Windows XP x64 Edition was released for AMD64 around 2003-2004 before Intel’s x64 chips were out, the only CPUs were Athlon64.

I recall using XP x64 edition on an Athlon64. I remember it having such poor software support that it was barely usable. I heard it was actually a version of Windows Server that they put the XP GUI on top of, but I'm not sure if that's true (Wikipedia only seems to partially corroborate it).

>I heard it was actually a version of Windows Server that they put the XP GUI on top of

In a way, yes. It used the kernel from Server 2003.[1] Server/client kernels were unified for Vista SP1 and Server 2008, and not sooner just because the 2008 release lagged behind Vista's debut.

Prior to Vista, this kernel difference meant drivers for Windows server and client often had to be different builds. An anecdote that I recall was that although xp64 and 2003x64 could share drivers, it was typical to see drivers "not provided" for xp64, so the people who wanted that kernel just ran Windows Server as a desktop OS instead.

1: https://en.wikipedia.org/wiki/Windows_XP_Professional_x64_Ed...

I ran Windows XP x64 on my personal desktop until 2013. It was solid and dependable for me, though I did heavily customise it (custom Visual Styles themes, disabling features I didn’t like, some hacks to bring-forward sone features from Windows 7, etc)

Windows Server and Client were always much closer than appeared at first glance, as long as you lined up the versions. So it almost certainly was as described.

First 64 bit windows was running on DEC Alpha. Not Intel or AMD

Hi. Article author here.

It was but not when you think... 64-bit NT was never released. NT on Alpha was 32-bit.

It only leaked this month. I wrote about it:

https://www.theregister.com/2023/05/19/first_64bit_windows/

That’s true, but most Microsoft software was never ported to Alpha. Or Itanium.

So, you could get a 64-bit computer running Windows, but you wouldn’t be able to play Pinball, or read your emails, or run some other software you needed to work.

Oddly enough, the situation was much better with 64-bit Unix, where your usual tools worked flawlessly.

One of the unsung advantages of having the source available; you just need a compiler and some libraries and suddenly you have a ton of software even in an entirely new architecture.

Not all SW was easily to port from 32 to 64 bits. There are still open source programs which will not compile and run on 64 bits architectures.

This is one interesting reason why porting to different platforms (word size, pointer size, endianness) helps find bugs.

Also, that’s why we all should write unit tests.

By contrast, Apple in 2006 launched its first Intel Macs with 32-bit Core CPUs. Although new models with 64 bit-capable CPUs replaced them almost immediately (the June 2006 Macbook only lasted until November), that one decision caused a decade of software- and OS-related grief for Apple and its developers.

They were doing Windows NT for the Itanium. They were holding out hoping that this thing would take off.

I remember they didn’t port a lot of stuff to it - it was running mostly the BackOffice family of server apps.

I don’t think one could run Outlook on them.

When I was at Microsoft during the time I had X86, Alpha, MIPS, PPC (for a short time) and Itanium. We only did the builds for Itanium once in a while because the developers and the testers shared the expensive hardware. I believe the only versions of the product (Systems Management Server) were for the X86, Alpha and MIPS.