Search found 83 matches

by Phlamethrower
Tue Oct 09, 2018 9:02 pm
Forum: programming
Topic: Ray Traced Spheres
Replies: 26
Views: 820

Re: Ray Traced Spheres

Nice!

One easy optimisation: Move line 130 down to 165 (or just get rid of the pp variable completely, since it's only used once)
by Phlamethrower
Mon Oct 08, 2018 12:32 pm
Forum: general
Topic: A new article about the first ARM processors
Replies: 9
Views: 594

Re: A new article about the first ARM processors

A few factual mistakes: "RSUB R1, R0, R0 shl 6" - the correct mnemonic for reverse subtract is RSB. I don't think I've ever seen an assembler which accepts "RSUB". "You can load only 12 bits at a time, although the constant can be inverted and shifted." - you can only load 8 bits at a time, since 4 ...
by Phlamethrower
Fri Sep 21, 2018 5:15 pm
Forum: emulators
Topic: RPCEmu 0.9.0 and Macs - beta testers wanted
Replies: 52
Views: 2120

Re: RPCEmu 0.9.0 and Macs - beta testers wanted

There was a "mailing list glitch" recently, so if you don't get any feedback in the next day or two then it's probably worth trying to send it again (or a test message, at least)

http://www.riscos.info/index.php?title= ... itch_fixed
by Phlamethrower
Mon Sep 17, 2018 12:13 pm
Forum: general
Topic: Remarkable videos recently posted on Youtube
Replies: 180
Views: 18839

Re: Remarkable videos recently posted on Youtube

davidb wrote:
Tue Sep 04, 2018 1:50 pm
The Centre for Computing History has put up a few interesting videos related to ARM recently. Here's one that I found quite intriguing: Historic ARM Presentation to Apple Computer - 1992.
Interesting to learn about the genesis of some of the ARM6's features - thanks for bringing it up!
by Phlamethrower
Wed Sep 12, 2018 12:37 pm
Forum: general
Topic: 4corn update 12/09/2017 - 8 Unpublished/draft manuals
Replies: 1
Views: 134

Re: 4corn update 12/09/2017 - 8 Unpublished/draft manuals

4corn update 12/09/2017
I think you've been spending too long looking at old documents - it's 2018, not 2017!
by Phlamethrower
Tue Sep 11, 2018 9:19 pm
Forum: other vintage computer hardware, software and games
Topic: Acorn games on other platforms
Replies: 16
Views: 502

Re: Acorn games on other platforms

There's an Iconbar thread with a few examples of Arc games that made it to other platforms. You might need to do a bit of digging to get working URLs, though. https://www.iconbar.com/forums/viewthread.php?threadid=11135&page=3#110631 There's also 1992 Olympics tie-in Quest for Gold, which appeared o...
by Phlamethrower
Mon Sep 03, 2018 9:02 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 758

Re: BBC BASIC integer arithmetic

Somebody knowledgeable about the limitations of floating-point arithmetic wouldn't find them surprising, but they ought to be very surprised by what Acorn's BASICs do with my example! Someone familiar with Acorn BASIC wouldn't be surprised by Acorn BASIC's behaviour either. Horses for courses :) Th...
by Phlamethrower
Mon Sep 03, 2018 6:47 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 758

Re: BBC BASIC integer arithmetic

there are a great many number of unexpected and potentially dangerous things that can go wrong with traditional floating point arithmetic as well. Sooner or later the programmer has to learn that these issues exist. Can you give an example? If you're thinking of the well-known issues associated wit...
by Phlamethrower
Mon Sep 03, 2018 1:22 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 758

Re: BBC BASIC integer arithmetic

Can anybody offer an explanation for why Acorn/Sophie might have felt that such a (superficially) unhelpful behaviour is desirable? The best I can think of is that it was born from a desire to emulate the behaviour of the CPU. The 6502 integer addition/subtraction instructions wrap, therefore BASIC...
by Phlamethrower
Fri Aug 24, 2018 12:46 pm
Forum: other vintage computer hardware, software and games
Topic: Calling conventions for functions on various architectures?
Replies: 18
Views: 444

Re: Calling conventions for functions on various architectures?

