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43

8086 was designed to make asm source porting from 8080 easy (not the other direction). It is not binary compatible with 8080, and not source-compatible either. 8080 is not an x86 CPU. 8080 is a more distant ancestor that had some influence on the design of 8086, but it's not the same architecture. As an analogy, all x86 CPUs are the same genus but ...


42

The situation with the 386(DX) v. 386SX is similar to the situation with the 8086 v. 8088. The big issue isn’t the data lines (although they do have an impact on complexity and cost when routing a whole motherboard), the issue is mostly the cost of support components: motherboard chipsets (whether integrated or discrete), memory, etc. By going back to a 16-...


31

I very much doubt that anyone would ever have seriously considered fitting 4 GiB in a 386-based system, let alone designing such a beast. (To put this into context, I remember seeing early 1 GiB Alpha servers on the factory floor of Digital’s plant in Scotland in 1994, and those machines were priced at around $250,000...) The Red Hill hardware guide ...


22

To supplement @PeterCordes's excellent answer, I thought it would be worth going into the details of exactly how close to source code compatible the two processors are -- for example, how easy would it be to use textual substitutions (e.g. macros) to automatically translate 8080 code to 8086 code, and what the limitations would be. The first point would be ...


22

So that indicates extra data lines were very expensive; the difference between a 386SX and 386DX computer came to hundreds of dollars. Not really. Sure, they need to have some room and routing - and thus more thru hole connections, but over all, doing a 32 data lines instead of 16 isn't a big deal. It wasn't the data lines themselves, but rather the ...


19

We can see the datasheet of the 386DX here. The most important part is its pinout. We have address lines from A2 to A31. It means, that yes, it could have handled 4GB memory on a motherboard. Although it is very unlikely, that any ordinary PC motherboard had been built with the required number of memory sockets at the time. It is more likely, that it was ...


15

It's not just how many data lines, but where you have to route them. While the PPU on the NES does have its own independent RAM, it is connected only to the PPU. To update the tile RAM from the main CPU, all accesses must go through the PPU. This limits the extra 8 data lines and 11 address lines (for a 2 KB address space) to a small area of the board, as ...


15

The Intel 387 should work fine with an AMD 386DX; the latter was a direct clone of the Intel 386. The extra rows of pins are perfectly normal — see this photo for an example. (The extra pins were used for Weitek 3167 co-processors.) I'm not sure AMD ever produced their own 387; various on-line collections document the AMD 287, but not the 387. See here or ...


12

What you describe sounds like the PC Elevator: The PC Elevator 386 is a coprocessor-type accelerator board. The system's native CPU remains available for any programs that are sensitive to speed or timing. Software commands (Up for the faster 386 mode and Down for the slower speed) make speed selection simple. Initial startup via the Up command requires ...


10

I don’t recall SPARC systems having separate sockets for discrete FPUs; in particular, the Weitek SPARC POWER µP was a replacement SPARC CPU which derived much of its speed benefit from doubling its internal clock. On the x86 FPU side of things, quite a few different companies produced FPUs: Intel of course, AMD, IIT, Cyrix, Chips & Technologies... Many ...


8

iRMX III is a real-time operating system for Intel 80386 and later processors, originally developed by Intel and now maintained by tenAsys. A quick look at the System Call Reference manual reveals that it uses call gates.


8

The laptop you describe is unlikely to be able to support USB ports, for hardware reasons. But there may be an alternative solution. The first USB standard (version 1.0) was published in 1996, but didn't really gain traction in the PC market until version 1.1 was released in 1998. The PCI bus standard had been published in 1992, and by the mid 1990s it was ...


7

This is my best guess, but it looks really close. Could it be a Gigabyte GA-386PS? This block diagram looks very similar: I couldn't find the actual manual, but there are some jumper setting and connector details here


7

AMD 80386 chips are die-identical to Intel's, as AMD cloned the Intel 386. So, putting an Intel 80387 (or ULSI 80387 or IIT-387) will do fine, as long as their speed is equal or faster than the main CPU.. The row of socket pinholes is, efectively, for the less standard Weitek 3167 coprocessor, which was not binary compatible with the 387.


