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DubaiXTClone — 8088 Turbo 8MHz PC/XT Motherboard with Static RAM

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First post, by mr.spencer

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Hello everyone,

This is my first post.

I wanted to share a PC/XT motherboard I designed, based on the IBM 5160 and influenced by the many Taiwanese turbo clones of the era. I called it the DubaiXTClone.

The main differences from a standard XT design: 8MHz turbo with runtime speed switching, static RAM (no refresh), reduced IC count, 4-layer PCB, and real-time bus activity LEDs driven by otherwise unused gate outputs.

Fully open hardware under CERN-OHL-W v2 — schematics, PCB and PAL source code all included.

Tested with JUKO 2.31, Turbo BIOS 3.1 and others. SVGA Trident, 3COM, RTC, Floppy, and XTIDE all confirmed working in turbo mode.

As a side note, it also runs LMChat (https://github.com/spencer-uk/LMChat), a chat client that connects the board to a local LLM via LMStudio.ai application - ELKS and MS-DOS, both are supported.

GitHub: https://github.com/spencer-uk/DubaiXTClone/

(in the picture: top board DubaiXTClone, bottom IBM5160 - for comparison)

Happy to answer any questions.

~Spencer

Reply 1 of 6, by rasz_pl

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nice one, should probably also post it here List of open-source PC hardware projects

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/Zenith_ZBIOS Zenith Z-386 MFM-300 ZBIOS disassembly

Reply 2 of 6, by mr.spencer

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Will do that. Thanks for the feedback rasz_pl, appreciated.

Reply 3 of 6, by CharlieFoxtrot

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This is very cool! I built a Micro8088 with backplane and couple of Kiselev ISA cards couple of years ago and it was extremely fun project. I will definitely check out this in detail and maybe build this one too.

Reply 4 of 6, by BitWrangler

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Intriguing, I'll put it on my list of possibles for the "someday I'll scratch build" list... in the vein of a Jedi builds his own lightsaber.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 5 of 6, by Babasha

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Is your board compatible with 1MB of RAM?
If so - how you made high 384KB adressing/shadowing of other technology of access?

Need help? Begin with photo and model of your hardware 😉

Reply 6 of 6, by sjeffers

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Spencer

Thanks for all the work you put into this project. I'm getting all the parts and material together to build one.
I have a question about the 4 220pf capacitors; on the schematic they are shown on the IOW, IOR, MEMW and MEMR lines, in the picture of the bottom of the board they appear connected to the XIOW, XIOR, XMEMW and XMEMR lines. Which is correct? I'm assumimg the schematic is correct but want to make sure.

Scott

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