baum@apple.UUCP (Allen J. Baum) (07/31/87)
-------- [] >In article <1893@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: > > While I have always had a keen interest in the history and development >of computers, and have collected and read many books on the topic, there is >one area which I have never seen mentioned: the early electronic calculator. >By "early", I am referring to 1966 and prior years. > My first electronic calculator experience was a Wang scientific >calculator in 1965. >Did they operate using some form of stored program control, and hence >a "software" algorithm for these exponential, log and trig functions? >Or did they have dedicated hardware logic for each mathematical function? These are my interests as well. As I recall, the Wang's did have some kind of programmed or microcoded control. I don't recall which algorithm was used (Taylor-series, continued fraction, etc.), but I believe it was different from what HP used on their HP9100. The HP9100 was an amazing machine, and resulted in my first programming experience. Internally, it was a highly microcoded bit serial, decimal machine. It did not have an adder! All it could do is increment or decrement a decimal digit! It counted one down, and another up until the first equalled 0, and then went on to the next digit to perform an addition (similarly for subtraction). Multiplication, and all the CORDIC routines it used for the log, exp, and [hyper][arc]trig functions. The HP65 handheld programmable almost exactly duplicated its functions years later. The microprogram control was an inductively coupled 14-layer PC board! The Russians actually copied this, ROM & all. It must have been fun to peel apart those 14 layers..... -- {decwrl,hplabs,ihnp4}!nsc!apple!baum (408)973-3385
cy@ashtate (Cy Shuster) (08/05/87)
That Wang calculator, with nixie tube display ("readout"!), was the first
machine I ever programmed, too. It used PortaPunch cards, and had a card
reader kind of like a vertical waffle iron: a latch let a hinged side flop
open, you insert card, and close it back up.
Aside from fond nostalgia, what was amazing to me about the machine was the
nature of the programming language. The machine itself was just a large,
floating point calculator, with four memory locations. The punch cards
simply had a code to represent each key on the keyboard! The display was,
of course, the accumulator -- and hitting the +M1 key was merely a Store
instruction. Constants were entered by, obviously, just hitting the number
keys.
There must have been a few extensions to allow real programs: a jump
instruction, for example. And I think there was even a way to allow input
of variables from the keyboard. But I still think that the calculator
analogy -- where an op code is just a keyboard function key -- is very
apt when trying to teach people assembler language.
I still miss the 1401, though, with variable word lengths and decimal
arithmetic! *Surely* there must be an Autocoder emulator for the PC out
there somewhere? If I get a card reader, I can put my PC on it!!
--Cy-- ...!seismo!scgvaxd!ashtate!cy (UUCP)