GARTHWILSON wrote:
it will be rather consistent
I've noticed that, too. The RAM contents on power-up will be fairly consistent, though not necessarily 100%.
I'm reminded of an experience from many years ago regarding a hardware/software package I was developing. Briefly stated, I had kind of outsmarted myself with some of the coding, and had unwittingly created a situation in which program behavior was reliant on a certain byte of RAM that never got initialized.
Due to the semi-consistency of the RAM's power-up data, I ended up with a bug that manifested itself only rarely -- a very nasty problem to deal with! Unfortunately the situation went from bad to worse.
As we know, intermittent symptoms usually indicate flaky connections or electrical noise. So I started making changes to the hardware -- I forget the exact details -- and, sure enough, I observed a difference in how often the bug would appear. Maybe I'd inadvertently changed the rate at which the +5 ramps up upon power-on -- could that affect the RAM's initial contents? I don't know, but one thing for sure is that I was wasting my time barking up the wrong tree. Although hardware
seemed to play a role, in fact the trouble was strictly a software issue.
The hours I spent unraveling the puzzle were not happy ones; I was pulling all-nighters trying to prepare a demo for the client. I don't recall ever having a bug that caused me more grief.
True stories from the trenches!
-- Jeff
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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
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