Building a retro DOS PC. Part-1 Hardware



In this post I would like to describe my experience of building a retro DOS PC in 2023. I’ll explain my motivation for doing that and share some observations for those of you who might be interested in making such build yourself.

Here is my “new” minimally usable FreeDOS PC:

image My “new” retro PC

First, I would like to describe some reasons why anyone might want to build a DOS PC in 2023.

Motivation

  1. Nostalgia.

  2. Building a PC is a fun process in general and with enough efforts the result can be personalized to meet your aesthetic preferences. More options became unlocked after 30 years, such as using a newer and faster Solid State Drive in the same computer which uses older (but still faster) CRT monitor. Also there is an active community of enthusiasts who make new parts better than original (most notably sound cards) for the retro computers. As there is always something that can be improved in your current rig or the software environment - this hobby will keep you entertained for a long time.

  3. Getting a better quality / authenticity in old programs compared to the emulation. With all respect to the community of emulator developers, I see emulation as either a compromise to save the room space or a way to do unusual hacks (like connecting to a BBS via telnet using an old modem-oriented terminal in DOSBox). Running things on original silicon is just a more rewarding experience. (Especially with the video output on CRT - with crisp text in all resolutions, no screen tearing, smooth scrolling and authentic look).

  4. Having a zero-bloat, minimalistic computing environment. This is basically what people mean when they coin phrases like “when computers were fun to work with” or claim that “computers were faster when they were slower”. Old computers did much less unnecessary things, and they had much less abstraction layers sitting between the user and the application. Having less features, they often provided more stable and faster response time, faster start-up of the applications, or demonstrated performance comparable to the modern computers in interactive applications, using much less resources with the programs having much lesser footprint. Yes, with some efforts you can achieve a decent level of minimalism in Linux, for example, by working in Framebuffer, but the limited set of graphical programs written to support it makes it somewhat less practical than DOS. While Linux remains my main system, DOS was actually enough for personal computers. Generally speaking, writers, artists, musicians and architects did not need multitasking, systemd or display server. Sometimes they did not even need the CPU to run in protected mode. Neither do I need most of these things to enjoy computer art, listen to tracker music, tinker with the low-level programming, play my favourite games or read the old collection of the demoscene magazines.

Planning

First thing in building a retro PC is choosing the form factor, as it in turn affects everything else. My choice fell on Baby AT as this is what I had in my childhood (nostalgia). I thought that the earlier motherboards/cases could be too limiting, and I don’t need the advanced power features of a more modern ATX standard. I actually like to have a real hard power-off switch on the front panel, because I want to easily shut down the whole thing when I don’t use it (a soft power-off button would be one of those features which I don’t need, and which would be just wasting electricity. See minimalism).

Finding an original vintage PC case in 2023 can be one of the most challenging parts in the whole process, at least it was the case for me with the AT/Baby AT form factor.

After finding the case (with appropriate PSU) the next thing is choosing the motherboard. The rule here is simple - if you want to have audio in DOS programs, choose a motherboard that has 16bit ISA slots (and retro sound enthusiasts might need to have a couple of them). In fact, dropping support of ISA slots by the motherboard manufactures is the single reason why we stuck with the older hardware for running old programs natively, and it’s the reason why at some point in the past after another upgrade of your system, your favourite DOS games started sounding like crap. It looks like Socket 7 motherboards is a popular choice among retro gamers, so I trusted them and ordered one with K6-2 CPU, CPU-fan and RAM. If the motherboard is sold without Manual you can find it on the Internet, however if the Mobo comes without headers/brackets for the Serial/Parallel ports or the mouse - you might have a hard time finding them, especially for the mouse, because PS/2 pinouts on the motherboard side have never been standardized. (This article helped me to overcome this problem: https://www.razorback95.com/guides/ps2-mouse-header)

While my motherboard has the pins for USB connectors I don’t want to have any. I know exactly what peripherals I want to connect, so I don’t need the benefit of versatility provided by USB, nor do I want to have any drivers working in my system simply to support connecting a peripheral. Dedicated connectors operate with much simpler protocols and don’t require additional software.(Yes, minimalism again).

Making

Spending a day for cleaning and “retrobrighting” is necessary to get an acceptable look for these old cases. A picture with the case front panel before and after removing the yellowing:

image My “new” retro PC

Here is my complete list of items I used to assemble a minimal computer that can start in DOS:

With these components I assembled a PC that can launch and run FreeDOS, in the next posts I will tell about the Software side.

(c) 2024 Dmitry Usanov