I am kinda stumbling forward on what I call my "Compact Stack" endeavor, meaning to have a small footprint pile of retro machines that covers most generations. Most of them are gonna end up being LPX or NLX type machines I think. Though there's a modern-ish ITX box and "biscuit tin" PC projects involved.

Compaq did some smaller form factors in their DeskPro line in the mid to late 90s, got a PIII in one of those, it's compact but deceptively heavy. NEC and AST had some small pre-pentium machines. When they made their own boards and didn't just build clones.

Around the turn of the century and a few years after there was the "book PC" form factor which seemed popular in Asia, but I have not come across any members of in North America.

konc wrote on 2019-09-25, 16:09:

cyclone3d wrote:

There are also some thin clients hat have a PCI slot available. Those are even smaller than the UNISYS systems.

This. If the target is Windows OS, check out those. Some have one PCI slot but you're not getting many more from a very compact PC either, so it is an option.

NeoWare CA2 has a combo ISA/PCI slot. Both TECHNICALLY can be populated, but the big thing is the ISA slot. Great for a DOS sound card.
It also has a VIA 800mhz CPU which can be slowed down quite a lot with setmul and cache disabling, and the included VGA chip is good for dos and VERY VERY early Windows 3D (like DX7)

There is the Multia by Digital Equipment Corporation (DEC). Came it two variants - a 100MHz Pentium or a 166-233MHz 64bit DEC Alpha 21066A. I don't have any experience with the Intel ones but the Alpha has integrated 2MB DEC 21030 (TGA) graphics, DEC 21040 Ethernet (Tulip). I think the Intel ones use S3 graphics instead of the TGA graphics chip. Both the Intel and Alpha versions were designed only to run Windows NT but I imagine DOS and Windows 3.x/9x would run on the Intel one too.

Expansion is via two PCMCIA slot and a single PCI slot. There is an NCR SCSI controller built into the PCI Riser board and the one PCI slot doubles as the machines only 3.5" drive bay. So you can have either a 3.5" SCSI hard disk or a PCI card. At the front of the machine there is a pair of 2.5" drive bays for a laptop IDE hard disk and floppy drive.

The Alpha variants case was re-used for two other products as well so not everything that looks like an Alpha Mutlia is one. The VT525 multi-session colour text terminal used the same case (not sure whats behind the sliding door), and I believe the VTLAN-40 terminal also used it with a ROM slot behind the sliding door. The VTLAN-40 was an x86 machine that ran Windows 3.1 and some terminal emulation software from ROM.

Depends on what era. I also have one of these UNISYS CWD 5001: UNISYS CWD5001
a bit limited on space but for a real older vintage Pentium it does work well for it's size...