RPCemu RO3.7 with >2MB VRAM

Been having a play around with RPCEmu. Have installed both versions, the “classic” RO3.7 and the latest version.

First thing I noticed in the 3.7 ROM is that you can’t extend the VRAM beyond 2MB, ie what would have been possible in a physical RiscPC. However the newer version allows sufficient VRAM to run full-screen in Full HD mode (1920×1080).

Now I have a number of RO apps rescued from the late 1990s that aren’t “32-bit safe”, so the question is, is it possible to patch the ROM to allow more VRAM (given that it’s a virtual machine and there’s no hardware limitations), and thus allow me to run a 3.7 emulation at 1920×1080 in 24bpp?

If you have 2MB VRAM selected, RPCEmu will attempt to patch the ROM to support 8MB VRAM, which is what the physical RiscPC could have supported. It does imply that in the radio button label.

Have a look in rpclog.txt, you should find something along the lines of:

romload: Loaded 'ROM371' 4194304 bytes
romload: Total ROM size 4 MB
romload: ROM patch applied: 8MB VRAM RISC OS 3.71

You should be able to show the memory is there by dragging the screen size allocation in Switcher.

Ok, I checked in the memory window, and you can drag the screen memory out to 8MB. However you can’t select 1920×1080 at 16M colours, it drops down to 800×600. The RISC OS 5 version lets you run Full HD at 24bpp.

I vaguely recall something about a bandwidth limit somewhere that needed setting up?

Yup. See the other thread: https://www.riscosopen.org/forum/forums/10/topics/17622#posts-136915

Thanks, that works. I knew I’d seen it somewhere.

Was just running RO3.7 in emulation on my laptop’s Full HD screen (AMD Ryzen 3 with 20GB RAM). One thing I did notice, it reminded me just how good the font rendering is on RISC OS. Yes, Windows now has Cleartype (which is pretty decent) but it doesn’t seem to be a patch on what RISC OS had over 30 years ago.

So yeah, I’d say the ‘killer feature’ on RISC OS is / was the quality of the on-screen font rendering.

Yes. I have bad eyes. on Windows it hurts and is difficult to read, while on RISC OS it is just fun to read.
Seems the font rendering of RISC OS is still unbeaten.

What is the max res/col now found for RPCemu?

Since it is a emulator – what is the possibility of increasing DRAM to 512 or more?

With ref to the A310 emulator – Is it possible to increase screen memory?

Thanks to the one’s who have developed the Emulators.

I can run Full HD resolution at 24bpp on the laptop, or 1680×1050 on the desktop (that’s right, my laptop’s screen is higher resolution than the desktop – the desktop PC has an Iiyama monitor from 2008, the laptop is about 3 months old).

Unsure whether it could do 4K resolution, however if it can do 4K at 24bpp on a smaller (laptop-sized) display then set the Xeig/Yeig to 1 and you’ve got a 180ppi ¹ display.

¹ PPI – Pixels Per Inch, as opposed to DPI (Dots Per Inch) which refers to the mechanical resolution of an output device, ie my Epson photo printer prints at 6,000dpi, but the input resolution is 300dpi. Nothing to do with mis-sold PPI.

What is the max res/col now found for RPCemu?

RPCEmu supports both 1920×1080 @ 32 bit depth and 4K @ 256 colours for me on a Risc PC (that’s all you are going to fit in the extended 8MB VRAM of a Risc PC) once you have given the magic Bandlimit incantations. I found it a bit wonky doing 4K @ 16 bit depth emulating A7000+ (which doesn’t have VRAM). YMMV.

what is the possibility of increasing DRAM to 512 or more?

Little prospect, unless you want to take on building another emulator! There isn’t enough space in the physical address map of a Risc PC to add more than 256KB memory to the motherboard given IOMD.