My understanding was that on APCS at least 4(?) function arguments/parameters were passed in registers. Yes, the basic approach is that the first four (integer) values are passed in registers, with the rest being pushed to the stack. But there are many different variants of APCS, both for 32bit and...
by Phlamethrower
Wed Aug 22, 2018 11:02 pm
Forum: programming
Topic: Dispatch tables...
Replies: 5
Views: 311

Re: Dispatch tables...

I haven't looked at the algorithms in any detail, but for current RISC OS versions: SWIs number -> handler lookup is via a hash table (mapping to handlers for each SWI chunk), except for kernel SWIs which use a lookup table for each SWI number Interrupt handlers and vector claimants use arrays (inde...
by Phlamethrower
Mon Aug 20, 2018 12:42 pm
Forum: emulators
Topic: [SOLVED] RPCEmu and Hard Disc images
Replies: 3
Views: 338

Re: RPCEmu and Hard Disc images

I don't understand the underlying issue, all I know is that real hard disc images need tweaking a bit to work in RPCEmu.

https://www.iconbar.com/forums/viewthre ... adid=12152
by Phlamethrower
Mon Aug 20, 2018 12:15 pm
Forum: software
Topic: Unreleased games
Replies: 41
Views: 2396

Re: Unreleased games

Perhaps someone with more time than I, would like to try it and come up with a list of what the keys do. Not sure if it's true for all versions, but the VOTI release of the designer had a section of the BASIC program that contained a listing of the controls (probably accessible in-editor by pressin...
by Phlamethrower
Sun Aug 19, 2018 10:05 pm
Forum: software
Topic: Unreleased games
Replies: 41
Views: 2396

Re: Unreleased games

On the subject of "Unreleased games", were Stunt Racer 2000 Extra Tracks Series 3 or the Stunt Racer 2000 Track Designer ever released? I have both, which could probably be released if someone is prepared to test them to confirm they work. I don't know if the track designer was ever officially rele...
by Phlamethrower
Sat Aug 18, 2018 9:01 pm
Forum: programming
Topic: BBC BASIC INTERPRETER differences between versions on Acorn/RISC OS machines (links)
Replies: 3
Views: 212

Re: BBC BASIC INTERPRETER differences between versions on Acorn/RISC OS machines (links)

RISC OS 5 Improvements to BASIC 5: (BASIC V) BASIC 1.32 -: https://web.archive.org/web/20111227182632/http://www.iyonix.com/32bit/BASIC.shtml (Archive copy) (I'm not sure what other improvements were made in Risc OS Open..) Conveniently, the "open" part of the name means you can just check the CVS ...
by Phlamethrower
Sat Aug 18, 2018 12:21 pm
Forum: programming
Topic: Floating point representation examples?
Replies: 8
Views: 499

Re: Floating point representation examples?

RISC OS BASIC contains code for converting to and from 5-byte and IEEE double precision - if you can decipher the sources. https://www.riscosopen.org/viewer/view/castle/RiscOS/Sources/Programmer/BASIC/s/Stmt2?rev=1.18#l1842 The code at lines 1856-1865 convert 5-byte floats to double precision, lines...
by Phlamethrower
Thu Aug 16, 2018 12:21 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 314
Views: 8542

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

One difference between this and RISC OS 3.71 (which is what I have running in RPCEmu) is that in RISC OS, setting the eigen value to values other than 1 alter the drawing coordinates but the mouse coordinates are NOT changed. In Brandy, both are changed keeping the mouse in step with the drawing. I...
by Phlamethrower
Wed Aug 15, 2018 4:19 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 314
Views: 8542

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

If you're after a way of using arbitrary modes, it might be worth improving Brandy's support for the extensions to the MODE statement that were introduced in RISC OS 3.5: MODE <n> If the unsigned value of N is less than 256, it's treated as a mode number. Otherwise, it's treated as a pointer to a mo...
by Phlamethrower
Tue Aug 14, 2018 7:22 pm
Forum: software
Topic: !Tracker music software
Replies: 22
Views: 594

Re: !Tracker music software

The one I'm most familiar with is APTracker, by Andrew Pepperell (but based on work by Hugo Fiennes, Fabrice Mercier, and Matt Farrow, according to the docs). Although it presents a wimp interface by default, you can switch to the full-screen edit/play mode by adjust-clicking the iconbar icon. You c...
by Phlamethrower
Sun Aug 12, 2018 10:26 am
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 314
Views: 8542

