Comment by kibwen

PCIe is mostly backwards compatible with PCI, and bridge chips used to be quite common. ISA to PCI is harder, but not unheard of.

"SATA" stands for "serial ATA", and has the same basic command set as the PATA from 1984 - bridge chips were widely used. And it all uses SCSI, which is also what USB Mass Storage Devices use. Or if you're feeling fancy, there's a whole SCSI-to-NVMe translation standard as well.

HDMI is fully compatible with single-land DVI-D, you can find passive adapters for a few bucks.

There's one port you forgot to mention: ethernet! A brand-new 10Gbps NIC will happily talk with an ancient 10Mbps NIC.

It might look different, but the pc world is filled with ancient technology remnants, and you can build some absolutely cursed adapter stacks. If anything, the limiting factor is Windows driver support.

You're confusing quite a few things together.

The basic peripherals (keyboard and monitor) of today still present the same interface as they did back in the IBM PC era. Everything else is due to massive hardware expansion, not hardware churn.

How often do you update your drivers compare to your typical internet connected app? Software that handles the idiosyncrasies of the hardware (aka drivers) generally has a much longer lifespan than most other software; I don't see how you can reasonably say hardware breaking backwards compatibility is why software keeps changing.

Python programs do not care about SATA/PCI-E.

I don’t think I can take that claim by itself as necessarily implying the cause is hardware. Consumer OSes were on the verge of getting protected memory at that time, as an example of where things were, so if I imagine “take an old application and try to run it” then I am immediately imagining software problems, and software bit rot is a well-known thing. If the claim is “try to run Windows 95 on bare metal”, then…well actually I installed win98 on a new PC about 10 years ago and it worked. When I try to imagine hardware changes since then that a kernel would have to worry about, I’m mostly coming up with PCI Express and some brave OEMs finally removing BIOS compatibility and leaving only UEFI. I’m not counting lack of drivers for modern hardware as “hardware still changes” because that feels like a natural consequence of having multiple vendors in the market, but maybe I could be convinced that is a fundamental change in and of itself…however even then, that state of things was extremely normalized by the 2000s.

On the other hand, the main reason why Y2K happened was because a lot of major orgs would rather emulate software from the 60s forever than rewrite it. I'm talking like ancient IBM mainframe stuff, running on potentially multiple layers of emulation and virtualization.

We rewrite stuff for lots of reasons, but virtualization makes it easy enough to take our platforms with us even as hardware changes.

Pretty sure if I downloaded and compiled Tcl/Tk 7.6.x source code on a modern Linux box, it would run my Tcl/Tk 7.6.x "system monitor" code from 1995 or 1996 just fine.

Do you have any examples that aren't because of the OS (as in, not trying to run a 90's game on Windows 11) or specialized hardware (like an old Voodoo GPU or something)?

> x86 doesn't have magical backwards compatibility powers.

I never said it did; other ISAs have similar if not longer periods of backwards compatability (IBM's Z systems architecture is backwards compatible with the System/360 released in 1964).

> The amazing backwards compatibility of Windows is purely due to the sheer continuous effort of Microsoft.

I never mentioned Windows but it's ridiculous to imply its backwards compatability is all on Microsoft. Show me a single example of a backwards breaking change in x86 that Windows has to compensate for to maintain backwards compatability.

Eh. Emulators are often tiny in comparison to the programs they emulate. Especially when performance isn't so much of a concern - like when you're emulating software written for computers from many decades ago. A good emulator can also emulate a huge range of software. Just look at programs like dosbox and the like. Or Apple's great work with Rosetta and Rosetta2 - which are both complex, but much less complex than all the software they supported. Software like Chrome, Adobe Photoshop and the Microsoft office suite.

Arguably modern operating systems are all sort of virtual machine emulators too. They emulate a virtual computer which has special instructions to open files, allocate memory, talk to the keyboard, make TCP connections, create threads and so on. This computer doesn't actually exist - its just "emulated" by the many services provided by modern operating systems. Thats why any windows program can run on any other windows computer, despite the hardware being totally different.

Rich parents.