4K resulution

Hello,

Is it possible (or planned) to implement the 4k resolution (3840×2160) support in the RPCEmu?

Have you tried AnyMode from http://www.pi-star.co.uk/anymode/ – that might do it.

RPCEmu does support 4K for me @ 256 colours (that’s all you are going to fit in the extended 8MB VRAM; this is using the Generic MDF). Even though it’s virtual, you still need to fake the required bandwidth limits. Read the bit about configuring more VRAM in https://www.marutan.net/rpcemu/manual/

Running VRPC with RO5x – you can drag screen memory out to 32Mb.

Seem to remember that there was some sort of software block added in RO5 – had to reduce screen updates to a very low value.

VRPC != RPCEmu, Colin. I would suggest that RPCEmu is emulating the Risc PC hardware more closely. There is a) only a 16MB slot in physical address space for the VRAM in a Risc PC and b) not all the required address lines end up at the VRAM slot, limiting potential VRAM module size to 8MB. See page 2-25 of the Risc PC TRM.

[Edit: Though http://www.virtualacorn.co.uk/products/vrpcse.htm still only claims ‘Support for screen modes up to 8Mb in size’]

[Edit #2: Though if you set VRAM size to zero in the emulator’s Config, then you can drag screen size up past 8MB. Would that help with deeper large screens? I do not know.]

I think the A7000 model (in contrast to the RiscPC model) should be able to give you 16 MiB of addressable video RAM. Not tried for myself, my screen is only 4K, and I always have RPCEmu in a window, so it’s currently 2560×1440 for me.

Has anyone built a 4Mb or 8Mb VRAM card for the RPc – now we have LCD monitors?

What is the max Ram that both the Emulators emulate – 2 lots of 256Mb doesn’t seem to work?

Has anyone built a 4Mb or 8Mb VRAM card for the RPc

Won’t work. It’s not an issue of how much memory is available (though they’re may well be insufficient address lines in hardware – above suggests an 8MB limit), it’s a question of how fast you can spew out the pixels.
A screen of, say, 800×600 is 480,000 pixels. It 16 million colours BGR, that’s 1,920,000 bytes (or all of the available VRAM). It needs to read 2MB to output 480K pixels 60 times a second. The pixel clock will be about 40MHz.
FullHD is 1920×1080 which is 2,073,600 pixels, requiring 8,294,400 bytes and a pixel clock of about 148MHz.
The VIDC2 maxes out at 110MHz according to the PRM, so higher rates and resolutions aren’t physically possible.

What the extra memory could be used for is bank switching an SVGA frame at 32bpp, for instance.
As for bigger displays, the VIDC2 can, but you’d need to drop the colour depth to both fit memory and not overrun the bandwidth.

You ought to get 1280×1024 in 256 colours. You might manage something like 1360×768 in 64K (just fits!) but you’d need a monitor happy with a lower (55Hz?) frame rate. And that may be your problem – will your monitor lock on to those lower frame rates?

Indeed, the help for RPCEmu says in bold “Warning: DO NOT DO THIS ON REAL HARDWARE it could damge it” (sic).

And from the Risc PC TRM: “Although the Risc PC platform is designed initially to support only 1 or 2 MB of VRAM there may be specialist applications for larger modules in the future. Although these would be unlikely to offer larger resolutions or colour depths due to system bandwidth limitations, it may be possible for example to provide a secondary frame buffer in a second 2 MByte bank.”

Risc PC goes in bin. I should chainsaw mine [I say this to wind Paolo up].

What is the max Ram that both the Emulators emulate – 2 lots of 256Mb doesn’t seem to work?

The physical address space for DRAM in the Risc PC is 256MB.

This is also true for the ARM 7500FE: “The DRAM interface can directly drive four banks of DRAM to give a maximum of 64MB in each DRAM bank”

Hey, send me your motherboard instead. I think the battery has done mine in. Then I can get the thing running again (if the harddisc even works) to see if there’s any old crap worth salvaging.

