CPU

I have a mad idea for a project that would run RISC OS and am considering laying out a board in KiCAD for a small production run. I’ve done boards based on an ARM M4 before but nothing as complex as this—but then what’s life without a challenge!

As far as the CPU goes is this the list of best supported models:

• Texas Instruments AM5728
• Texas Instruments OMAP5432
• Broadcom BCM2835/6/7
• NXP i.MX6 of some description

Broadcom BCM2835/6/7

That would be by far the easiest but getting a reliable source of the chips would probably be impossible. Broadcom don’t supply it to distribution, only directly and then the order has to have many noughts, I suspect 100,000 may not be entertained. Someone did pick up a few on the grey market to build prototypes of a Pi clone (IIRC on Kickstarter) but then were told they couldn’t buy them in quantity.

You’re a braver man that I am! Good luck! (I’ve laid out boards for multiple 6502s…but that was by hand, 2x scale on a light box, a LONG time ago…)

As far as the CPU goes is this the list of best supported models

Is that “models that have the best support” or “best models that we support”? :-) All the SoCs you’ve listed there are yet to receive an official, “stable” release of the OS (even-numbered OS version)

For SoCs/CPUs which have had stable releases of RISC OS 5 you need to look for (from newest CPU to oldest) OMAP4460, OMAP4430, DM3730, OMAP3530, IOP321, StrongARM, ARM7500FE, ARM7500, ARM710, ARM610.

We also have incomplete ports to the S3C2440 and S3C6410.

https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/HAL/S3C2440/
https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/HAL/S3C6410/

You’re a braver man that I am! Good luck!

Thanks! :—)

For SoCs/CPUs which have had stable releases of RISC OS 5

Very useful information – the OMAP4460 actually looks like it might be a good contender for what I had in mind (and its available in small batches). Thank you!