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mschaef

1,993 karmajoined 16 лет назад

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mschaef
·4 дня назад·discuss
Many of those pictures look like great reasons for lockout tagout.
mschaef
·18 дней назад·discuss
> Even 256 meg of hard drive. That would have been impressively expensive in the 80s.

I only have a couple reference points around this scale:

My dad's company had a system set up with a searchable index of a bunch of legal testimony. It was a Compaq Deskpro 386 running Unix with an attached 1GB disk. The 1GB disk set up was as big as the machine itself.

A few years later, I worked with a Cyber mainframe equipped with around 30GB of total attached disk storage. The disk array literally filled a room.

256MB disk on an 80's PC would have definitely been quite a bit.
mschaef
·18 дней назад·discuss
> OK, but we spent a decade having to worry about this garbage, until the tooling finally caught up.

This was less about tooling than it was about economics - there was 32-bit hardware available in the personal computer space in 1984, if not before. The issue was cost. In today's currency, a 32-bit capable Mac was $8,000 with 128K. The first 32-bit capable PC was closer to $20,000.

That's a heavy lift in a world where a segmented architecture machine costs a fraction of that amount, runs software you might already have, and works the same way as your co-worker's machine.

> There were literally millions of man-hours wasted on segment registers.

A software developer in 1986 was not forced to deal with segment registers... but they often chose to deal with them to gain access a (much) bigger audience of potential customers for their software.

> A kludge that helped Intel conquer the world, but what a filthy, disgusting architecture, and what a waste of everybody's time and brain power.

The other side of the coin is that (for reasons I state above), segmented architectures got more capable software into more hands more quickly. It arguably did a lot for end users.
mschaef
·18 дней назад·discuss
> And this is the problem, it was very painful just to walk through a 200 KB buffer. This required compiler/runtime tricks, different selector increments in real vs protected mode, and special pointer types.

Most of that could be (and often was) hidden by the tooling. If you needed to bypass it, you could, but you didn't need to. That's not very different from today... there's a lot of hidden magic that can be bypassed if you need to for whatever reason.

I'd argue that these are useful engineering abstractions that made the best of a less than ideal situation. (The reality of the world being that there are no "ideal" situations... you have to work with what you have at the moment to solve the problem you have. These days, I'd argue that a pointer into a 'flat' memory space is counter productive to the extent it hides issues around cache hierarchy, NUMA, etc. In 1986, we had to worry that a flat memory space looked discontiguous. In 2026, we have to worry the a discontiguous memory space looks flat.
mschaef
·18 дней назад·discuss
That would make more sense. I was trying to imagine what sort of (custom?) hardware would accommodate that amount of memory back then. That was large storage even for mainframes the time. (The Cray 2 in the mid-1980's had 2GB, which was considered notably large.)
mschaef
·18 дней назад·discuss
I should preface this by saying I'm taking about x86 segmentation in general. On the 8086 you're right, but the 8086 can't address 2MB of memory to begin with. On the 80286 in protected mode, the situation is different in the way I'm about to describe.

The memory itself doesn't have to be contiguous.

2MB of 64K segments maps to 32 segments. So you need 32 locations in physical memory capable of storing 64K.

The programming model for addressing that block of memory necessarily includes both segment selectors and offsets. The segment selectors are indices into a segment table that contains the base address of each of the 32 segments. As long as the segment selectors themselves can be allocated contiguously in the segment table, you have enough to be able to compute which segment you need for which address in the 2MB range. It's the indirection through the segments table that maps it to physical addresses that do not need to be contiguous.

Raymond Chen talks a bit about how it worked in Windows 3.x here: https://devblogs.microsoft.com/oldnewthing/20171113-00/?p=97...
mschaef
·18 дней назад·discuss
There is no such thing as a "2MB program".... all you have is a program composed of <=64K segments, which are easy enough to fit into the hole.

If you do need something approaching a 2MB block of memory, you don't need a contiguous range of memory, what you need is a contiguous range of selectors, which is a different (and probably easier) problem to solve.
mschaef
·18 дней назад·discuss
> I had to use it to do image processing on a 256MB image buffer back in the 1980s in assembly language.... Give me a flat 32 bit memory address space any day (e.g. MC68000 around the same time.)

Huh?

There were no segmented x86 machines capable of addressing 256MB of RAM, aside from the 386 (maybe).

If you had a 386 and the $130K of memory your statement implies, you probably also could afford a Unix (or something else) license to get to that 32-bit address space. (If you weren't doing it all in memory, then you're having to depending on paging stuff out to disk, implying you either have a real OS or a flat memory model isn't enough to save you since you're manually having to page stuff to disk and back anyway.)

That's a super strange scenario you're describing.
mschaef
·18 дней назад·discuss
The 8086 was a stopgap measure to accommodate the fact the iAPX432 was in the middle of turning into the disaster it did. Given the engineering resources and timelines involved in the 8086, it wasn't a bad compromise approach.

> But more importantly it kept the x86 world for too long in that dead end that was 8086 mode programming > > "Oh if developers would just..." They won't. They haven't. And they will not ever.

8086 real mode programming in the mainstream lasted from 1981 until 1991 or so. The last 35 years have 32-bit (and later 64-bit) flat model addressing with pages for the most part. Seems like a reasonable transition period, really.

