For anyone who would like to break the 4GiB RAM limit in DOS.

For issues with communication ports, protocols, etc.
fatman2021
Posts: 90
Joined: Dec 14, 2013 0:43

For anyone who would like to break the 4GiB RAM limit in DOS.

Postby fatman2021 » Sep 17, 2017 20:19

Symmetric Multiprocessing (or SMP) is one method of having multiple processors in one computer system. In an SMP system (as opposed to a NUMA system) all logical cores are able to see the entire memory for the system. Note that SMP and NUMA are not mutually exclusive however; as Brendan has pointed out on the forums, Intel's Core i7 implements both SMP and NUMA, as well as hyper-threading.

http://wiki.osdev.org/Symmetric_Multiprocessing

What is long mode and why set it up? Since the introduction of the x86-64 processors (AMD64, Intel 64 (a.k.a. EM64T), VIA Nano) a new mode has been introduced as well, which is called long mode. Long mode basically consists out of two sub modes which are the actual 64-bit mode and compatibility mode (32-bit, usually referred to as IA32e in the AMD64 manuals). What we are interested in is simply the 64-bit mode as this mode provides a lot of new features such as: registers being extended to 64-bit (rax, rcx, rdx, rbx, rsp, rbp, rip, etc.) and the introduction of eight new general-purpose registers (r8 - r15), but also the introduction of eight new multimedia registers (xmm8 - xmm15). 64-bit mode is basically a new world as it is almost completely void of the segmentation that was used on the 8086-processors and the GDT, the IDT, paging, etc. are also kind of different compared to the old 32-bit mode (a.k.a. protected mode).

http://wiki.osdev.org/Setting_Up_Long_Mode
fatman2021
Posts: 90
Joined: Dec 14, 2013 0:43

Re: For anyone who would like to break the 4GiB RAM limit in DOS.

Postby fatman2021 » Sep 17, 2017 22:37

This article targets the user who wants to know how the CPU works. I will explain some assembly basics, the real mode, the protected mode, and the long mode. Working Assembly code is included, so you can test for yourself how the processor works in real mode, how protected mode is entered, how we get into 64-bit mode, and finally, how to exit from all of them and go back to DOS.

https://www.codeproject.com/Articles/45788/The-Real-Protected-Long-mode-assembly-tutorial-for
MrSwiss
Posts: 1922
Joined: Jun 02, 2013 9:27
Location: Switzerland

Re: For anyone who would like to break the 4GiB RAM limit in DOS.

Postby MrSwiss » Sep 25, 2017 21:03

Sorry, but I fail to see the relevance to FB, this is NOT a Assembly Programming Forum.
(there, that sort of stuff, would be relevant ...)

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