[TriLUG] Comparing a Univac 1105 with today's PC
hallman at email.unc.edu
Tue Feb 9 10:36:59 EST 2010
Thank you! Very helpful information. I wondered what all those cables on
the magnetic drum were for (see http://www.ibiblio.org/comphist/drum).
The ed-thelen.org site had info on weight and size (what an amazing
website!!!). Here's my revised blurb that I sent to the IT folks along
with your post:
The Univac 1105 at UNC-Chapel Hill had 8,192 36-bit "words," each of
which could be used to store an integer, floating point number, or 6
characters. In today's measure, its memory capacity was less than 50
It took .000008 seconds between initiation of a call for data from core
memory and delivery of the data (access time).
Auxiliary storage was a magnetic drum which stored 32,000 words with
access time of .017 second.
The computer weighed about 35 Tons. The floor space for the computer was
approximately 3,752 sq ft. The capacity of its air conditioning unit was
75 Tons. The computer was installed in the basement of a new addition
to Phillips Hall that was specifically constructed for this purpose,
with a recessed floor and plenum type of installation.
Peter Neilson wrote:
> Judy Hallman wrote:
>> The UNC Computation Center was dedicated in March 1960. We're working
>> on some materials celebrating 50 years of computing on campus. The
>> description of UNC's Univac contained:
>> Memory Capacity
>> Core (fast: access time .000008 second) 8,192 words
>> Drum (slow: access time .017 second) 32,000 words
>> With help from Google, I have:
>> The Univac 1105 at UNC-Chapel Hill had 8,192 36-bit "words," each of
>> which could be used to store an integer, floating point number, or 6
>> characters. In today's measure, its memory capacity was less than 50
>> It took .000008 seconds between initiation of a call for data from the
>> Univac's core memory and delivery of the data (access time). Access
>> speeds today are about 40 nanoseconds (.000000040 seconds).
>> Auxiliary storage was a magnetic drum which stored 32,000 words with
>> access time of .017 second. The average access time of today's typical
>> hard drive is roughly 5.6 milliseconds (.0056 seconds).
>> Does this look correct? Can you improve it?
>> Judy Hallman (UNC Class of '59)
> I would suggest giving timing specs in microseconds.
> There is a lot more information available online.
> See http://en.wikipedia.org/wiki/UNIVAC_1105 for a picture of the
> installation at the Bureau of the Census.
> http://ed-thelen.org/comp-hist/BRL61-u.html contains (rather far down on
> the page) a whopping amount of info including specifically the UNC
> installation. This was a vacuum-tube computer that used some
> transistors. The electrical power requirements were tremendous, 110 kw
> for the computer and 25 kw for the air conditioner.
> It is amusing to note that an additional 4k of core memory could be
> >>rented<< for $4500 a month!
> The magnetic drum almost certainly used head-per-track technology,
> rather than the moving head that's used on disks. Drums were expensive
> and tended to wear out in just a few years. A major use of drum memory
> was for "overlays" in which portions of the executable code would reside
> on drum and be called into core for execution as needed. This was prior
> to swapping and virtual memory, although around this time (1961)
> Burroughs already had virtual memory available in the B5000. The
> Burroughs sales staff saw no way to sell VM until after Univac and IBM
> had it five years later.
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