> In hindsight maybe a binary level translator from 8080 to 8086 would have worked better (and be simple enough)

Part of the reason they liked the segmented model is that it was possible to set the segments to the same value and then ignore them entirely. That gave a programming model for the 8086 that was sufficiently close to the 8080 that it was possible to use a sort of cross assembler to do something like what you suggest. You could then opt into 8086 specific instructions and segmentation as you needed. (Which took a few years... the first IBM PC's shipped with as little as 16K of RAM.)
mschaef
·в прошлом месяце·discuss
This is a small one, but significant to me.

I asked Claude to add support for multiple lights to my toy ray-tracer. It correctly added the support and then suggested adding colored lights to make it easier to diagnose. It felt more like a colleague making a useful suggestion than any sort of pure engineering tool.
mschaef
·3 месяца назад·discuss
From the sound of it, You may know this already, but there was a 1950's era plan to do something very similar to what you imply here:

https://en.wikipedia.org/wiki/North_American_Water_and_Power...
mschaef
·4 месяца назад·discuss
I think there are a couple questions you need to ask yourself - the first is why is it hard for you to be alone? You're the one person you're stuck living with for your entire life - it shouldn't be hard to be alone with yourself. That's where it began. That's where it will end.

You mentioned you have a therapist - this is something you might wish to explore with them.

The second question is related - what are you looking for in the "not alone"? What do you want? What would bring you peace? Are you looking for a relationship? A friend? Sex? etc? While you have to be comfortable with yourself, part of that comfort is knowing and being confident in what you're looking for. It may be that the world won't or can't provide it, but that's why I put this question second.

The final point I'll make is that there's nothing stopping you. You're an adult... within the constraints of the laws of your society, you CAN do what you want and there's nothing stopping you. It may not go the way you want, but it might, and wouldn't it be fun to try?
mschaef
·5 месяцев назад·discuss
Agreed, re: DeMuro.... I'm long past tired of hearing how "The ____ is the ____!"

I do like Tedward's videos, though. He seems a lot more honestly enthusiastic about it, and definitely has fun with the cars.
mschaef
·5 месяцев назад·discuss
That's a $125 salad spinner... I get the appeal, but it's definitely a premium product.
mschaef
·5 месяцев назад·discuss
I have half a dozen of them (including my father's from college) that I cherish, but do not use. I love the simplicity and elegance of the design. (Slide rules do a lot with operations that essentially boil down to addition, subtraction, and looking up function values in tables.)
mschaef
·6 месяцев назад·discuss
> The disinterest programmers have in using 80 bit arithmetic.

I don't know, other than to say there's often a tendency in this industry to overlook the better in the name of the standard. 80-bit probably didn't offer enough marginal value to enough people to be worth the investment and complexity. I also wonder how much of an impact there is to the fact that you can't align 80-bit quantities on 64-bit boundaries. Not to mention the fact that memory bandwidth costs are 25% higher when dealing with 64-bit quantities, and floating point work is very often bandwidth constrained. There's more precision in 80-bit, but it's not free, and as you point out, there are techniques for managing the lack of precision.

> A bit of background - I wrote my one numerical analysis programs when I worked at Boeing. The biggest issue I had was accumulation of rounding errors.

This sort of thing shows up in even the most prosaic places, of course:

https://blog.codinghorror.com/if-you-dont-change-the-ui-nobo...

In any event, while we're chatting, thank you for your longstanding work in the field.
mschaef
·6 месяцев назад·discuss
Does this have any similarities at all to the fact that the Pentium 4 used a 16-bit ALU?
mschaef
·6 месяцев назад·discuss
Thank you. As always.
mschaef
·6 месяцев назад·discuss
What do you mean by respect? Here's a layperson's perspective, at least.

Up through the 486 (with its built in x87), the x87 was always a niche product. You had to know about it, need it, buy it, and install it. This is over and on top of buying a PC in the first place. So definitionally, it was relegated it to the peripheries of the industry. Most people didn't even know x87 was a possibility. (I remember distinctly a PC World article having to explain why there was an empty socket next to the 8088 socket in the IBM PC.)

However, in the periphery where it mattered, it gained acceptance within a matter of a few years of being available. Lotus 1-2-3, AutoCAD, and many compilers (including yours, IIRC) had support for x87 early on. I would argue that this is one of the better examples of marginal hardware being appropriately supported.

The other argument I'd make is that (thanks to William Kahan), the 8087 was the first real attempt at IEEE-754 support in hardware. Given that IEEE-754 is still the standard, I'd suggest that x87's place in history is secure. While we may not be executing x87 opcodes, our floating point data is still in a format first used in the x87. (Not the 80-bit type, but do we really care? If the 80-bit type was truly important, I'd have thought that in the intervening 45 years, there'd be a material attempt to bring it back. Instead, what we have are a push towards narrower floating point types used in GPGPU, etc.... fp8 and f16, sure... fp80, not so much.)
mschaef
·7 месяцев назад·discuss
> I'm curious what the CX-83D87 and Weiteks look like.

The Weitek's were memory mapped. (At least those built for x86 machines.).

This essentially increased bandwidth by using the address bus as a source for floating point instructions. Was really a very cool idea, although I don't know what the performance realities were when using one.

http://www.bitsavers.org/components/weitek/dataSheets/WTL-31...