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).
More information about the cctech