6

As someone who had a 386, I was happy just to upgrade from 4MB RAM to 8MB RAM. Just think of all the cool things I can do now?! At that point, my motherboard could not contain anymore RAM IC's, so the only way to upgrade further would have been to get denser chips. But by the time I needed more RAM I was on to a 486. Yes, you're correct about the theoretical ...


6

I confirmed this worked as expected, using Am386/DX-40 + Intel 387 co-processor. The trick with the Am386 is having separate clock for CPU/co-processor, as the former runs at 40 MHz and the latter at 33 MHz. The UMC-386 mainboard supports this configuration fine.


6

The tower is neither an invention of the 90s nor was it done by IBM. For example NCR sold their PC8 series in tower form factor since (at least) 1986 with 286 CPUs. IBM hat the PS/2 Model 60 in 1988 Many companies put x86 PCs into tower cases, already with 8088 CPUs Not to mention stands that where available to turn an IBM PC into a tower I bet with some ...


5

The tower form factor was well known in the 1980's, even IBM was using it at that time (the IBM RT 6150 was available in both desktop and tower cabinets, and IBM even had a tower stand option for the PC AT 5170). And it wasn't unusual to stand a desktop cabinet on its side; this practice was common in office environments when the system unit and monitor ...


5

MMURTL by Richard Burgess, was the subject of a book that Sams published as: Developing your own 32-bit Operating System. MMURTL makes no attempt at portability, instead making direct (and heavy) use of the 386's hardware support for tasks, task switching, and pretty much everything else. The licensing conditions for either/both the book and code are fairly ...


4

In such cases, the problem is almost always in one of three places: One of the memory modules. The motherboard itself. A plug-in device. To help with the testing, you should start be removing all non-essential devices form the system (CDROM, Network, HDD, other I/O). Just leave the keyboard, screen and floppy. Then re-run your tests. If it works, the ...


3

What kind of a PSU (in terms of wattage) do I need to comfortably run an AMD 386DX-40 system? Unlike with today's systems, the CPU played only a minor role in power consumption back then. Over all configuration, like number and size of disks as well as size of RAM was way more important. Hard to give any number without more information - like if it's just ...


3

Back in 1986, I was using an ICL Perq on a computing project when I was a student. As you can see from the photo, not only the computer, but also the monitor was in tower format. As you can also see, the tower itself was massive by today's standards. For reference, it was wide enough for an 8 inch floppy drive to be installed horizontally.


3

A completely different approach is to find an Ethernet card instead and use any available network resource (like a NAS or a Windows share on another host or the internet). I used 3com and xircom cards back then. You can use Win95 or a small 486 Linux distribution without too much elbow grease, and it will probably be the fastest in terms of moving data ...


3

Remove any cards, floppy drives, etc. that are unnecessary for showing the power-on screen or hearing the POST beep, then try to power on. If that still doesn't work, inspect the motherboard for bulging or leaking capacitors, leaky battery, or other obvious damage. Clean out any dust, as it may cause short circuiting. Reseat any socketed chips and any ...


2

PC specific, ignoring non-PC systems here. Remembering early-90s systems, 286 machines were mostly built in the "Baby-AT" form factor. Sometimes you still saw new 286/rarely 386 builds in the full-width AT form factor, which is surprisingly huge :). 386/486 machines were a common sight in both Baby-AT and minitower/full tower form factors. One likely ...


2

traal's answer provides some good ideas. I'd like to add a few. First, the PS/2 (at least the one I had back in the day, first half of the 1990s some time) will beep and do a RAM check on power up during POST, then proceed to try to boot the operating system. If I recall correctly, it will do so in that order, but it should definitely try to beep at you ...


2

You mention there are 4 2Mb modules. If I remember correctly, many 486 era boards would let you populate in banks of 2. If your board supports it, you can try removing 2 of the memory modules and running the system with only 2 installed. If the problem persists, it is likely to be one of the two remaining modules. If the problem goes away, then it is ...


1

I'd connect any PSU (with some more wattage) and then connect it to a Wattmeter ...so that one can measure the consumption when being idle and under full load. Likely it wouldn't even draw 100 Watt under load. ATX with adapter might be better than AT, because a) it being newer components and b) those can still be recycled into current machines - and it can ...


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