Am 10.05.2018 um 04:31 schrieb Tony Thigpen:
Paul said:
> You're quibbling over semantics. A program that
> uses 32-bit data registers and 32-bit address
> registers and 32-bit code pointers and 32-bit
> data pointers is a 32-bit load module.
There is just so much wrong with that statement. Address registers are
only 31bit, not 32bit. The first bit is ignored on real IBM hardware.
Same for data registers, code pointers and data pointers. And there is
not such thing as a "32-bit load module" on *REAL* IBM hardware. (If
you want to talk 64-bit, that is another animal.)
No matter how many time you say it, it does not make it true. 32bit
does not exist on any IBM mainframe.
just for the record:
to support 32 bit virtual addresses, it is not really needed
that the underlying hardware supports 32 bit real addresses.
It would be possible to support 32 bit virtual on a 31 bit real machine,
if the DAT tables accept 32 bit virtual addresses as arguments
and yield 31 bit real addresses. So your argument, that the address lines
on the real IBM hardware only supports 31 bits is a weak one.
In theory, it would even be possible to support a 64 bit operating
system on a 31 bit hardware. That's one core feature of virtual memory:
supporting large address spaces on small machines.
That said, Paul's statements are anyway strange sometimes, because
he claims that his operation system (which he calles PDOS, IIRC)
will not make use of address translation ...
Kind regards
Bernd
You keep saying it is semantics. It's as much semantics as saying Red
is Blue.
Tony Thigpen
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
