Search found 36 matches

by zolbatar
Wed Aug 21, 2019 10:13 am
Forum: wanted
Topic: A3000 thru RiscPC
Replies: 6
Views: 458

Re: A3000 thru RiscPC

With a mouse and working keyboard I am interested. I have a poorly A4000 with track damage if you fancy a project as well 😉

I tried fixing myself but I'm struggling to solder with my eyes!
by zolbatar
Wed Aug 21, 2019 9:24 am
Forum: wanted
Topic: A3000 thru RiscPC
Replies: 6
Views: 458

Re: A3000 thru RiscPC

By bizarre coincidence I just posted up my A3020 for sale. https://stardot.org.uk/forums/viewtopic.php?f=8&t=17735 Not too far from Nottingham to Cambridge if you want to pop down! :D Kind Regards Andy I would have preferred a machine with a mouse, and little concerned with the keyboard not being f...
by zolbatar
Wed Aug 21, 2019 8:03 am
Forum: general
Topic: RISC OS presentation to my Linux user group
Replies: 7
Views: 676

Re: RISC OS presentation to my Linux user group

roland wrote:
Tue Aug 20, 2019 10:40 pm
In theory it must be possible to port LibreOffive or OpenOffice to RISC OS because the source files are available. The main questions is: who wants to start that project :?:
I'm not sure we would want that though. It wouldn't fit the RISC OS look & feel. It would however tick another box!
by zolbatar
Tue Aug 20, 2019 5:24 pm
Forum: wanted
Topic: A3000 thru RiscPC
Replies: 6
Views: 458

A3000 thru RiscPC

Does anybody have a working, preferably good condition 32 bit machine for sale? A3000 would be nice, but anything up to RiscPC would be considered.

Prefer to collect. I'm Nottingham based.
by zolbatar
Tue Aug 20, 2019 4:18 pm
Forum: other vintage computer hardware, software and games
Topic: Hardware for retro 3d stuff
Replies: 2
Views: 347

Re: Hardware for retro 3d stuff

Planar graphics are painful! Reminds me of programming EGA back in the day!

16 colour us definitely no fun for shading and the VIDC palette isn't great.

I want to stick in the Acorn world I think. I have been thinking of investing in a RiscPC but feel the Pi is similar enough in some ways.
by zolbatar
Tue Aug 20, 2019 12:16 pm
Forum: other vintage computer hardware, software and games
Topic: Hardware for retro 3d stuff
Replies: 2
Views: 347

Hardware for retro 3d stuff

I'm playing around with some 3D stuff, and had some pretty nice gouraud shaded 3D stuff going on RISC OS on my Pi. It looks great and performs excellently using VFP instructions but it's hardly retro! I want get something similar going on an older machine... I have my Master with Pi co-pro which cou...
by zolbatar
Sun Aug 18, 2019 12:33 pm
Forum: general
Topic: RISC OS presentation to my Linux user group
Replies: 7
Views: 676

Re: RISC OS presentation to my Linux user group

I'm not sure I converted anybody yet but there was interest. The boot speed impressed as did the ease of getting coding.

It's a difficult sell though with the lack of certain categories of software, such as real presentation software for instance. I used Linux to present..
by zolbatar
Fri Aug 16, 2019 12:43 pm
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1174
Views: 132026

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)

Thanks for the advice. Ordered a Zero WH.

I'm going to try and port some of my RISC OS 3D code over and see how much I can eek out of my 128 for graphics. I know right now that video write speed will be the bottleneck obviously.

Daryl.
by zolbatar
Fri Aug 16, 2019 10:34 am
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1174
Views: 132026

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)

Just a quick question, I had a Pi 3B+ on my PiTubeDirect but reused it for regular RISC OS stuff. Is the Pi Zero still good for use? I presume not wildly slower than the 3B+? I don't mind buying either as they are both cheap enough, but just feels "neater" having a smaller daughterboard inside the c...
by zolbatar
Thu Aug 15, 2019 8:08 am
Forum: general
Topic: RISC OS presentation to my Linux user group
Replies: 7
Views: 676

RISC OS presentation to my Linux user group

So tonight I'm doing an Acorn history and RISC OS presentation and demonstration to my Linux user group (nottslug).

