On Jul 2, 2016, at 1:37 PM, Fred Cisin <ci...@xenosoft.com> wrote:
> On Sat, 2 Jul 2016, Eric Christopherson wrote:
>> Genius.
> Clever? yes. Genius? no, or you would have to count too many of us.
>
>> But I would have thought CP/M would at least require a .com file to
>> have a header.
>> http://peetm.com/blog/?p=55
>
> NO.
> A .COM file is a pure image of memory, starting at location 100h.
> The "header" or "zero page" or "program segment prefix" is generated on the
> fly during the loading of the program.
> (There is a lot more to know about it)
Fred, I tried for years to understand the difference between .COM and .EXE. One
post of yours, and it’s clear. Thank you!
> The first thing that I did in CP/M was to create a zero length program. it
> seemed intuitively obvious as a needed capability.
> Didn't everybody realize that and do it?
> It never occurred to me to try to SELL it! In those days, there was almost
> an assumption that price would be proportional to program length.
I would urge caution in this regard. Depending on the distribution of the dots
on the price/length plot, it’s not inconceivable that a least-squares fit would
result in you having to PAY people to accept your program, depending on where
the line crosses the “price” axis ….
> For those who wanted "source code" for it:
> SAVE 0 A:JMP100.COM
> (SAVE was one of the five CP/M internal commands, ERA,REN,DIR,TYPE)
…. uh oh. Too late.
:-)
- Mark
