Search found 183 matches

by ctr
Tue Aug 07, 2018 10:28 pm
Forum: software: other
Topic: Enhanced mode 1 pictures
Replies: 108
Views: 12936

Re: Enhanced mode 1 pictures

I shouldn't have used the term 'speckling', I was meaning to refer to the 'noise' that Tom Seddon and Tricky referred to, where on some of their Beebs (but apparently not Masters?) some of the bits end up as random values, not 1s as expected. Which seems like a serious defect! It's not a problem in...
by ctr
Sun Aug 05, 2018 10:30 pm
Forum: programming
Topic: Beeb SOUND weirdness
Replies: 9
Views: 426

Re: Beeb SOUND weirdness

Cheers, with this clue I went looking in the MOS. Having calculated the 10-bit frequency period value to write to the chip (in &83D and &83E) the code at &ED6F adds in a constant channel fudge factor from a lookup table at &C441 . (Confusingly, the channel number is represented by a value in X betwe...
by ctr
Sun Aug 05, 2018 5:02 pm
Forum: programming
Topic: Beeb SOUND weirdness
Replies: 9
Views: 426

Beeb SOUND weirdness

When I play the same note on two different channels I get two different pitches. I've tried this on beebem, b-em and b2 with consistent results but not a real beeb. Can anyone reproduce it? It's surprising that these emulators all do this, but I'd also be surprised if a real beeb worked like this. T...
by ctr
Fri Aug 03, 2018 5:46 pm
Forum: programming
Topic: Beeb ENVELOPE documentation
Replies: 4
Views: 262

Re: Beeb ENVELOPE documentation

I certainly wasn't aware of that, and should anybody care neither BBC BASIC for Windows nor BBC BASIC for SDL 2.0 emulates the behaviour described here. In fact using them it isn't possible to generate, using ENVELOPE, an alternating tone with equal durations. Because the pitch envelope has an odd ...
by ctr
Fri Aug 03, 2018 4:02 pm
Forum: programming
Topic: Beeb ENVELOPE documentation
Replies: 4
Views: 262

Beeb ENVELOPE documentation

I was trying to create a simple envelope that alternated between two pitches but it was more trouble than I expected because there are a couple of errors in the BBC User Guide. I ended up using Audacity to look at the sound output to see exactly what was going on. To save anyone else the bother... T...
by ctr
Fri Aug 03, 2018 10:00 am
Forum: stardot.org.uk
Topic: Attachment types permitted
Replies: 9
Views: 485

Re: Attachment types permitted

may be should also allow Bitmap Image, as thats what BeebEm414 defaults to for capture screen for high scores! had to change it in paint prog to jPeg, but lost quality of pic :( On the menu in beebem select: File | Screen Capture Options | PNG Format then select: Options | Save Preferences and you ...
by ctr
Sat Jul 28, 2018 6:08 pm
Forum: software: other
Topic: Any short type-ins for unattended Beebs?
Replies: 143
Views: 7263

Re: Any short type-ins for unattended Beebs?

The perspective might not be quite right... 10REM ctr - spherical spiral 20MODE0 30REM number of steps: 40R%=2500 50H%=R%/2 60REM rotated towards viewer by: 70R=-PI/4 80U=COS(R):V=SIN(R) 90PROCP(4,0) 100FORI%=1TOR% 110PROCP(5,I%) 120NEXT 130END 140DEFPROCP(C%,S%) 150T=PI*(S%-H%)/R% 160C=COS(T) 170X=...
by ctr
Sat Jul 28, 2018 10:28 am
Forum: software: other
Topic: BBC Font
Replies: 7
Views: 481

Re: BBC Font

They are right at the start. Try this on a beeb. 10MODE4 20S%=&5800 30C%=&C000 40FORI%=0TO&2FF 50S%?I%=C%?I% 60NEXT Each char is eight bytes, one byte for each row, eight pixels in each byte. Most significant bit on the left, least significant on the right. Edit: This is true on a Model B; the Maste...
by ctr
Wed Jul 18, 2018 4:14 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2694
Views: 229368

Re: Worth Taking a Look At

Only 35 years or so left to wait. Isn't it 70 years after the death of the author? (as per "Written, dramatic, musical and artistic work") https://www.gov.uk/copyright/how-long-copyright-lasts You're right. I always thought there was a separate rule for works-for-hire, but I just checked and that's...
by ctr
Thu Jul 12, 2018 8:58 pm
Forum: emulators
Topic: Beebem Mode 7 glitch
Replies: 37
Views: 1484