But, yeah, the only reason for discussing a RiscPC in 2022 is because that’s what our emulator is.

Physical machines? Can have it’s arse handed to it many times over by a £5 Pi Zero.

<mic drop>

Where was the ‘Kinetic RPc’ fast memory mapped too?

Anyhoo, back on topic.

If you set an A7000+ in config (no VRAM) and then amend the Bandlimit line to have args 2000000 2000000 2000000 2000000 that’ll give you far more than the hardware can (don’t add more digits: the Bandlimit command multiplies all these integers by 1000).

This ought to allow 16-bit display at 4K (well, it did for me using RPCEmu 0.9.4). But the actual display in a window seems somewhat wonky. I have no icon bar and menus appear in two places… But then again it does seem to work in full screen mode. YMMV.

Where was the ‘Kinetic RPc’ fast memory mapped too?

No idea, honestly. It’s likely that the CPU on the daughterboard and IOMD on the motherboard have different views on the DRAM there. As far as I’m aware, RPCEmu doesn’t emulate a Kinetic, so bumping up the memory in rpc.cfg above 256MB wouldn’t do anything.

Whats the max DRAM for the one slot of the A7000+ ?

Whats the max DRAM for the one slot of the A7000+ ?

It would have been max 128MB EDO DRAM for that slot if memory serves.

Here goes: https://archive.org/details/AcornUser183-Jul97/page/n25/mode/2up but somehow didn’t spot that one memory bank was soldered on…

Physical machines? Can have it’s arse handed to it many times over by a £5 Pi Zero.

Which gives me an idea, purely for those after a hit of nostalgia…

How about someone (probably with more experience at low-level hardware design than I would claim to have) comes up with a board that fits into the back of a RPC or A7000 case (if memory serves the motherboards were interchangeable) which has an onboard USB hub, audio chip and Ethernet interface, with the audio and network connectors brought out to the correct place on the back panel, HDMI port extended to where the VGA socket was, and the serial / parallel sockets replaced with USB ports? Possibly with adding USB to SATA ports for hard drives / CD-ROMs and maybe even a USB to floppy interface for the full 3.5" floppy disk experience? Just add one Pi Zero and retrofit the whole board into your RiscPC or A7000 case?

Of course podules probably would be a non-starter, but unless you had specialist hardware (DMI-50S, MidiMax, RiscTV anyone?) this probably wouldn’t be an issue. It would just be kinda nice to have a RISC OS machine in a RISC PC (or A7000) case.

Any takers?

The PiPOD kind of does that – it allows you to mount a RPi inside a spare podule slot, powering the Pi from the host’s PSU. But all the ports are exposed via the podule faceplate, not via the usual case connections.

http://www.riscosbits.co.uk/pipod.htm

The VIDC2 maxes out at 110MHz according to the PRM, so higher rates and resolutions aren’t physically possible.

Unfortunately that is what they turned out to be capable generally. All the pre-launch documentation stated 1600×1200×8bpp would be supported, but literally on the day of the launch at Lancaster Hotel it was knocked down to 1280×1024×8bpp.

Luckily I was able hand pick the Risc PCs I had for work and home, so got ones with VIDC2s capable of 1600×1200 which I used right up until ViewFinder came along an bumped me up to 32bpp at that resolution, and later with a better graphics card 2048×1536×32bpp – which was the same as the Iyonix could do out of the box.

Luckily I was able hand pick

How do you tell the difference?

How do you tell the difference?

Suck it and see, I imagine.

Hey, send me your motherboard instead. I think the battery has done mine in. Then I can get the thing running again (if the harddisc even works) to see if there’s any old crap worth salvaging.

I managed to transfer all my stuff from the IDE drives by hooking them up to a USB to IDE adapter plugged into a Raspberry Pi running RISC OS, and connected to a Samba share on a *nix server. No need for real hardware.

The stuff on the SCSI drive? That needed a working RISC PC set up. Fortunately one of mine still worked.