Those are SRAMs. A 286 system wants DRAM, which is usually a lot cheaper.

https://www.geeksforgeeks.org/difference-between-sram-and-dr...

286 doesnt want anything, CPU is ram agnostic. Project author didnt want to mess with implementing DRAM controller, not that its difficult. Here a simple 16 bit controller realized with ten 74xx chips https://amigaprj.blogspot.com/2013/05/amiga-fast-ram-expande...

Oh right, I didn’t read far enough to see there’s no DRAM support - very unusual for a 286 system (at least a PC-compatible one). That’s a big tradeoff, indeed. Thanks!

I wouldnt call it a tradeoff. Author didnt want to design memory controller, and SRAM gets him effortless 0 wait state access.

Personally Im also a fan of keeping ram oldschool. I even reverse engineered a ram card for a 386 board just last week https://github.com/raszpl/386RC-16

The tradeoff would be speed and implementation simplicity against the high cost of SRAM, like you highlighted :)

(Re your 386 RAM board: Nice necroproject!)

Ah, OK, it is all static RAM? Ouch...

> about $500-1000 https://eu.mouser.com/c/semiconductors/memory-ics/sram/?memo...

Only because you're including RAM spec'ed at 75pS access times.

If you limit the selection to 133MHz (the slowest 'max speed' - ridiculous, you can still easily purchase NEW 50nS and 70nS SRAM elsewhere, this is why I don't buy from mouser)...

Then the price falls to £5 for a 32MB (256Mbit) chip, which isn't excessively priced, but it still more than I paid for similar chips a few weeks ago.

Thats a serial Pseudo SRAM you are looking at :)