28 Jun
2007
28 Jun
'07
5:27 p.m.
------------------Original Message(s):
Date: Thu, 28 Jun 2007 15:52:56 -0700
From: "Chuck Guzis" <cclist at sydex.com>
Subject: Re: Billy Pettit real disappointment
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Message-ID: <4683D958.2968.16663E7 at cclist.sydex.com>
Content-Type: text/plain; charset=US-ASCII
On 28 Jun 2007 at 14:52, Jules Richardson wrote:
Yet another oddity discovered today: it would seem
that the rotating magnetic
fixed-head disk in the Burroughs L-2000/3000/4000/5000 machines wasn't for
secondary storage (as I'd assumed), it was the primary store in place of the
core typically found in systems of the time. I bet there can't be many
machines around which had rotating store as the primary memory.
Not at all uncommon during the 1950's. (e.g. LGP-30)
In fact, the Univac SS-80 that I mentioned not only has a drum as
main memory, but it's synchronized to the card reader. There were
two machines in the Univac "Solid State" series; the SS-80 for
conventional 80-column Hollerith cards and the SS-90 for Univac 90-
column cards. The layout on the drum was different for each.
The "solid state" refers not to transistors (which were used mostly
to drive indicator lamps), but rather to the magnetic cores used not
for memory, but for logical operations; one clock cycle per core.
The master clock was driven with 6 4X150 power tetrodes.
Very unusual--and very reliable for its day.
Cheers,
Chuck
-----------------Reply:
Nevertheless unusual for a machine in the L's size and price point;
these were essentially desk-sized accounting computers (posting
machines) used in banks and numerous small offices. The sealed
fixed-head disks were indeed very reliable; secondary storage
(when there was any, other than hard copy ledger cards) was on
PPT, EPC and on some models mag stripe cards and up to 4
digital cassette drives.
Later models (L6000 onwards) used 2102 RAMs ($800/2K).
BTW, the L's predecessor (E series) did use core memory and a
device called a core counter, a special core that emitted a pulse
for every 10th pulse in.
And to link this to another thread, I believe I still have a copy of
Lunar Lander for the L series; no display of any kind, just a
Selectric type golf ball printer. And speaking of golf balls, there
was also a golf game for them, as well as lots of ASCII art.
Here's hoping that one of the few people who have one of these
(other than Bletchley) will manage to get one going one of these
days...
mike