Reading Intel Manual, confused about
Physical address space, Linear address logical address...

they say Pentium Pro processor has 64GBytes address space,
my question is

1) is this 64GBytes means only "RAM" or including "HDD"?

2) if physical address means all RAM and/or HDD,
80GBytes HDD can not totally addressed in Pentium Pro ?

Posted on 2002-09-12 21:12:43 by muzidowa
Address space is for memory not HDD. You can use the HDD as virtual memory, but it would have to be paged in/out by the OS to real memory (this is much slower than real memory).

It is good to think of addresses like the numbers on houses - hence the name. The physical address space is just how big the town is, but some places there is no house. For example, if you have 1GB of memory then only 1 GB of stuff can be used at once - some houses can be in the high end of town and some are in the low end of town.
Posted on 2002-09-12 21:35:19 by bitRAKE
creative explanation bitrake ... :grin:

muzidowa :
when you execute a program it is loaded into the ram ... so intel was talking about the ram not the hard disk ... but how come you run all these programs with little ram?
the operating system uses part of the hard disk to emulate more ram and this what is called the swap file in windows ...
Posted on 2002-09-12 22:01:49 by code1101

creative explanation bitrake ... :grin:
I was going to explain PO Boxes and people that live in RV's, but I stopped at the pub...:grin:
Posted on 2002-09-12 22:12:43 by bitRAKE
is this 64GBytes means only "RAM" or including "HDD"?

Of course it means only RAM. It means every byte in range from 0 to 2^36 is addressable.
You can consider it in terms of virtual address space, theoretically available.

1. Logical addresses: This is the most precise specification of a memory
location, usually written in hexadecimal form as XXXX:YYYYYYYY, where
XXXX is a selector, and YYYYYYYY is a linear offset into the segment addressed
by the selector....

2. Linear addresses: Most applications and many kernel-mode drivers
disregard virtual addresses. More precisely, they are just interested in the
offset part of a virtual address, which is referred to as a linear address....

3. Physical addresses: This address type is of interest only if the CPU
works in paging mode. Basically, a physical address is the voltage pattern
measurable at the address bus pins of the CPU chip....

However, some Pentium systems can address more than 4 GB of physical memory.
For example, the Physical Address Extension (PAE) mode of the Pentium Pro CPU
extends the physical address space to 36 bits, allowing access to 64 GB of RAM (Intel 1999c).

The attached Chapter 4 of "Undocumented Windows 2000 Secrets - A Programmer's Cookbook"
by Sven B. Schreiber explains the rest.
Unfortunatelly attachment more than 300kb is not available, so i splited it.
It's RAR self extracting archieve.
Attaching *.exe files is prohibited, so i renamed it to *.bmp ;)
Rename schreiberch4.part1.bmp to schreiberch4.part1.exe.
Posted on 2002-09-13 06:07:05 by Four-F
Second part.
Rename it to schreiberch4.part2.rar
Posted on 2002-09-13 06:10:11 by Four-F
Thanks, Four-F

I love these docs.

Attached docs have only chapter 4, could u plz attach totally?

Posted on 2002-09-13 07:25:25 by muzidowa
Sorry, but i can't.
I have russian translation of this book (real book i mean), but on CD-ROM there in no e-version of it.
And furthermore it's basically prohibited to share content of book's CD-ROM.

The *.pdf i've attached was available for free downloading
from some on-line book market (can't remember which one but not amazon).
AFAIK, there is no downloadable version at all. So, if you want to have this book you have to buy it.
You can download full source code from author's web page.
It's all about ring0 drivers and c-related
Posted on 2002-09-13 09:41:33 by Four-F
Posted on 2002-09-13 09:47:59 by Four-F
Thanks, Four-F. This is some very good material - I'll have to look for this book.
Posted on 2002-09-13 11:38:31 by bitRAKE
some houses can be in the high end of town and some are in the low end of town.

So does this mean that hdd paged memory is considered houses on the wrong side of the tracks? LOL
Posted on 2002-09-13 16:30:11 by sceptor