From: John Cowan <cowan@ccil.org>
To: Ron Natalie <ron@ronnatalie.com>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] A language question
Date: Wed, 1 Sep 2021 14:43:06 -0400 [thread overview]
Message-ID: <CAD2gp_TM9kZuUhmMB=-ySJGk8cHz=i7pefPcJAUAEbqh--drHA@mail.gmail.com> (raw)
In-Reply-To: <emb7ef3194-1912-4969-9763-7a703eefabc9@alien>
[-- Attachment #1: Type: text/plain, Size: 1258 bytes --]
On Wed, Sep 1, 2021 at 12:07 PM Ron Natalie <ron@ronnatalie.com> wrote:
> I disagree. TRAP according to the processor handbook was intended to be
> used for what UNIX calls system calls. EMT was the emulator trap used to
> simulate other operating systems on the same hardware.
>
The 1969 PDP-11 Handbook <
http://gordonbell.azurewebsites.net/digital/pdp%2011%20handbook%201969.pdf>
says on p. 41 (PDF page 49): "[Trap] instructions provide for calls to
emulators, I/O monitors, debugging packages, and user-defined
interpreters", but it does not define "emulators". (The OED has several
citations for this sense of "emulator", but before about 1985 the context
seems to be hardware emulation only.)
Nevertheless, DOS/BATCH-11 (1970-71) already uses EMT as the system call
instruction, and it is clear that TRAP was for user use. At that point,
the only other operating system that could be emulated would be the Paper
Tape Software that I mentioned, which used IOT.
(BTW, RSTS/E's hypervisor would reflect any EMT instruction to the RTS (the
actual or emulated supervisor running in any given process, such as
Basic-Plus, RT-11, RSX-11, or Teco), with the exception of an EMT 377, EMT
377 sequence, which was a syscall to the hypervisor itself.)
[-- Attachment #2: Type: text/html, Size: 2344 bytes --]
prev parent reply other threads:[~2021-09-01 18:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-01 13:23 Richard Salz
2021-09-01 13:28 ` Dan Cross
2021-09-01 13:44 ` Clem Cole
2021-09-01 14:23 ` Paul Winalski
2021-09-01 14:29 ` John Cowan
2021-09-01 15:59 ` Ron Natalie
2021-09-01 18:09 ` Warner Losh
2021-09-01 18:43 ` John Cowan [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAD2gp_TM9kZuUhmMB=-ySJGk8cHz=i7pefPcJAUAEbqh--drHA@mail.gmail.com' \
--to=cowan@ccil.org \
--cc=ron@ronnatalie.com \
--cc=tuhs@minnie.tuhs.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).