 18bits of address space, so while processes were limited
to 64KB, the system could have had 256KB.
> On Feb 28, 2022, at 7:48 AM, Clem Cole <clemc@ccc.com> wrote:
>
>
>
> On Mon, Feb 28, 2022 at 12:51 AM Will Senn <will.senn@gmail.com \
> <mailto:will.senn@gmail.com>> wrote: Does anybody know how much memory was \
> configured on the PDP-11 that Lion's used for the commentary system. Here's what \
> the book says about the system:
> ; from lions, page 1
> ; The code selection presumes a "model" system consisting of:
> ; PDP11/40 processor;
> ; RK05 disk drives;
> ; LP11 line printer;
> ; PC11 paper tape reader/punch;
> ; KL11 terminal interface.
>
> I usually add the mag tape, too
> ; TM10 magnetic tape - not in lions, but super handy
>
> It seems like he must have had an MMU and 128k memory, but I don't know. I'm hoping \
> y'all remember, know, or can otherwise divine the correct value. I've run with no \
> MMU - crash on boot. I've also run with less memory, but then cc won't build \
> mkconf, when I have the TM10 enabled kernel loaded. As a reminder, his book was \
> published in 1977.
> Thanks,
>
> Will
>
> Can't tell you definitively. You'd need to ask some one like Andrew.
>
> FWIW: the 11/40 has a MMU, but does not support split I/D like the 45. He has \
> 256K bytes [128k words] as the Max memory. IIRC v6 will boot with 48K words [96K \
> bytes] - maybe a little less. But the less physical memory, the slower the system \
> (the more it swaps).
> DEC was just switching to semiconductor memory at the time and it was pretty \
> expensive. The MS11-B was MOS based 18 bit x 4K word modules for the 11/45, which \
> were dual ported Unibus and Fastbus. I have forgotten what the 11/40 used as we \
> tended not to use DEC memory modules***.
> Lions and his team was likely to have been between 96K and 256K max, depending on \
> budget. In my experience, we tended to build up to max memory on systems, but \
> only as soon as we could afford it. In my experience, we often bought the machines \
> in phases... just enough to boot it, with two or three RK05's to start. Then add \
> more memory and more serial ports and more terminals. Then more (larger) disk and \
> maybe a tape drive and printer, and then even more serial ports and some sort of \
> modems and network connections.
>
> Clem
>
>
>
> *** At CMU during those days, we tended to use aftermarket memory or locally \
> designed memory boards on the 11/40 and 11/34s as EE/CS had negociate and bought a \
> few megabytes of memory chips from National Semi for C.mmp at a heavy discount - \
> other groups could add to that order as needed.
[Attachment #3 (unknown)]
<html><head><meta http-equiv="Content-Type" content="text/html; \
charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; \
line-break: after-white-space;" class="">the actual configuration of Lions' PDP 11/40 \
was<div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>128 \
Kbytes of core memory, <br class=""><span class="Apple-tab-span" \
style="white-space: pre;"> </span>a DJ11 terminal multiplexor and <br \
class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>three RK05 \
disc units each, <br class=""><div><br class=""></div><div>but note that because \
of the way the machines were bought,</div><div>and because of addressing weirdness \
(the top 8KB were memory-mapped to I/O registers),</div><div>Lions' PDP actually had \
112KB of main memory.</div><div>the PDP 11/40 had 18bits of address space, so while \
processes were limited</div><div>to 64KB, the system could have had \
256KB.</div><div><br class=""><blockquote type="cite" class=""><div class="">On Feb \
28, 2022, at 7:48 AM, Clem Cole <<a href="mailto:clemc@ccc.com" \
class="">clemc@ccc.com</a>> wrote:</div><br class="Apple-interchange-newline"><div \
class=""><div dir="ltr" class=""><div dir="ltr" class=""><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif"><br class=""></div></div><br \
class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Feb 28, \
2022 at 12:51 AM Will Senn <<a href="mailto:will.senn@gmail.com" \
class="">will.senn@gmail.com</a>> wrote:<br class=""></div><blockquote \
class="gmail_quote" style="margin:0px 0px 0px \
0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">
<div class="">
<font face="Helvetica, Arial, sans-serif" class="">Does anybody know how much
memory was configured on the PDP-11 that Lion's used for the
commentary system. Here's what the book says about the system:<br class="">
<br class="">
; from lions, page 1<br class="">
; The code selection presumes a "model" system consisting of:<br class="">
; PDP11/40 processor;<br class="">
; RK05 disk drives;<br class="">
; LP11 line printer;<br class="">
; PC11 paper tape reader/punch;<br class="">
; KL11 terminal interface.<br class="">
<br class="">
I usually add the mag tape, too<br class="">
; TM10 magnetic tape - not in lions, but super handy<br class="">
<br class="">
It seems like he must have had an MMU and 128k memory, but I don't
know. I'm hoping y'all remember, know, or can otherwise divine the
correct value. I've run with no MMU - crash on boot. I've also run
with less memory, but then cc won't build mkconf, when I have the
TM10 enabled kernel loaded. As a reminder, his book was published
in 1977.<br class="">
<br class="">
Thanks,<br class="">
<br class="">
Will<br class=""></font></div></blockquote><div class=""><br \
class=""></div><div class=""><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif">Can't tell you definitively. \
You'd need to ask some one like Andrew.</div><br class=""></div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif">FWIW: the 11/40 \
has a MMU, but does not support split I/D like the 45. He has 256K \
bytes [128k words] as the Max memory. IIRC v6 will boot with 48K \
words [96K bytes] - maybe a little less. But the less physical memory, the \
slower the system (the more it swaps). </div><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif"><br class=""></div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif">DEC was just \
switching to semiconductor memory at the time and it was pretty expensive. The \
MS11-B was MOS based 18 bit x 4K word modules for the 11/45, which were dual \
ported Unibus and Fastbus. I have forgotten what the 11/40 used as we tended \
not to use DEC memory modules***.</div><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif"><br class=""></div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif">Lions and his \
team was likely to have been between 96K and 256K max, depending on budget. \
In my experience, we tended to build up to max memory on systems, but only \
as soon as we could afford it. In my experience, we often bought the \
machines in phases... just enough to boot it, with two or three RK05's to \
start. Then add more memory and more serial ports and more terminals. \
Then more (larger) disk and maybe a tape drive and printer, and then even more serial \
ports and some sort of modems and network connections.</div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br \
class=""></div><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif"><br class=""></div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif">Clem</div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br \
class=""></div><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif"><br class=""></div><div \
class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br \
class=""></div><div class="gmail_default" \
style="font-family:arial,helvetica,sans-serif">*** At CMU during those days, we \
tended to use aftermarket memory or locally designed memory boards on the 11/40 and \
11/34s as EE/CS had negociate and bought a few megabytes of memory chips from \
National Semi for C.mmp at a heavy discount - other groups could add to that order as \
needed.</div></div></div> </div></blockquote></div><br class=""></div></body></html>
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