Sometimes I think that if it were the old days, I probably wouldn't have been able to program. I remember that these days we program on top of 64bit virtual addresses, but how did developers do it back then
16-bit x86 processors took 20-bit pointers, expressed as a 16-bit segment and a 16-bit offset. The segment was shifted four bits left and then the offset added. Which means there are lots of different segment:offset pointers that point to the same address. Segments are loaded into a segment register (one of CS, DS, ES, or SS) and then combined with an offset pointer in another register to create a pointer in this way. For example, 1e37:0008 would become 1e378.
It's complicated and janky as all get-out, but it made more sense if you were coming from 8080/Z80 development, as this was a scheme to ensure some degree of compatibility with 16-bit 8080 addressing while providing access to much more memory. 8086 was not binary compatible with 8080, but was designed so that 8080 programs could be machine converted to 8086 ones.
In languages like C, this took the form of three different types of pointers: NEAR, FAR, and HUGE. NEAR pointers were 16-bit offsets only, and dereferenced with respect to the current segment (usually in DS). FAR pointers were full segment:offset pairs but pointer arithmetic was only done on the offset which meant objects could be 64K max. HUGE pointers allowed for objects larger than 64k but at a significant performance cost.
I first found out about segmenting in 16 bit systems in 2016 by reading a lively explanation from an older edition of Duntemann's Assembly Language Step by Step (the newer editions focus largely on Linux and 32/64-bit systems).
You had to deal with two flavors of pointer, near and far. Far pointers came with segment selector, for accessing more than 64k. Your choice of memory model influenced the defaults. You might use near pointers for internal references in a module, and far pointers for external references.
I guess it was awkward to use languages that had higher level than assembly in order to write 16-bit programs that required more than 64KiB of memory. And also not quite portable, since they were all tied to x86 CPU. Those were messy times I guess. A somewhat similar story was 32-bit PAE, where the the CPU could address more than 4GiB physical memory, but software was still 32-bit and virtual addresses were capped to 4GiB. Linus was right that you must have more virtual memory (preferably 20+ times more) than physical, otherwise you have to jump through hoops.
I've been wondering about this lately. As a kid, I spent hour upon hour learning about computing: typing in Basic code from a magazine into a Commodore 64, playing with music on an Atari STe, learning my way around a DOS command line, dabbling with 3D modelling... just so much stuff that my own kids would never have the patience for.
I wonder if it's just that kids today (gods that makes me sound old!) are constantly surrounded by entertaining things to do - gaming, TV/films, music, social media.
I think that's actually a pretty accurate observation. I'm not a cognitive science expert, so I don't know the details, but there have been articles about 'popcorn brain' due to sustained attention issues, right? Personally, I use LLMs for coding quite often (in my environment, I'm often forced to use them). Compared to the past, when I use an LLM, the answers come immediately, so it seems harder to focus deeply than before. The generation younger than me, which is more focused on Shorts, probably has it even worse
I think it's an adaptation. Instead of living in a world with limited valuable information we're now living at the end of a firehose of never-ending near-useless information which has to be filtered at high speed.
Thats correct - and I notice that on myself. There are just much more things reachable at any point in time compared to our youth it takes real effort to focus.
I think they learned by reading books such as Undocumented Windows or Windows Internals (not to be confused with Windows NT internals), and Microsoft documents.
In fact, I’d argue it was more fun than programming Javascript these days.
It's complicated and janky as all get-out, but it made more sense if you were coming from 8080/Z80 development, as this was a scheme to ensure some degree of compatibility with 16-bit 8080 addressing while providing access to much more memory. 8086 was not binary compatible with 8080, but was designed so that 8080 programs could be machine converted to 8086 ones.
In languages like C, this took the form of three different types of pointers: NEAR, FAR, and HUGE. NEAR pointers were 16-bit offsets only, and dereferenced with respect to the current segment (usually in DS). FAR pointers were full segment:offset pairs but pointer arithmetic was only done on the offset which meant objects could be 64K max. HUGE pointers allowed for objects larger than 64k but at a significant performance cost.
Even with 32bit systems where you’d want more than 4GB RAM, application software still had 32 bit addresses (and thus 4GB memory limit).
I think it was a lot more common for 8bit systems to allow for 16 bit addressing though.
It’s been a while though. So hopefully I’m not misremembering things.
I wonder if it's just that kids today (gods that makes me sound old!) are constantly surrounded by entertaining things to do - gaming, TV/films, music, social media.
For me it is fascinating how today I can learn a foreign language, or how to code by interacting with the LLM.
In fact, I’d argue it was more fun than programming Javascript these days.