Path: utzoo!attcan!uunet!yale!lisper-bjorn
From: lisper-bjorn@CS.YALE.EDU (Bjorn Lisper)
Newsgroups: comp.arch
Subject: HP2100 (was: Re: Self Modifying Code)
Message-ID: <33895@yale-celray.yale.UUCP>
Date: 20 Jul 88 02:24:24 GMT
References: <5254@june.cs.washington.edu> <76700032@p.cs.uiuc.edu> <361@scolex> <835@l.cc.purdue.edu> <7362@ico.ISC.COM> <2317@pt.cs.cmu.edu>
Sender: root@yale.UUCP
Reply-To: lisper-bjorn@CS.YALE.EDU (Bjorn Lisper)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 43

In article <2317@pt.cs.cmu.edu> lindsay@k.gp.cs.cmu.edu (Donald Lindsay)
writes:
>
>The idea of storing a return address into the front word of a subroutine
>was widespread. It would be nice to think that this rank stupidity died out
>long ago, but in fact the HP 2100 series worked that way. (I believe it
>went off the market in the 1980's.)

I had the "pleasure" to maintain such a system during my previous existence
as an engineer, in the early eghties. Our system had a whopping 96K 16-bit
words primary memory and two disk drives of 5Mwords and 20Mwords,
respectively. It was purchased sometimes in the late seventies for a sum I
would guess was well above $20,000. (The system was used!) The software for
this machine was, well, medieval. Some of the (mis)features of its operating
system, RT-IVB, were:

* It did have time-sharing, but the memory was statically partitioned and
  the only way to change the partitioning was to generate a new copy of the
  operating system!

* Max address space for a program 64K. No virtual memory, so if you needed
  more then explicit segmentation with code overloading was the only way to
  go.

* Dumb terminal drivers that didn't recognize ^S & ^Q, not to mention the
  nifty block transfer protocols their own 264x series terminals were
  capable of (which, amongst other things, made these terminals' function
  keys useless).

* A contiguous-storage oriented file system that frequently lead to
  disk space fragmentation problems. Whenever that happened you had to
  switch to single-user mode and run a disk compaction program...

* Much, much more, but I have occupied enough bandwidth with this already. I
do have to mention, though, the listings of reported bugs that came every
three months or so. A not too unusual comment after a bug report was: "this
bug will not be fixed"! I guess HP didn't put in too much manpower into
supporting this system. I also guess that they were right in not doing so...

When I write this, using GNU emacs under Xwindows on a $4000 sun 3/50, I
realize that things have gone the right way since my engineering days.

Bjorn Lisper