I'm not sure if I'll convert anybody but I'm sure it'll be interesting!
by zolbatar
Wed Aug 14, 2019 11:50 am
Forum: programming
Topic: !GCC on RISC OS with -O2 and cexpf
Replies: 5
Views: 411

Re: !GCC on RISC OS with -O2 and cexpf

I would highly recommend for performance that you use fixed point representation for your matrix maths, and use a sine table to lookup sines/cosines rather than calculating them with sinf()/cosf(). Also, remember there are some nice trig identities you can use to avoid multiplications: e.g. sin A *...
by zolbatar
Wed Aug 14, 2019 11:19 am
Forum: programming
Topic: !GCC on RISC OS with -O2 and cexpf
Replies: 5
Views: 411

Re: !GCC on RISC OS with -O2 and cexpf

It's the latest version from !Packman.

I don't actually do any complex number stuff myself, it seems to be a compiler optimisation. Some online searching suggests changing to doubles and it no longer does it. I have gcc to leave the intermediate assembler so I will take a look at it.
by zolbatar
Wed Aug 14, 2019 8:37 am
Forum: programming
Topic: !GCC on RISC OS with -O2 and cexpf
Replies: 5
Views: 411

!GCC on RISC OS with -O2 and cexpf

In my 3D matrices code there are a bunch of trig functions doing rotation. If I run GCC/make normally, I get a working executable, but if I use any optimisation flags such as -O1 then I get a link error with it unable to find cexpf. A google suggests that GCC is doing some clever optimisation where ...
by zolbatar
Tue Aug 13, 2019 2:11 pm
Forum: emulators
Topic: RPCEmu real speed
Replies: 3
Views: 795

Re: RPCEmu real speed

flibble wrote:
Tue Aug 13, 2019 2:04 pm
Nope.
Cheers. It's actually useful that it doesn't but I am working on some code I wanted to test. I'll have to get willing volunteers to speed check it for me!
by zolbatar
Tue Aug 13, 2019 10:40 am
Forum: emulators
Topic: RPCEmu real speed
Replies: 3
Views: 795

RPCEmu real speed

I might be being dumb, ArcEm of course runs at native speed, but RPCEmu runs as fast as possible. This is great when doing things like compiles (faster than the Pi) but I want to test whether my stuff will run at a reasonable speed on a real machine. So, does RPCEmu bother at all trying to be realis...
by zolbatar
Tue Aug 13, 2019 9:12 am
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Re: Retro style low-res or not?

Thanks.

You do have me wondering just how realistic it is to do this on a Master. Possibly, but would be a ton of work!
by zolbatar
Tue Aug 13, 2019 7:49 am
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Re: Retro style low-res or not?

Is it possible to upload videos here or do I need to post to something like YouTube and share a link?
by zolbatar
Sat Aug 10, 2019 7:52 pm
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Re: Retro style low-res or not?

I'm currently considering some mixed wireframe and filled polygon Outrun style (the art style as well as game).

Not TOO difficult and MAY look retro in a fun way.
by zolbatar
Fri Aug 09, 2019 12:39 pm
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Re: Retro style low-res or not?

That sounds like an insane challenge!! Video write speed alone would cause problems, never mind trying to do floating point on an 8 bit machine! Lots of tricks with integer maths and lookup tables :-)
by zolbatar
Fri Aug 09, 2019 12:35 pm
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Re: Retro style low-res or not?

Why not make it work in more than one screen mode? I suppose that is a bit obvious, as a vector game it shouldn't be too difficult. For pixel art style, it isn't quite so easy. As I'm targeting the Pi rather than trying to do it for my Master I have plenty of power to play with, so don't need to ha...
by zolbatar
Fri Aug 09, 2019 12:27 pm
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 870

Retro style low-res or not?

