Re: Weird behavior of dd


The Natural Philosopher <a@xxx> writes many helpful answers to my naive
questions.

I was asked to replicate a C library on this particular board - it was
about as complex as a basic PC - so at other programmers would have
essentially stdlib there in the bios ready to call into. The actual
stdlib itself then became a dummy piece of code that translated calls to
the library into calls to the Bios.

There is some project to develop a Linux bios. Would you say that a lot
of what you had to do is now subsumed under that project?

The actual board was part of a large minicomputer. Its final function
was to be the first thing that booted..and it communicated by serial bus
with about 20 other actual boards and had to load them with THEIR
BIOSES, and get them to boottsrap, and if they failed, switch between
them..MIL spec minicomputers, with a LOT of diagnostics and internal
self monitoring.

One of the problems with just taking 20 PC motherboards and connecting them
is that the usual BIOSes need to detect the monitor or the video card, although
I've been told there is a way to defeat this. Maybe a custom BIOS is another
way.

A simulator is good, but it isn't an emulator. An emulators is a bloody
great box full of *** into which a computer plugs, and which replaces
the actual chip on the motherboard..so you can trace what is happening
to every pin on the chip, and halt it if soemthing intersting happens,
and see what caused it.

It sounds like a very expensive item, whether one buys it or builds it.
I gather that, in addition to having all the right signals, it has to have
them all at the right time. That probably implies that it has to be a lot
faster than whatever machine it is trying to emulate. The last time I
looked at stuff like this, which was decades ago, and superficially,
I heard about ECL (emitter coupled logic) as being the extremely fast
kind of chip but which required some special handling.

Cheap as chips haha. You can get a PIC board and software to put on it
for e $100 IIRC or even less. The PICS have mostly flash ROM that you
can program via USB. PLus loads of assemblers, simulatoirs and cross
compilers. All of which mostly run on Linux, those WINDOZE is better
served..

I have a real talent for getting hopelessly bogged down in irrelevant
details. It would probably be best if I tried to follow some book or other
document tailored to PIC and Linux. Can you recommend one? Of course,
most books and documents make some assumptions about what kind of
machines and equipment I have, which are never true in my case, which
is one of the reasons I tend to get hopeless bogged down in irrelevant
details, but not the only one.

Building your own computer though, is a several year task..

I found that out the hard way. It takes even longer when you don't have
the proper background and experience. And let's not even mention the
extremely high cost of ignorance.
--
Ignorantly,
Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx>
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.
.