Front panel switches - what did they do?
swiftgriggs at gmail.com
Tue May 24 11:32:19 CDT 2016
On Tue, 24 May 2016, Jon Elson wrote:
> The PDP-5 I did a fair bit of work on needed a bootstrap program loaded
> in from switches, it had no internal ROM for that.
How long did it usually take to do it?
> And, whenever a program crashed, it generally wiped the entire contents
> of memory, so the boot had to be reloaded by hand.
Uhh, ouch! That'll learn ya! You'd better be a careful coder, then I
> So, that was a big advance, a one-button boot.
Man, it seems so elementary now. Everything had to be invented sometime, I
> You could use the switches to patch a program you were debugging, look
> at memory locations to examine temporary data values, etc.
It seems like that'd make working with computers a lot more "intentional"
if you know what I mean.
> A few machines had lighted switches. These would generally be white
> buttons with lamps behind them.
Hmm, so not as cool as 60's and 70's TV and movies seemed to suggest.
Still at least it did happen. :-)
> The only one I know of that changed color was the power button ("key" in
> IBM-speak) on IBM 360's.
Heh, my grandmother was a Cobol programmer on IBM 360s for Western
National Gas (now Diamond Shamrock). She had mixed feelings about them,
but she said they had a decent development environment vis-a-vis some of
the competition at the time.
> IBM tape drives and disk drives had lighted buttons to show status,
> different color buttons and indicators gave them different colors, but
> they were generally just lit and unlit, but not multi-color.
Hmm, yeah, I seem to remember some similar style lights on old TEAC
reel-to-reel audio gear from that era, too.
> DEC PDP machines generally had a few switches that were multi-position,
> Such as stop/single-step and load address/examine, otherwise they were
> all on-off.
Those multi-position switches are really cool. They remind me more of
avionics style controls (which always seem to be the nicest physical gear
in terms of build quality).
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