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48

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 ...


24

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 ...


20

Yes. For example, the Xircom PE3-10BT is a parallel port adapter that allows an RJ45 connector be plugged into it. You don't get full 10 Mbps with it, but it works. Mine is powered via a PS/2 port passthrough plug and jack. I use mine with my 386 laptop.


19

I found this page on the motherboard, which says they are some sort of "32-bit external memory card." What are these slots? They are exactly that, memory expansion. This is a rather early 386 board from before memory modules became a thing. The mainboard can be fitted with 1 MiB using 256 KiBit chips (41256), so any expansion has to go on cards. With (AT)...


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 ...


14

The daughterboard is the graphics card. The GD610/GD620 is a quite common chipset for LCD/VGA graphics in laptops. It uses two 64k x 16Bit RAM chips to obtain 64k x 32Bit, which is the usual VGA memory (256 kBytes, but the VGA needs 32-Bit access to get the data fast enough to the screen). Those RAM chips have an access time of 100ns. The chips on your ...


13

If you have another computer to hook it up to and act as a bridge (or router), you could in principle run SLIP or PPP over the serial port to another machine. You're unlikely to get speeds exceeding 100 kb/s.


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 ...


11

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 ...


11

Since it's a pretty early laptop without a PCMCIA port, there won't be a way to add an Ethernet port. Your best approach is to use the serial port to connect via null-modem cable to a modern machine that either has an RS-232 serial port, or has hardware and drivers for bridging its USB port to RS-232 serial. Once the two are connected, use of the laptop as a ...


10

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.


10

Well, it could easy be a socket for a 387 type FPU. Size and number of pins would fit a 387 (or some pin compatible Cyrix FastMath) as PLCC carrier. On the other hand it's rather unusual to place it far from the main CPU, seen in the lower left. But without more information it's hard to say. Maybe some sharp close up can reveal markings supporting this?


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 ...


8

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.


7

One option is to use a modern Linux board to act as a fake modem connected to serial port. Then you can use any old software that would connect to internet by a modem connection, without actually having to pay the massive phone bills of the 1990s. The software setup is not very complex, mainly requiring installing ppp server on Linux. There is also a ...


6

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 ...


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 ...


6

To add to Raffzahn's answer: I strengthen the "might not be compatible to 16-bit cards" to "are most likely not compatible to 16-bit cards". As I see the traces on the photo, there is nothing that supports the impression these slots are ISA 16-bit compatible - but also no proof they are not. A reliable tool to learn more about that board is a continuity ...


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

It looks I got lucky, otherwise it would have been a long road. Apparently this laptop has a ROM-DOS on board in the socket. Due to bad contact it was not detected at startup. After I reinserted flash chip into the socket, it detected it and booted from ROM to DOS 3.3. It only had FDISK among useful tools there, but that was enough. It appeared, that BIOS ...


5

It's not a completely robust answer, but I found the following text archived at Computer Business Review from March 1987 that's primarily about Zenith's plans: In the UK, 27% of Compaq’s revenue comes from its 80386 The Compaq Deskpro had originally been announced only six months before that article, in September 1986. So based on the timeline: a 386 was ...


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 ...


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