My current QL accelerator project

[Will James]

Woo-Hoo!!!! I had to do a little update. The photo is of the first time the QL PiStorm has booted up to QDOS.
After sorting the hardware a few days ago I've been scratching my head since then as to why it was locking up instead of booting
today at work I had a revelation - A18 and A19 are not decoded on a standard QL causing the RAM test to go into an eternal loop of doom.
Also, I stupidly failed to remember that the QL doesn't have just a 128k address space, it is 256k, 128k of ROM and IO with 128K of RAM on top of that.
I made a couple of simple changes, hit return and guess what popped up...

Think things are going to progress a little faster now, I have already worked out how I am going to ensure the microdrives will
run correctly using the Pi counter as a register in the QL to ensure accurate timing what ever speed PiStorm is used.
This will mean my Oqtadrive should work too.
I am also going to emulate a WD1702 floppy disk interfaced to a USB FDD plugged into the Pi so I can still read all my old floppy disks.
Finally, I am planning 2 HDMI screen modes on the Pi, one that will be a direct copy of the QL screen but in HDMI instead of RGB. The other
will be a full 24bit HD 1920 x 1080 screen that the QL screen will be mapped onto but will also be able to be accessed in HD separately.

Once this is done I will be making an Amiga 4000 version using a Raspberry Pi 5 compute module, probably after I get back from
holidays over the summer. Shouldn't take so long this time.

Oh happy day!

[Pr0f]

That is impressive!

[Will James]

Pah! it's not reading the keyboard... something to do with my interrupt handling I'll wager.

[Peter]

For me, it remains somewhat unclear what makes the Musashi emulator under Linux preferrable to sQLux.
But as a technical achievement, this is impressive work. Thanks for the update!
Fortunately QL interrupts are autovector. I'm curious if SuperBASIC will run after the implementation.

[Will James]

Hi Peter, for me what makes the QL PiStorm a better option is that it is going to give my actual QL hardware, that has a lot of sentimental value, a new lease of life... I will still be able to use microdrives and floppy disks. Just by plugging in a little card it will update the spec. It is also just the start, because now I've got it figured out it will be a doddle to keep it up to date in future with ever faster Raspberry Pi5s. For example, I will be rewriting the ps_protocol.c protocol file to work with Raspberry Pi 5 for my future Amiga 4000 PiStorm. Once this is done I can easily update the QL version to make it even faster... I just don't get the same happy buzz using emulators on a soulless pc. For example, I am writing this on a pc using my Sinclair ZX Spectrum+ which I have turned into a HID PC cherry keyboard... it just makes me smile. (It also works in ZX Spectrum Emulator mode if I want to run Spectaculator).

[Peter]

Hi Will, I hope I didn't come across negative - I have a lot of respect for your technical achievement.
I know that software emulator can do a lot more than the original QL - and that is of course still true if it is mounted inside the QL.

Hi Peter, for me what makes the QL PiStorm a better option is that it is going to give my actual QL hardware, that has a lot of sentimental value, a new lease of life...

Stiil, if I want a software emulator inside the QL, it's easier to mount a Raspi with a matrix keyboard adaptor and run sQLux.

I will still be able to use microdrives and floppy disks.

Okay, the microdrives are point I understand. For me they always were good riddance and unused for over 30 years, so I didn't consider.
Floppy are just USB drives on the Raspi, so that's no advantage over other software emulators.

It is also just the start, because now I've got it figured out it will be a doddle to keep it up to date in future with ever faster Raspberry Pi5s.

I had read about difficulties with the Raspi 5 in the Amiga scene, so that sounds like a lot of work.
A pure CPU emulator on a Raspi CM5, bare metal, without Linux, is something I'd find almost interesting.

[Will James]

What are the difficulties, do you know where you read about it? I just assumed it hadn't been done because it would require a bit of a re-write I would be very interested to know if there was something that was going to be a show stopper... The thing is once you have the hardware interface the rest is just software so a non Linux version would be a natural update to go for... I wasn't an expert when I began in February so I'm do it all incrementally as I learn. The obvious next step for me or someone else would be an EMU68 version.

[Peter]

If I remember correctly, there was mention of the GPIO sitting behind PCIe making things difficult. I have little doubt it will somehow be doable - but when the much more active Amiga scene has not accomplished it yet, that certainly sounds like much work.

[bwinkel67]

...for me what makes the QL PiStorm a better option is that it is going to give my actual QL hardware, that has a lot of sentimental value, a new lease of life...

I also think there is a slight difference between the emulation in a PiStorm and a software emulator written for Windows or Linux, isn't there? You are emulating the CPU but then are trying to interface with existing hardware through the RaPi (and a CPLD?), so it straddles that line a bit. It's definitely not like using an authentic 68K CPU to build a system, and a closer facsimile is going the FPGA/CPLD route, but I think the PiStorm approach sits in between a software emulator and FPGA/CPLD.

[XorA]

Okay, the microdrives are point I understand. For me they always were good riddance and unused for over 30 years, so I didn't consider.

It would probably not too hard to make microdrive work on a Pi connected to GPIO port. If someone was particularly driven!