70's computers

[Guy Sotomayor Jr]

> On Oct 24, 2018, at 11:22 AM, ben via cctalk <cctalk at classiccmp.org> wrote:
> 
> On 10/24/2018 11:57 AM, Al Kossow via cctalk wrote:
>> On 10/24/18 10:53 AM, ben via cctalk wrote:
>>> I have no idea what is in a modern home computer, but I suspect
>>> it still follows the same design of the IBM PC. Single CPU
>>> with segmented memory and bit of DMA here and there.
>> Wow...
>> You are out of touch, aren't you.
> 
> Am I really, every thing is so backwards compatable with the classic
> PC's I don't see much new other than what was hacked on.
> I am dealing with archiecture model here, the real hardware don't matter
> anyway. If it takes X cycles to read memory, it still X cycles where
> memory can be 10uS or 10pS. Ben.
> 
> 
Not so much anymore.  ;-)

None of the current OS’s have anything to do with the segmentation of x86
as it’s all gone as part of the 64-bit ISA.  It’s still there if you use the older
legacy modes but those are not used other than booting (and that will go
away soon too).

The lower level architecture is also significantly changed with out-of-order
execution, deep pipelines and large L1/L2/L3 caches.  Even though from
an ISA perspective, the x86 has only a few visible integer registers, with
OOO and register renaming (I think the current CPUs have 192 registers
that they can use for “renaming”) it isn’t much of an issue.

Oh, and I almost forgot.  You always have multiple CPUs (typically 2-8 on most
mobile and desktops…and that’s without hyper-threading enabled).
Servers are typically 16+ per socket and there can be upto 8 sockets
per server without getting esoteric (so for a typical 4 socket server you
can get 64-128 CPUs).

TTFN - Guy