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

Don't forget that RISC OS has OS_Byte 112/113 for controlling screen banking. It's not quite the same functionality as *REFRESH, but if the intention is to keep Matrix Brandy programs compatible with RISC OS BASIC (and vice-versa) then supporting those calls would be useful. Richard Russell's BASIC...
by Phlamethrower
Sun Aug 12, 2018 12:55 am
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 314
Views: 8542

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

Don't forget that RISC OS has OS_Byte 112/113 for controlling screen banking. It's not quite the same functionality as *REFRESH, but if the intention is to keep Matrix Brandy programs compatible with RISC OS BASIC (and vice-versa) then supporting those calls would be useful. Richard Russell's BASICs...
by Phlamethrower
Sat Aug 11, 2018 1:44 am
Forum: hardware
Topic: Which Raspberry Pi to purchase?
Replies: 4
Views: 368

Re: Which Raspberry Pi to purchase?

I'd puchase https://thepihut.com/products/raspberry-pi-3-model-b-plus though looking at the RISC OS Open site there were early internet connection issues with the Pi 3B+? "were", past tense. The 3B+ uses a new LAN chip, and we didn't have a driver for it until a few weeks after the 3B+ was released...
by Phlamethrower
Thu Aug 09, 2018 6:17 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 314
Views: 8542

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.8 released

I wonder if Acorn went down the different road of using a palette only when the display is itself paletted, and using RGB values if not. Pretty much, yeah. In true colour modes, the memory used by the palette is used for defining the gamma table instead - which means that COLOUR L,R,G,B will actual...
by Phlamethrower
Tue Aug 07, 2018 7:28 pm
Forum: software
Topic: Unix for Archimedes
Replies: 21
Views: 709

Re: Notes on ARX, not a Unix

I was aware of this reason for implementing the SWP instruction in hardware, but something else I once read was that LDM or STM instructions had previously been used as a mechanism for implementing mutexes in an atomic way. Anyone got any idea how that would've worked (or even where I read it)? Tha...
by Phlamethrower
Sat Aug 04, 2018 3:05 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

Ah, there is this documentation, outside of the VC++ docs, which doesn't mention the duplication of parameters. https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/x64-architecture#span-idcallingconventionsspanspan-idcallingconventionsspanspan-idcallingconventionsspancalling-conventio...
by Phlamethrower
Sat Aug 04, 2018 2:56 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

Because Microsoft says so, that's why. Are you sure that's not specific to Visual C? There's no mention of it that I can see in the ABI documentation, so it's not clear to me that GCC should, or does, abide by it. In case you're tempted to suggest I compile BBC BASIC using Visual C, note that it do...
by Phlamethrower
Sat Aug 04, 2018 11:21 am
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

Because everything gets passed in as a double, the compiler (if it's following MS's rules) should populate both the int and float CPU regs. Why? Because Microsoft says so, that's why. Unprototyped functions: For floating-point values only, both the integer register and the floating-point register w...
by Phlamethrower
Fri Aug 03, 2018 10:51 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

But it won't work if you have a mix of ints and floats because you're duplicating the full set of arguments in both the int and float registers. It will in the case of the Windows ABI (which is what that code is targetting). The way things work in Windows is fundamentally different from the way the...
by Phlamethrower
Fri Aug 03, 2018 6:00 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

I can see that it would work in some situations, but I'd be surprised if it works for anything other than the most trivial cases (e.g. all parameters are either integers or floats). Bearing in mind that 'integers' includes 'pointers' (they are passed the same way in every ABI I know of) that covers...
by Phlamethrower
Fri Aug 03, 2018 1:23 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBC BASIC for SDL 2.0 v0.18a released
Replies: 36
Views: 1820

Re: BBC BASIC for SDL 2.0 v0.18a released

The idea of passing parameters in two places seems like a clever workaround. It quite literally came to me in the middle of the night. Persuading a C compiler to do it was challenging, and relies on a non-standard GCC extension (nested functions). I found it necessary to disable optimisation for th...