4 Sep
2025
4 Sep
'25
10:35 a.m.
On 03/09/2025 21:48, Brian L. Stuart wrote:
Apologies in advance to anyone who gets this multiple
times.
I know a number of you are on more that one of these lists.
I'm looking for some information on a couple of the early
IBM unit record devices, in particular the Type 512A and
the Type 518. Ideally, I'd like to get the mechanical
dimensions in enough detail to create a CAD model.
As I assume you are aware, but perhaps others on here are not, that
these pre-date computing and must come from the era when data processing
involved only punched cards and I feel well before the term "Unit
Record" was coined. Sadly, this seems to be a forgotten era and there is
very little information about it on the web.
The background is that I'd like to improve the
model that
I'm using in my ENIAC simulator and I'm involved with a
school in Arizona that's working on a project to build a
full-scale model of the ENIAC. There's a letter from
IBM in the ENIAC archives that suggest the use of the
512A and the 518. So I'm pretty sure those are the ones
they used, but I haven't really been able to find any
details about them. We've found a fair amount of
information on the Type 513, and from photographs, the
punch used on the machine seems similar to the 513, but
is smaller.
Looking at the photographs linked from here:-
https://www.columbia.edu/cu/computinghistory/eniac.html
in particular
https://www.columbia.edu/cu/computinghistory/eniac6.jpg
I think you are correct, but I wonder if the 512A and 518 were
"specials" which is why there is little information on them.
I believe that in Punched Card processing normally you initially punched
cards by hand and any punches without keyboards were some kind of
calculating re-producer.
So for example on a loan system, you charged interest every 6 months.
For each loan you had a card with the loan amount.
You fed these into a calculating reproducing punch which calculated the
interest and punched a new card with the interest owing on it. (we
actually punched two)
You could use these to produce the interest letters. When the interest
was paid you could use the cards in a tabulator to print a summary of
the days/weeks payments.
After a month the cards you had left could be used to chase payment...
.. when I started work in 1976 one of my first jobs was to replace such
a system with screens....
So any punch you used probably had a reader attached and a plug board
that controlled how the cards were copied. The 513 is such a device. So
it has reader, plugboard and a punch.
I feel the devices ENIAC used were simply punches or readers. Looking
through the publicly accessible archives at
https://www.columbia.edu/cu/computinghistory/
its apparent that IBM had already produced custom versions of their
equipment, so it likely that these were specials.
The only other pictures I could find were in this book, 28th page in the PDF
http://www.bitsavers.org/pdf/ibm/punchedCard/Training/IBM_Accounting_Course…
which shows a reproducing punch so I wonder if that is a 512..
Thanks in advance,
BLS
I am sorry not to be more helpful
Dave