Yet another Hacker News

Why Windows 11 still ships with Windows 95's memory manager hidden inside it

65 points khalidkhair 1 day ago 37 comments

thighbaugh 1 day ago | parent

What else could be expected of Redmond's finest?

ForOldHack 1 hour ago | parent

A hidden z80 emulator...

Barrin92 51 minutes ago | parent

are you implying the fact that they proactively threw in a custom heap manager for a game is supposed to be a bad thing? The fact that almost any 25+ year old executable runs on Windows to this day is fantastic, they're seemingly the only guys who take backwards compatibility seriously.

ForOldHack 1 hour ago | parent

I wouldn't be surprised by windows components that use this. Wish I could run 16-bit apps tho.

ranger_danger 1 hour ago | parent

> Wish I could run 16-bit apps tho.

https://github.com/otya128/winevdm

https://github.com/leecher1337/ntvdmx64

hyperhello 1 hour ago | parent

I don’t know much about CPU and memory back then, but did they not have some kind of memory access debugging mode where it would match every access against the alloc map, understanding that it could be very slow, but would find some of this kind of bug? Come to think of it, do we even have that today?

jeffbee 1 hour ago | parent

This is what sanitizers do.

hyperhello 1 hour ago | parent

I know compilers have advanced, but I was wondering about a runtime debug check.

chuckadams 1 hour ago | parent

A sanitizer is that runtime debug check. The compiler just inserts those checks.

hyperhello 1 hour ago | parent

Okay. Then I have to assume that they didn't do it for SimCity! Thanks.

chuckadams 57 minutes ago | parent

Sanitizers come with a lot of overhead, and the tech wasn't readily available in SimCity's day, certainly not for Windows 95.

hyperhello 43 minutes ago | parent

I was imagining more like some kind of primitive CPU mode that sends every single RAM request to a software exception. Something you would normally have turned off but available for truly heavy duty debugging.

bboreham 18 minutes ago | parent

There was such a tool, called Purify.

https://web.stanford.edu/class/cs343/resources/purify.pdf

jeffbee 1 hour ago | parent

This is why memory allocators should be linked into applications and should not be considered operating system components.

rowls66 1 hour ago | parent

And when you are running more than one application at the same time how is that supposed to work?

hyperhello 1 hour ago | parent

It works fine. The processes get a fenced off piece of memory and are allowed to portion it out to themselves any way they prefer. Syscalls are designed to be mostly neutral about how the app wants to proceed.

bigfishrunning 1 hour ago | parent

On a system with an MMU, applications have their own address space that the allocator draws from; pages need to be centrally allocated, but individual allocations can be handled in userspace

pcwalton 1 hour ago | parent

Userland system DLLs need to allocate memory too.

irishcoffee 15 minutes ago | parent

Whenever I write I library I don't allocate memory. If memory needs to be allocated, the program calling into the library allocates memory and passes a pointer (or reference I suppose) into the library call.

Clearly this can't be enforced, but I've always found it bad practice to allocate memory inside a library.

abanana 1 hour ago | parent

> The tradition goes back to SimCity, which only ran on Windows 95 because Microsoft wrote special code for it... Yes, Microsoft modified its OS just to cover up one game’s bug... The SimCity hack was a one-off

The stuff around SimCity in this article is poorly written. It seems the author has misunderstood it to have been a one-off special case. I looked back at Joel Spolsky's article, and he does make it quite clear that the SimCity example was just one of many: "it still ran old 16 bit software perfectly. Microsoft obsessed about this, spending a big chunk of change testing every old program they could find with Windows 95".

The article does later mention "Windows XP’s hidden database of app fixes" but doesn't appreciate that the concept really started with Windows 95, and in a big way, not "just to cover up one game’s bug".

jonathanlydall 46 minutes ago | parent

The article’s content is generally quite weak, could probably have been covered in an old school tweet with screenshots and nothing of value would have been lost.

The only positive thing I can say about it is that it doesn’t appear to be written by AI.

