On 1 Mar 2008 at 21:44, Vincent Slyngstad wrote:
I think of blinkenlights as way ahead of a ROM with a
debugger in it,
and not for just the aesthetic reasons folks are talking about. It's
a little like Tony's fondness for "things he can understand".
Well, if I were debugging hardware, I'll take a logic analyzer and a
scope, thank you. I'm not sure how broad the range of hardware
faults is that a bunch of blinking LEDs will indicate. I'm not above
using a bus card with indicators and switches on it--but the card
goes as soon as the hardware gets debugged.
I earned my stripes in the big-iron days. Hands-on-dedicated time on
systems was hard to come by. Come in at 2AM or 3AM, in hopes of
getting some work done, hang around for the 9AM status report, go
home, eat supper and go to bed. A worse case happens when the
closest available machine is half across the country--and you have to
catch a flight to check out your system changes. It made me hate
travel something awful.
With hurdles like that, you tend to develop a habit of debugging your
code *away* from the machine. Even when time was available, often
there simply weren't any good tools. Try debugging a CDC 6600 PPU
program. No lights, displays or anything else to help you. If
you're patient and the CEs aren't too nosy (they don't like non-CE
types going behind the skins), you can grab a scope and read the P-
counter of a specific PPU--assuming that your code hasn't trashed its
memory and rendered any postmortem dump you get meaningless.
That isn't to say that I've never used a machine with an elaborate
front panel; I just never found one to be terribly useful in the long
run.
Cheers,
Chuck