Re: Beebem Mode 7 glitch

To me this implies double-height backgrounds only get copied down after Double Height 0x8D, and stop getting copied down after Normal Height 0x8C. I read it the other way. "The remaining Character Rectangles" refers to the character rectangles that aren't in double height. So the background is copi...
by ctr
Tue Jun 26, 2018 3:11 pm
Forum: software: other
Topic: BBC Micro Compendium by Jeremy Ruston
Replies: 55
Views: 2035

Re: BBC Micro Compendium by Jeremy Ruston

This might help. Maybe. I used Wolfram-Alpha to calculate the [3/3] pade approximant of (ln(1+x)-x)/x^2 (as used in BASIC2's LN) and then converted it to a continued fraction. This gave the same seven terms as calculating the continued fraction directly. Pade approximants of taylor series and trunc...
by ctr
Mon Jun 25, 2018 2:45 pm
Forum: software: other
Topic: Any short type-ins for unattended Beebs?
Replies: 143
Views: 7263

Re: Any short type-ins for unattended Beebs?

The redoubtable Bruce Clark has posted some type-ins over here: http://forum.6502.org/viewtopic.php?p=60765#p60765 In the third program edit line 60 to change the plus to a minus: - 60 PRINT CHR$(32+3*(C-INT(C)<.4)); + 60 PRINT CHR$(32-3*(C-INT(C)<.4)); I guess Apple BASIC uses +1 for TRUE. In the ...
by ctr
Mon Jun 25, 2018 2:39 pm
Forum: software: other
Topic: BBC Micro Compendium by Jeremy Ruston
Replies: 55
Views: 2035

Re: BBC Micro Compendium by Jeremy Ruston

I don't know if this is helpful, but somewhat to my amazement I've been able to find the original BBC BASIC program It is, but I now realise I got the wrong end of the stick. This is useful for the polynomial approximations, but not the continued fraction ones. I checked that the continued fraction...
by ctr
Fri Jun 22, 2018 10:54 pm
Forum: software: other
Topic: BBC Micro Compendium by Jeremy Ruston
Replies: 55
Views: 2035

Re: BBC Micro Compendium by Jeremy Ruston

C99 and C++17 both support hexadecimal floating point constants so it should be possible to exactly represent the beeb's 40-bit constants. Somehow I'd got the idea that early BBC Basic versions used the ratio of two polynomials, but that seems not to be the case. You were right. The beeb uses contin...
by ctr
Sun Jun 17, 2018 9:58 pm
Forum: stardot.org.uk
Topic: Post editing
Replies: 59
Views: 1386

Re: Post editing

Unless there's some other code you're not posting which makes the css rule domain specific, adding things like that seem like a very bad idea to me. I would recommend using an element blocker like ublock origin for things like that. I like living dangerously! But it's a fair point. Here's a ublock ...
by ctr
Sun Jun 17, 2018 8:23 pm
Forum: stardot.org.uk
Topic: Post editing
Replies: 59
Views: 1386

Re: Post editing

danielj wrote:
Sun Jun 17, 2018 6:32 pm
can the same be done in Chrome?
I don't use Chrome but a quick Google search suggests they removed the built-in feature. Apparently you can get add-ons for Chrome that let you do this.
by ctr
Sun Jun 17, 2018 6:26 pm
Forum: stardot.org.uk
Topic: Post editing
Replies: 59
Views: 1386

Re: Post editing

Edit: there's a safer method below. You can hide these messages locally by adding .notice {display:none} to your browser's user-defined css. In Firefox this is in the file: C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\chrome\userContent.css You could use greasemonkey to do some...
by ctr
Wed May 30, 2018 11:41 pm
Forum: software: other
Topic: Code Query with OSWORD Call
Replies: 4
Views: 290

Re: Code Query with OSWORD Call

Yes, that's right. I find it helpful to remember that the value at the top of the stack is always at &101+S (ignoring when S=&FF). I guess the original return address is still sitting there at &10B/C+X, and would need to be removed at some stage. At the start of .code2 it gets overwritten by the new...
by ctr
Wed May 30, 2018 8:13 pm
Forum: software: other
Topic: Code Query with OSWORD Call
Replies: 4
Views: 290

Re: Code Query with OSWORD Call

.code1 LDX #&07 .loop1 LDA &00A8,X ; Copy 8 values from &AF-&A8 to the stack. PHA DEX BPL loop1 PHA ; Create space on the stack PHA ; for a return address. TSX LDA &010B,X ; Copy the original return address STA &0101,X ; into the space just created. LDA &010C,X STA &0102,X RTS ; Return to the calle...
by ctr
Tue May 29, 2018 5:13 pm
Forum: emulators
Topic: Emulator setup to make all ROM area writes use bank 15 SWR
Replies: 23
Views: 629

Re: Emulator setup to make all ROM area writes use bank 15 SWR

I used a similar build system for my sideways ROM projects bitd. I had a Watford board, which works as you describe.

