[Coco] Linville's ramblings on assembly vs machine code

[Gene Heskett]

On Monday 10 July 2017 20:59:59 CoCo Demus wrote:

> Disassemblers cannot disasm jump tables like the ones used in OS-9
> co-modules. Also, to distinguish data embedded in the middle of the
> code machine code knowledge is useful.

Sleuth can, but you have to tell it whats executable, and what is data.

> On Mon, Jul 10, 2017 at 4:59 PM, James Jones <jejones3141 at gmail.com> 
wrote:
> > That's what disassemblers are for, save for programs that do tricks
> > like modifying themselves.
> >
> > Were I teaching assembly language, I'd show the instruction formats,
> > and then go into particular instructions as needed. Are you
> > wondering whether the order of registers in the push/pull
> > instructions makes a difference? Write assembly language that has
> > them in different orders, and see whether the generated bytes for
> > the two instructions as shown in the listing are the same. (If
> > memory serves, they are.) About span-dependent instructions, I'd
> > point out the different encodings and point interested students at
> > the relevant paper from CACM back in the 70s, (The general problem
> > is NP-complete, but there's an efficient algorithm that works for a
> > family of displacements that includes all but the most pathological
> > examples, and a good assembler ought to implement it.)
> >
> > James
> >
> > On Mon, Jul 10, 2017 at 12:38 PM, CoCo Demus
> > <retrocanada76 at gmail.com>
> >
> > wrote:
> > > Machine language is mandatory when you are debugging or
> > > disassembling
> >
> > code
> >
> >
> >
> > --
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> > Coco at maltedmedia.com
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Cheers, Gene Heskett
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