[TUHS] Early Unix Spider network

Noel Chiappa jnc at mercury.lcs.mit.edu
Sat May 27 23:52:59 AEST 2017

    > From: Paul Ruizendaal

    >>> The report I have is: "SPIDER-a data communication experiment"
    >>> ...
    >>> I think it can be public now, but doing some checks.

OK, that would be great to have online. I _think_ the hardcopy I have
(somewhere! :-) is that report, but my memory should not be trusted.

The people working on TCP/IP did know of the Spider work (like they knew of
the Cambridge ring work), but it didn't really have any impact; it was a
totally different direction than the one we were going in.

    >>> it turns out that the TIU driver was in Warren's repo all along:

V4?! Wow. I'd have never guessed it went that far back.

    >>> The code calls snstat()

    >> The object code for snstat() is in libc.a in the dmr's V5 image.
    >> Reconstructed, the source code is here:
    >> ...
    >> In short, snstat() is a modified stty call

Yes, I looked and found the original source, appended below.

    >>> Could that be the tiu sys call (#45) in the sysent.c table for V4-V6?

I wonder if we'll ever be able to find a copy of the kernel code for that
tiu() system call. And I wonder what it did?

    > [1] Oldest alarm() code I can find is in PWB1
    > ...
    > Either alarm existed in V5 and V6 .. or is was added after V6 was
    > released, perhaps soon after. In the latter case the 'nfs' code that we
    > have must be later than 1974

Remember, that source came from the MIT system, which is a modified PWB1.
So it's not surprising it's using PWB1 system calls.



/ C interface to spider status call

.globl  _snstat
.globl  cerror

        mov     r5,-(sp)
        mov     sp,r5
        mov     4(r5),r0
        mov     6(r5),0f
        mov     8(r5),0f+2
        sys     stty; 0f
        bec     1f
        jmp     cerror
        clr     r0
        mov     (sp)+,r5
        rts     pc

0:      .=.+6

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