I'm having a go at a simple 3D "thing", a little descent in style but using flat shaded polygons (and maybe wireframe, not decided yet). I started in assembler but quickly moving to use GCC, it's quicker and "fast enough". I've written all my own graphics routines including filled polygons. What's e...
by zolbatar
Sat Aug 03, 2019 11:32 am
Forum: software
Topic: !GCC compile speed
Replies: 1
Views: 353

!GCC compile speed

Is there any way to improve GCC compilation speed on a Pi? Would putting all source files on a single line help?

10 seconds feels an age these days!

I'm admittedly spoiled by the speed of BBC Basic and assembling.
by zolbatar
Thu Jul 18, 2019 6:29 pm
Forum: programming
Topic: RISC OS Arm assembly
Replies: 3
Views: 850

RISC OS Arm assembly

After failing to get my poorly A4000 working well enough to use I've decided to use my Pi instead for my pet project. I learnt ARM assembly in a few days and refreshed my BBC BASIC skills after a 20 year break. I have a vector based idea I want to play around with and spent the last week or so writi...
by zolbatar
Tue Jul 16, 2019 2:13 pm
Forum: software
Topic: Changing the 256 colour palette on Pi
Replies: 1
Views: 307

Re: Changing the 256 colour palette on Pi

Okay, I think it might be my code, working on it :-)
by zolbatar
Tue Jul 16, 2019 1:03 pm
Forum: software
Topic: Changing the 256 colour palette on Pi
Replies: 1
Views: 307

Changing the 256 colour palette on Pi

I've searched and read a million things and it's still not clear how to change the default 256 colour palette. I would like to know how to set it on the Pi and preferably RO 3 era machines. I don't want to use 24 bit colour. VDU 19,colour,16,red, green, blue just updates the colours I change to grey...
by zolbatar
Tue Jul 16, 2019 7:12 am
Forum: software
Topic: OS Version
Replies: 14
Views: 799

Re: OS Version

The code I've got will work on an RO 3 machine but on my RPi 3 it's doing a million random full screen width horizontal lines in about 2 seconds. That's around 8000 a frame, which is quick enough for what I need. Most of the time is spent writing to video memory and it's optimised to write 4 bytes a...
by zolbatar
Mon Jul 15, 2019 11:01 am
Forum: software
Topic: OS Version
Replies: 14
Views: 799

Re: OS Version

Thanks for all the help, I got my code to run - but ignored the FHLD routine. It basically dumps out all 256 colours by drawing a line from 0 to 1280 (or equivalent when writing direct to screen memory). BBC BASIC Plot - 501 fps BBC BASIC using OS_Plot - 287 fps BBC BASIC Screen memory write - 125 f...
by zolbatar
Sun Jul 14, 2019 9:42 pm
Forum: software
Topic: OS Version
Replies: 14
Views: 799

Re: OS Version

The fast line drawing stuff fails on RISC OS 3.11 as well, so I'm doing something wrong. Out of interest, how fast/efficient are the OS PLOT routines for things like lines and triangles? Back in the day I would always implement my own Bresenham's line drawing implementation or fill triangles (using ...
by zolbatar
Sat Jul 13, 2019 9:40 pm
Forum: software
Topic: OS Version
Replies: 14
Views: 799

Re: OS Version

Yes. There are a couple of kernel workspace locations which the routine writes to (which will generally be read-only from user mode), and on Archimedes machines if the screen is scrolled then some of the screen may be inaccessible from user mode. So apologies for being dumb, how do I get to be in S...
by zolbatar
Sat Jul 13, 2019 5:14 pm
Forum: software
Topic: OS Version
Replies: 14
Views: 799

Re: OS Version

Phlamethrower wrote:
Sat Jul 13, 2019 11:10 am
The OS's horizontal line routine should work - I've used it myself under RISC OS 5 (and I'm fairly certain the OS will be using it itself). Can you share your code?
In the documentation it says the ARM needs to be in SVC mode? Does it?