Search found 18 matches

by SKS1
Fri May 07, 2021 1:18 pm
Forum: 32-bit acorn software: other
Topic: Risc OS and malloc in assembler
Replies: 7
Views: 141

Re: Risc OS and malloc in assembler

Eric, when your code is running, you will need to increase the *current* slot - the *next* slot is not relevant to your process.
by SKS1
Wed May 05, 2021 11:22 am
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Always get RISC OS to set up the system for you as suggested, either by changing first to the best-match mode (one with same bpp, at least as wide and deep as your desired mode) and changing as few VIDC registers as needed, or use a custom mode module. You can't assume that there will be a contiguou...
by SKS1
Wed Apr 28, 2021 12:57 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

I'd forgotten that the palette might be written at VSync because of flashing colours (good old BBC Micro heritage).

Try using SWI OS_Byte 9,0 to force the first colour to be displayed without flashing.
by SKS1
Wed Apr 28, 2021 12:00 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Just check the IOC IRQ Status Register A for VSync - if it's set, clear it using IOC IRQ Clear register and just return from interrupt after calling your VSync handler. Pass everything else on to the old IRQ handler.
by SKS1
Tue Apr 27, 2021 8:11 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

To use OS_Word 12, you need to pass the address of a parameter block containing five bytes in R1, see

https://www.riscosopen.org/wiki/documen ... _Word%2012

You are presumably aware on early VIDC that you can't independently set R,G,B for all 256 colours?
by SKS1
Tue Apr 27, 2021 3:49 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Does the palette persist if you set it up using the OS?
by SKS1
Fri Apr 09, 2021 11:23 am
Forum: off-topic
Topic: Vaccination Tales
Replies: 61
Views: 2082

Re: Vaccination Tales

I too am a member of the zero side-effects from AZ camp.
by SKS1
Thu Apr 08, 2021 2:20 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

OS lives in ROM, 'up there'. Bear in mind, as others have sagely noted before, that this bash-the-devices approach is limited to a subset of real RISC OS systems!
by SKS1
Thu Apr 08, 2021 2:09 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Yes, physical addresses as seen by MEMC begin at zero. As its DMA registers can only access the bottom 512KB of physical memory, zero was an easy choice for the start of display physical memory. I think that Vstart/Vend/Vinit are only set on MODE change and not on OS_ChangeDynamicArea, so set up you...
by SKS1
Thu Apr 08, 2021 1:50 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Remember that the DynamicArea API deals with user-addressable memory (on pre-ARMv3 this is always below &02000000); MEMC DMA registers deal with physical memory, starting at zero. RISC OS with MEMC always accumulates enough contiguous physical pages at physical memory zero to accommodate the dis...
by SKS1
Tue Apr 06, 2021 11:01 am
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Your program doesn't see the same memory map as the MEMC DMA, which doesn't go through any address translation. If you insist on trying to write to physical memory, you need to add &02000000 to your addresses and access it in a privileged mode. Easier is to write to the memory-mapped copy of scr...
by SKS1
Mon Apr 05, 2021 4:35 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Yes, change:

mov r1,#0x3600000
add r0,r0,r1
mov r1,#0x3600000
str r0,[r1]

to

mov r1,#0x3600000
add r0,r0,r1
str r0,[r0]

Edit: MEMC is not attached to the data bus - data for registers is taken from parts of the address.
by SKS1
Mon Apr 05, 2021 4:13 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Try setting Vinit to zero and incrementing it *slowly* - you should see the current screen contents scroll.
by SKS1
Mon Apr 05, 2021 4:04 pm
Forum: 32-bit acorn software: other
Topic: read vptr value
Replies: 83
Views: 1893

Re: read vptr value

Looks like you are trying to set up DMA from a virtual address - this is not possible. MEMC performs DMA for VIDC from physical addresses, so your Vinit needs to be the physical address (zero-based) of the pages to which you are writing in your program. By adding in such a large number to &03600...
by SKS1
Sun Feb 28, 2021 11:07 am
Forum: 32-bit acorn hardware
Topic: "Rumours have it" - unsubstantiated eBay claim
Replies: 10
Views: 790

Re: "Rumours have it" - unsubstantiated eBay claim

Did the a410 hit production?
I never saw an A410 at Acorn in 87/88, and we'd received early production A4x0/1s by late 88, though they took a while to get to market ISTR.
by SKS1
Tue Sep 22, 2020 7:55 pm
Forum: other events + general event chat
Topic: Stuart Swales, ex-Acornsoft, online at ROUGOL, Mon 21st Sept 2020
Replies: 7
Views: 933

Re: Stuart Swales, ex-Acornsoft, online at ROUGOL, Mon 21st Sept 2020

I am more convinced that it was an early View Professional and that Acornsoft just wanted it to fit with the well-established View branding - Rob would know! Sadly lost touch
by SKS1
Tue Sep 22, 2020 3:48 pm
Forum: introduce yourself
Topic: Hello from Highland Perthshire
Replies: 6
Views: 477

Hello from Highland Perthshire

Hi all - I'm Stuart Swales Acornsoft Languages; Acorn Arthur / RISC OS 2; Colton Software PipeDream & Fireworkz Now semi-retired halfway up a hill, with a wet piece of string to connect to the Interwebs SKS1 was my user id on the IBM 370/165 at Uni Fascinating to see that so much interest persis...

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