On Sun, 29 May 2022 17:11:33 -0700, Charles Mills wrote: >I have never programmed a Tab machine but here is what I know. > >The addition and so forth was purely mechanical. Anyone remember old-fashioned >mechanical adding machines? Picture a wheel with ten cogs on it numbered 0 >through 9. Let's say it is indicating 5. If you turn it three clicks it is now >indicating 8. Voila! 5 + 3 = 8. Let's say you turn it three additional clicks. >It is now reading 1, and on the way from 9 to 0 it poked the wheel to its left >one position. 8 + 3 = 11. > >Yes, the plug board's purpose was to hold the wires ... > Mid 1960s. A colleague told me (third hand story) of someone who had programmed a 407(?) to extract second differences -- differences of successive differences of successive inputs -- discrete second derivative.
The Numeric Analysis Center of the University of Colorado had an open-access SCM electronic calculator. Its registers were continuously visible on a CRT display in stroked characters. I could watch it extract a square root using Newton's Method in 44 seconds. Beside it was a mechanical Friden with cogwheel registers continuously visible. I could watch it extract a square root by subtracting successive odd numbers in 22 seconds. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
