What: Small custom form factor PCB to make a x86 compatible PC, with integrated sound chip for adlib and SB Pro audio. Let's face it, this is for vintage DOS and Windows gaming mostly, no one in their right mind would use this for work. I made 2 units successfully!

Pros: extremely satisfying small form factor, fanless, noiseless, runs on 5V, supports a joystick, cpu frequency BIOS divider all the way down from 800 MHz to 25 MHz and L1/L2 cache enable/disable. USB support. Ethernet.

Cons: VGA output only makes it difficult for people without a monitor or screen with this input (VGA to HDMI is a whole new level of wild beast to tame), gotta make do with no CD drive (use SHSUCD for dos or clonesheep in Windows to mount .iso as virtual drives), not a walk in the park to set up the microSD for your OS, no line in nor microphone in for audio. Probably way too expensive for many people (probably 2x or 3x the cost of an equivalent true vintage, although not compact, working system), though your milleage may vary and depends on how willing you are to hunt for parts, pay for shipping and duties. 

Who: This project originally by theRasteri (forked from a few revisions from his last one).

Watch this to understand what it's all about: https://www.youtube.com/watch?v=aJEp4ZUG7BI

I've successfully ordered the front and back plate PCBs as well as the main board PCB from PCBWay, ordered the components from Mouser.ca and various parts elsewhere (see below for a list) and successfully assembled it and proved for myself that the revision I forked from works as is. I've been using both of the machines I assembled for a few months now with little issues (the issues I encounter are mostly due to the finicky nature and configuration of the vintage DOS and Windows programs I try to use, as is the norm back in those days!).

DISCLAIMER: I'm a beginner hobbyist electronics enthusiast. Use these files at your own risk. Double check my output. I'm not the best at using altium circuitmaker and may have accidently messed things since I made the output files that were used to print the boards that work for me. If you want to stay closer to the original design, go fork theRasteri's original project. The difference I'm aware of:

In theRasteri 's latest revision, some 0603 packages were replaced with larger 1206 packages + some traces are slightly moved but are logically identical in purpose. We both had trouble using the EEPROM for reprogramming in DOS with software, so I ended up with a different EEPROM chip as well as pull-up resistor (3.3K) for it, and I can confirm it works perfectly with what is listed. Both forks lead to working machines.

A possible improvement is to use a higher amp rated polyfuse. If you draw current from the USB port, it may pass above its 1A limit since the SOM itself can consume 0.9A under heavy load as per its datasheet. For the time being, I simply replaced my polyfuse with a solder bridge with no issues for months - otherwise sudden reboots would happen.

PCB Ordering: the only thing worth mentioning is that the front and back plates should be at 1mm thickness instead of the often default 1.6 mm. If you take the latter, you'll stumble upon the problem of not being able to insert/eject your microSD card easily and forcing the issue might break the connector itself (it's not super sturdy to begin with).

IMPORTANT: DO NOT TRUST octopart with the crystal when it says 16.000 MHz. While you may get adlilb and sound blaster playback going, it WILL NOT play coherent MIDI music. You will also have trouble reprogramming the EEPROM. Get the legacy 16.9344 MHz crystal, it's what's used to reach the digital sampling playback of that day with integer division. (The schematic and board diagrams list the right frequency - only the octoparts component list is wrong and there's no way to correct it).

PARTS NOT IN MY ATTACHED MOUSER.CA BOM:

1) Remember to get board mating connectors (4 sets) for your SoM, I got mine from ICOP directly by communicating that need (it doesn't show up on their website):
4x ICOP SOM304 SX/RD/MX+/DX2/DX3 Dev Board Mating Connector"  PH2*38(1.27)-5.3MM

2) Sound chip (U3) was bought from UTsource, check the external link

3) System on module  (U1) was bought from ICOP (see external link; you can also try DM&P Electronics Group)

4) Optional S2 Dreamblaster daughter board was bought from Serdashop (see external link)

5) HAMMOND 1457J1201 extruded aluminium case (can also come in black)

OSes successfully used: MS-DOS 6.22, Windows 98 SE
Games successfully played: King's Quest VI, Descent (with Dos32a extender), Full Throttle, Starcraft and Brood Wars, SkyRoad, Duke3d, DOOM

External gear successfully used: USB 1.44 mb disk drive, Roland MT-32 through the gameport midi out pin, Roland SC-88ST (same pin), USB mouse (in DOS, it's bad in Win98se), USB Keyboard (good in both), PS/2 keyboards, PS/2 optical mouse (both DOS and win98se), PS/2 IBM mouse (both DOS and win98se), various Gravis joysticks and gamepads, ethernet connection to a modern router.