jmtd → log → amiga → Amiga redux

Matthew blogged about his Amiga CDTV project, a truly unique Amiga hack which also manages to be a novel Doom project (no mean feat: it's a crowded space)

This re-awakened my dormant wish to muck around with my childhood Amiga some more. When I last wrote about it (four years ago ☹) I'd upgraded the disk drive emulator with an OLED display and rotary encoder. I'd forgotten to mention I'd also sourced a modern trapdoor RAM expansion which adds 2MiB of RAM. The Amiga can only see 1.5MiB¹ of it at the moment, I need perform a mainboard modification to access the final 512kiB², which means some soldering.

Amiga Test Kit showing 2MiB RAM

What I had planned to do back then: replace the switch in the left button of the original mouse, which was misbehaving; perform the aformentioned mainboard mod; upgrade the floppy emulator wiring to a ribbon cable with plug-and-socket, for easier removal; fit an RTC chip to the RAM expansion board to get clock support in the OS.

However much of that might be might be moot, because of two other mods I am considering,

PiStorm

I've re-considered the PiStorm accelerator mentioned in Matt's blog.

Four years ago, I'd passed over it, because it required you to run Linux on a Raspberry Pi, and then an m68k emulator as a user-space process under Linux. I didn't want to administer another Linux system, and I'm generally uncomfortable about using a regular Linux distribution on SD storage over the long term.

However in the intervening years Emu68, a bare-metal m68k emulator has risen to prominence. You boot the Pi straight into Emu68 without Linux in the middle. For some reason that's a lot more compelling to me.

The PiStorm enormously expands the RAM visible to the Amiga. There would be no point in doing the mainboard mod to add 512k (and I don't know how that would interact with the PiStorm). It also can provide virtual hard disk devices to the Amiga (backed by files on the SD card), meaning the floppy emulator would be superfluous.

Denise Mainboard

I've just learned about a truly incredible project: the Denise Mini-ITX Amiga mainboard. It fitss into a Mini-ITX case (I have a suitable one spare already). Some assembly required. You move the chips from the original Amiga over to the Denise mainboard. It's compatible with the PiStorm (or vice-versa). It supports PC-style PS/2 keyboards (I have a Model M in the loft, thanks again Simon) and has a bunch of other modern conveniences: onboard RTC; mini-ITX power (I'll need something like a picoPSU too)

It wouldn't support my trapdoor RAM card but it takes a 72-pin DIMM which can supply 2MiB of Chip RAM, and the PiStorm can do the rest (they're compatible³).

No stock at the moment but if I could get my hands on this, I could build something that could permanently live on my desk.