Australian ex-DEC ... Magnetic Delay line memory
rickb at bensene.com
Thu Dec 4 23:29:01 CST 2008
Jim S. wrote:
> If it was similar to the one in the Friden 130, then it would be able
> to store 4 registers of decimal numbers, since the 130 had a 4 stack
> register. It had 13 digits, don't recall and used a 5 bit (pulse)
> format for each number. That would suggest that there are 4 x 13 x 5
> or about 195 bits.
The delay line in the 130 and 132 store 480 'bits', but the
representation is somewhat unusual.
Each digit is allocated a slot of time on the delay line, and the digit
is represented by zero to nine pulses within the timeslot. The 'five
bit' representation is used in the four (or three on later versions of
the 130/132) counters that make up the arithmetic unit of these
machines. The delay line (as previously posted) is 50 ft. long (coiled
up), and has a delay of approximately 5 milliseconds.
Exhibit on the Friden 130:
In this exhibit there is a block diagram of the 130 that clearly shows
the unique architecture of the machine. It is really quite an elegant
design, the brainchild of Robert Ragen, Friden's chief electronic
The 130 actually has a total of six "registers" that are stored on the
stack. There are the four stack registers, one store/recall memory
register (not displayed), and another not-displayed temporary register.
> The site below has a good article on the Friden 132, but doesn't show
> the Friden's delay line, which is mounted flat on the bottom of the
> calculator below all the electronics.
I'll be posting a photo of the delay line in the Friden 130 exhibit
shortly. I just got my hands on a "display" delay line that has been
opened up. Just need to take a photo and post it.
> I don't know if the site's owner is on this list, but there is a lot
> good information on the Friden on the site w/o having to have one or
> tear yours up to look at the guts.
I'm on the list, and an avid reader, and sometimes poster.
The Old Calculator Museum
More information about the cctech