Michael Wessel Gives the Vintage Scheider Euro PC a Boost with a Custom 8087 Coprocessor Add-On

Maker and vintage computing enthusiast Michael Wessel has built an upgrade board for the Schneider Euro PC personal computer, giving it something its manufacturer skipped: an 8087 math-coprocessor, alongside a more powerful NEC V20 CPU.

"All of this started when I discovered an old TurboC 3D graphics program of mine in my archives that I wrote in 1995," Wessel explains. "Imagine my disappointment when I found that my donut program runs at 0.05 FPS [Frames Per Second] on the 8088 Euro PC @ 9.54MHz! Even the wire-frame version runs at only 0.1 FPS. The ~5 FPS that I remembered from my 486-DX50 in 1995 had dropped to about 0.05 FPS (one frame every 20 seconds)! I did not expect this to be such a dramatic difference in compute. Wow!"

Released in 1988, the Schneider Euro PC was designed to compete with IBM's Personal Computer family. The machine was built around an Intel 8088 or compatible, typically from Siemens, running between 4.77MHz and a maximum 9.54MHz. With just 512kB of RAM, expandable to 768kB in the later Euro PC II, the specifications were sedate even at launch — but Wessel's particular example has enjoyed a range of aftermarket upgrades from a VGA-compatible graphics card to an Adlib-compatible soundcard — none of which made the 3D programs run any faster.

"Given the floating point intensive nature of the 3D graphics program, an obvious solution came to mind: an 8087 had to be added," Wessel explains, referring to a floating-point accelerator, typically dubbed a "math-coprocessor," released to provide the Intel 8088 with additional computational grunt. "Unfortunately, the Euro PC doesn't have a socket for one! Bummer!"

To fix that, Wessel designed a daughterboard that fits into the machine's existing CPU socket and which hosts both an 8088 CPU and a matched 8087 coprocessor — delivering a tenfold improvement in performance, boosted by a further 20 per cent by switching the original 8088 for an upgraded and fully-compatible NEC V20 processor. "In my final version," Wessel says, "I now use an NEC V20 and the 8087-2 at 9.54 MHz, and it runs stable without any issues in my Euro PC at about 1.2 FPS."

The project is documented in full on Hackaday.io, along with downloadable Gerber files to produce the adapter board — and Wessel's original 3D "donut" program, for those who'd like to try it out on their own MS-DOS compatible machines; the Gerbers are also available on GitHub under the reciprocal GNU General Public License.