Re: [OSDev] How to switch to long mode in x86 CPUs?

On 02/03/2025 08:22, Paul Edwards wrote:

"Scott Lurndal" <scott@slp53.sl.home> wrote in message
news:JdFwP.46247$SZca.36276@fx13.iad...

"Paul Edwards" <mutazilah@gmail.com> writes:

"David Brown" <david.brown@hesbynett.no> wrote in message
news:vprtt6$3jah9$1@dont-email.me...

On 27/02/2025 16:57, Ar Rakin wrote:

>

>

Do you consider the concept of a BIOS (as seen as the IBM PC),
"legitimate to use"

>
In the abstract, possibly.  But the last half century has
shown that BIOS as an I/O abstraction layer was a bad idea
from the start.
>

and do you consider MSDOS (which uses that
BIOS) to be an operating system?

>
No, MSDOS was, is, will always be a simple program loader.

 Plus manages memory.

How does it do that? I seem to recall that you got 640KB minus whatever the resident parts of the OS needed.

Plus manages file systems
Plus provides an API
Plus provides a device driver interface
Plus provides a command shell
Plus provides other utilities

My memories of it was that it provided a file system used via some API, and some keyboard and text screen i/o (I can't remember if it handled a mouse).
It didn't provide drivers for graphics hardware, or low level libraries for it, or GUI libraries, or printer or plotter drivers (whatever was necessary for vector and raster outputs), or floating point libraries ...
Which was fine by me. I just needed it to load and run my program, which usually switched the machine to some graphics mode, and when it terminated it went back to the DOS command prompt in text mode, and the user could then run some other program.
I wish Windows was still that simple.