I don’t think this person truly understands what they’re writing about, they did a little research, made some screenshots and put enough words in the article so that it will show up in search engines.

It’s reminiscent to me of many articles on Windows error codes, almost all of them are basically generic, generally quite long with drivel, and steering you to install some “fix it” software. Any technical person coming across these just finds them annoying as they clearly gamed the search results with unhelpful content.

pishpash 31 minutes ago | parent

One may even speculate the author got some, or a lot of ... "help", if it's even a real author.

jonathanlydall 22 minutes ago | parent

Nothing wrong with getting help from AI as long as you’re applying good and qualified judgment on what parts of its help is decent.

Chyzwar 14 minutes ago | parent

Your comment also do not bring anything interesting to discussion.

hoten 12 minutes ago | parent

good thing the comment wasn't swarmed in ads

Chyzwar 6 minutes ago | parent

I prefer ads over snarky dismissive hot air of someone ego.

tclancy 36 minutes ago | parent

Rough guess but this is all content farming of Raymond Chen posts at https://devblogs.microsoft.com/oldnewthing/ though I can't find a smoking gun. I definitely remember an article about Intuit doing something some dumb they had to keep an internal API around reporting the wrong value or something like that.

philipallstar 35 minutes ago | parent

From an article on this[0]:

> On beta versions of Windows 95, SimCity wasn’t working in testing. Microsoft tracked down the bug and added specific code to Windows 95 that looks for SimCity. If it finds SimCity running, it runs the memory allocator in a special mode that doesn’t free memory right away. That’s the kind of obsession with backward compatibility that made people willing to upgrade to Windows 95.

[0] https://www.joelonsoftware.com/2000/05/24/strategy-letter-ii...

Dwedit 52 minutes ago | parent

Why show a screenshot of a different game (SimCity 2000) when discussing SimCity?

jonathanlydall 43 minutes ago | parent

You can see my other comment, but short version is that I think it’s just content for the sake of content without the person actually really understanding the topic much more than most of their readers.

immibis2 6 minutes ago | parent

Because this article is an AI slop rehashing for SEO.

manoDev 31 minutes ago | parent

This is a great example of how implementation becomes the specification.

LASR 20 minutes ago | parent

Whatever one might think of Windows and Microsoft, the idea that you can still run apps that are 30+ years old is incredible.

expedition32 14 minutes ago | parent

Also Windows has a huge community of people who will help you.

With Linux you're stuck trying to decipher the ramblings of neckbeards.

officeplant 7 minutes ago | parent

it's not 1999 anymore, we've already moved past the golden era of stackoverflow and forums to support Linux & Windows questions into a new dawn of poorly sourced reddit bot comments.

Blikkentrekker 9 minutes ago | parent

This kind of neglect for backwards compatibility is honestly why quite a bit of free software is failing, and also why quite a bit is not that understands it.

Like the fiasco with Python3 and Wayland. It's so clear the developers just thought “Wow, people will just switch” not realizing how much people demand an absolute drop-in replacement and then maybe later you can think of slowly deprecating features to discourage new users from adopting them. Rust realizes this with editions. Yes, it's a big investment for them to continue to support it, but the alternative is that Python library maintainers now have to have this big investment themselves because they have to maintain like 6 different versions of the same library because Python doesn't understand the value of backwards compatibility. z/OS still supports 50s COBOL frameworks and for good reason. No one is going to rewrite that.

These developers when you talk about them really do not seem to understand that people aren't jumping to rewrite code or maintain different versions at the same time and very often even call them “lazy” for not doing it like they're not using their time for other things. Say you're a company, and you can pay a developer for his time:

1) Have him develop new features that make you more money.

2) Have him fix bugs that cost you money.

3) Have him rewrite existing code that will do nothing new, and will probably introduce new bugs again so you can later go to 2.

Which is more attractive?

150g2 8 minutes ago | parent

And yet scamming people with direct X.