Invisible <voi### [at] devnull> wrote:
> I had always assumed that the first computers were like current
> computers, just using relays or whatever instead of transisters, and
> with vastly inferior specifications.
>
> However, it appears that this isn't the case.
>
> For example, I thought they all used latch circuits for memory, but
> apparently not. There were things like core memory, which I'd never
> heard of. Presumably it's faster and cheaper to make core memory as
> opposed to wiring up thousands of latch circuits?
>

"Core" memory was invented in the late 40s, but didn't come into wide use until
the early 50s.  I think the IBM 360s used core memory. The IBM 370s and all
later machines used integrated circuits for memory.  We added 1MB of memory to
an IBM 370/168 in the mid 70s.  Price? $50000. There were several advantages to
core memory.  First its not volatile, you don't loose the contents of memory
when you power off the system.  Second its relatively immune to electromagnetic
radiation, so it does not require shielding when used in hostile environements.
Many military aircraft used core memory in their avionics.  I think the space
shuttles originally used core memory in their computers.

> Another example. According to legend, there was a time when if you
> wanted to run a program, you used a machine not unlike a typewriter to
> punch holes into a card. You "type in" the program onto punch cards like
> this, and only once the entire program and all its data has been punched
> do you even go near the actual *computer*. You feed the cards into a
> reader. It reads them all, and then spends the next six months running
> the program. Finally, you get a stack of new punched cards representing
> the results.
>
> Does anybody know approximately when this time was?

When I was at university in the mid to late 60s, I took a FORTRAN programming
course.  Punch program into cards, place in card tray, come back 4 to 6 hours
later and pick up your card deck and output listing.  Fix your typos and bugs
and repeat the above process until the program works.  At my first commercial
job, it was similar.  Punch you program into cards, place in the card reader,
and wait for the output to appear on the printer. Where I worked cards were used
until the mid 1980s.  We had cabinet after cabinet filled with punched card
programs.  The fun began after you punched in your 1000 card program and dropped
the deck on the way to the card reader.  After you did that a couple of times,
you started adding sequence numbers to the deck.

>
> For that matter, does anybody have a broad timeline of when various
> technologies were in use? What are the dates for things like core
> memory, drum memory, punch cards, magnetic tape, relays, vacuum tubes,
> transistors, ICs, etc?
>
> Was there ever a time when programs were entered into memory via
> switches rather than some other medium?
>
> Was there ever a "punched tape" medium similar to punch cards?
>
Yes. Several different varieties of tape. Different widths, different hole
styles etc.  I once had to write a driver for the IBM 1056 paper tape reader on
an IBM 370/158 because IBM did not support that device on that machine.  That
was kind of fun to do. That was in the early 70s?

> Similarly, you hear people talk about the VAX, the PDP, the varouis IBM
> mainframes and Cray supercomputers. Does anybody know the timeline for
> these, the technologies used and the basic design and performance details?
>
> (Sure, you can look up individual questions on Wikipedia, but the
> articles tend to contain huge amounts of minute detail about specific
> things. I'm trying to get a general overview of an entire era.)

I think you will have to look it up.  There is just too much information to
enter here.  I have work exclusively on IBM machines my entire career.  So I
can't say anything about other manufacturers. Very briefly IBM 360 series,
transistor circuits, core memory, mid 60s to early 70s. Early IBM 370 series in
the early 70s, integrated circuits, to later 370 series with higher density
circuits in the mid 80s.  The 3090 series machines with very high density
circuits until the mid 90s.  The s/390 series user cmos technology and were air
cooled.  The older machines used bipolar technology and many were water cooled.
Finally the z/series, again cmos technology.  Speeds ranged from .2 MIPS for a
360/50, 1 MIP for a 370/158, 15 MIPS for a 3083. The current machines I work
with today, 2 z/9 BC processors are rated at 600 and 335 MIPS.
The top of the line z/10 is almost 30000 MIPS.

Isaac

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