640k Was Never Enough For Anyone: How DOS Broke Free

On modern desktop and laptop computers, there is rarely a need to think about memory. We all have many gigabytes of the stuff, and it’s just there. Our operating system does the heavy lifting of working out what goes where and what needs to be paged to disk, and we just get on with reading Hackaday, that noblest of computing pursuits. This was not always the case though, and for early PCs in particular the limitations of the 8086 processor gave the need for some significant gymnastics in search of an extra few kilobytes. [Julio Merion] has an interesting run-down of the DOS memory map, and how memory expansion happened on computers physically unable to see much of it.

The 8086 has a 20-bit address bus, giving it access to a maximum of 1 megabyte. When IBM made the PC they needed space for the BIOS, the display, and the various accessory ROMs intended to come with expansion cards. Thus they allocated a maximum 640k of the map for RAM, and many early machines shipped with much less than that. The quote from Bill Gates about 640k being enough for anyone is probably apocryphal, but it was pretty clear as the 1980s wore on that more would be needed. The post goes into how memory expansion worked, with a 64k page mapped to switchable RAM on a card, and touches on how DOS managed extended memory above 1 Mb on the later processors that supported it. We dimly remember there also being a device driver that would map the unused graphics memory as EMS when the graphics card was running in text mode, but such horrors are best left behind.

Of course, some of the tricks to boost RAM were nothing but snake oil.

8086 header: Thomas Nguyen, CC BY-SA 4.0

A Web Server, The Sixteen Bit Way

If you were to talk about sixteen bit computing in retrocomputing circles, misty-eyed reminiscences of the ST or Amiga would emerge. Both fine platforms, but oddly the elephant in the 16-bit room has become a victim of its own success. DOS, the granddaddy of all PC operating systems, seems oddly overshadowed by its 68000-based competitors in a way it certainly wasn’t back in the day. Perhaps it’s the often-atrocious graphics when cards designed for business graphics were pressed into gaming service, but it’s easy to forget that DOS PCs were the powerhouses of their day. They still pack a punch even in 2023, as [Lunduke] is here to show us by running a DOS web server. Take that, nginx! Continue reading “A Web Server, The Sixteen Bit Way”

Myth Tested: DOS Can’t Multitask

It’s a piece of common knowledge, that MS-DOS wasn’t capable of multitasking. For that, the Microsoft-based PC user would have to wait for the 80386, and usable versions of Windows. But like so many such pieces of received Opinion, this one is full of holes. As [Lunduke] investigates, there were several ways to multitask DOS, and they didn’t all depend on third-party software.

A quick look at DESQview and Concurrent DOS was expected from this article, but of more surprise is that IBM had a multitasking DOS called TopView, or even that Microsoft themselves released the fully multitasking MS-DOS 4.0. We remember DOS 4 as being less than sparkling, but reading the article it’s obvious that we’re thinking of the single-tasking version 4.01.

From 2023 it seems obvious that multitasking is a fundamental requirement of PC use, but surprisingly back in the 1980s a PC was much more a single-application device. On one hand it’s surprising given the number of multitasking DOS products on the market that none of them became mainstream, but perhaps the best evidence of the PC market simply not being ready for it comes in the fact that they didn’t.

If you fancy experimenting with DOS multitasking, at least machines on which to do it can still be found.

MS-DOS Meets The Fediverse

By now, most Windows users are set up with decently functional machines running Windows 10 or 11. Of course there are a few legacy machines still lagging behind on Windows 7 or 8 and plenty of computers in industrial settings running ancient proprietary software on Windows XP. But only the most hardcore of IBM PC users are still running DOS, and if you have eschewed things like Unix for this command-line operating system this long you might want to try using it to get online in the Fediverse with Mastodon.

The first step is getting DOS 6.22, the most recent version released in 1994, set up with all the drivers and software needed to access the Internet. At the time of its release there were many networking options so the operating system didn’t include these tools by default. [Stephen] first sets up an emulated NE2000-compatible networking card and then installs the entire TCP/IP stack and then gets his virtual machine set up with an IP address.

With a working Internet connection set up, the next step on the path of exploring federated social media is to install DOStodon (although we might have favored the name “MastoDOS”) which is a Mastodon client specifically built for MS-DOS by [SuperIlu]. There are pre-compiled packages available on its GitHub page for easy installation in DOS but the source code is available there as well. And, if this is your first time hearing about the Fediverse, it is mostly an alternative to centralized social media like Facebook and Reddit but the decentralization isn’t without its downsides.

That Handheld 386SX Gets A Teardown

A few weeks ago our community was abuzz with the news of a couple of new portable computers available through AliExpress. Their special feature was that they are brand new 2023-produced retrocomputers, one with an 8088, and the other with a 386SX. Curious to know more? [Yeo Kheng Meng] has one of the 386 machines, and he’s taken it apart for our viewing pleasure.

What he found is a well-designed machine that does exactly what it claims, and which runs Windows 95 from a CF card. It’s slow because it’s an embedded version of the 386 variant with a 16-bit bus originally brought to market as a chip that could work with 16-bit 286-era chipsets. But the designer has done a good job of melding old and new parts to extract the most from this vintage chip, and has included some decidedly modern features unheard of in the 386 era such as a CH375B USB mass storage interface.

If we had this device we’d ditch ’95 and run DOS for speed with Windows 3.1 where needed. Back in the day with eight megabytes of RAM it would have been considered a powerhouse before users had even considered its form factor, so there’s an interesting exercise for someone to get a vintage Linux build running on it.

One way to look at it is as a novelty machine with a rather high price tag, but he makes the point that considering the hardware design work that’s gone into it, the 200+ dollar price isn’t so bad. With luck we’ll get to experience one hands-on in due course, and can make up our own minds. Our original coverage is here.

New DOS PCs, In 2023?

It’s not likely that we’ll talk about a new PC here at Hackaday because where’s the news in yet another commodity computer? But today along comes not one but two new PCs courtesy of the ever bounteous hall of wonders at AliExpress, that are unusual enough to take a look at. If you have around $250 to spare, you can have a brand new, made in 2023, 80386sx plamtop PC capable of running Windows 95, or an 8088 laptop for DOS. Just what on earth is going on?

Continue reading “New DOS PCs, In 2023?”

PC Classics, Right In Your Browser With EmuOS

[Emupedia]’s work to preserve computer history by way of making classic and abandoned games and software as accessible as possible is being done in a handy way: right in your browser with EmuOS.

A few moments of BIOS startup kicks off EmuOS right in a browser window.

Doing things this way has powerful “Just Works” energy. Visit that link in a modern browser and in no time at all you’ll be looking at a Windows 95 (or Windows 98, or Windows ME) desktop, filled with a ton of shortcuts to pre-installed and ready-to-run classic software. Heck, you can even keep it simple and be playing the original Microsoft Solitaire in no time flat. There is also a whole ton of DOS software waiting to be fired up, just double-click the DOSBox icon, and browse a huge list. The project is still in development, so not everything works, but the stuff that does is awfully slick.

Here’s some additional background that goes into more detail about the project and its capabilities, but if you’d prefer to just click around to explore, here’s the main link again (and here’s a list of mirrors.)

If OS emulation is your thing, don’t miss emulating the IBM PC on an ESP32 microcontroller. And if you’re more into lesser-known vintage operating systems, how about re-inventing PalmOS to run on x86 architecture?