They build fine using beebem and the code ends up in RAM bank 4.
by ctr
Sun May 27, 2018 10:01 am
Forum: stardot.org.uk
Topic: Image sizes
Replies: 59
Views: 1114

Re: Image sizes

I can't see the image either, whether logged in or out. If I use wget I get a straight 404 not found. Is it expecting a cookie to say you've accepted cookies? I've somehow avoided accepting the cookie permission thing. Edit: This is unlikely to be the problem. Other images work OK. It's just this one.
by ctr
Sat May 26, 2018 10:02 pm
Forum: stardot.org.uk
Topic: Image sizes
Replies: 59
Views: 1114

Re: Image sizes

Whilst I'm on the subject of images - we allow linking to images in signatures - this breaks the ssl thing a bit, as external images might not be over secure links. I can turn this off, but it'd mean no images in sigs... Thoughts on that? Inline images have the same issue. This page shows an exclam...
by ctr
Sat May 26, 2018 9:46 am
Forum: off-topic
Topic: Forum GDPR compliance?
Replies: 58
Views: 1173

Re: Forum GDPR compliance?

* Information (including any program content) posted on a forum is considered to be in the public domain, GDPR does not superceded a persons responsibility to protect their own information, or be accountable for what they disclose in public. In such cases existing laws still apply. I think it's wor...
by ctr
Sun May 13, 2018 10:02 pm
Forum: software: new games
Topic: New version of Scramble for the beeb (going well)
Replies: 140
Views: 7936

Re: New version of Scramble for the beeb (just starting)

Comparing it to frogger you've changed the horizontal sync width from 8 to 9 (R3 from &28 to &29). Is that a typo?
by ctr
Sun May 13, 2018 11:17 am
Forum: development tools
Topic: BeebAsm
Replies: 73
Views: 5803

Re: BeebAsm

No, thank you! That's brilliant. I've committed a new Windows exe. We might as well carry on in proposed-updates, it's easier to type and you've tagged the release if anyone wants to go back to that particular version. Though I committed the exe to master so that would have to be merged back in to p...
by ctr
Tue Apr 17, 2018 11:35 pm
Forum: software: other
Topic: How t pass arrays into procedures?
Replies: 14
Views: 998

Re: How t pass arrays into procedures?

On a real beeb keywords like COLOUR and PRINT are tokenised to a single byte when you enter a line of code, so abbreviating them doesn't make any difference to the memory used.
by ctr
Mon Apr 09, 2018 8:19 pm
Forum: software: other
Topic: Any short type-ins for unattended Beebs?
Replies: 143
Views: 7263

Re: Any short type-ins for unattended Beebs?

You could possibly shorten this by using a four-element array for the positions and a similar array for the velocities. 0REM Walking Lines 10MODE2 20VDU23,1,0;0;0;0; 30X%=640:Y%=512:A%=768:B%=768 40V%=32:W%=24:C%=16:D%=-28 50DIME%(7),F%(7),G%(7),H%(7) 60FORI%=1TO7 70GCOL3,I% 80MOVEE%(I%),F%(I%):DRAW...
by ctr
Fri Mar 30, 2018 12:55 am
Forum: software: new games
Topic: Prince of Persia
Replies: 119
Views: 6845

Re: Prince of Persia

Bravo!

This is brilliant. The graphics look incredible, the animation is absolutely rock solid and the sound works really well. And it's a good game!
by ctr
Sun Mar 25, 2018 8:04 pm
Forum: development tools
Topic: BeebAsm
Replies: 73
Views: 5803

Re: BeebAsm

Prime wrote:Also what is the currently worked upon branch of the source as I'd like to test the updates.....
https://github.com/stardot/beebasm/tree ... ed-updates

Note that the EXE isn't quite up-to-date. It does include all the new features.
by ctr
Sun Mar 25, 2018 4:31 pm
Forum: off-topic
Topic: Acorn Art Thread
Replies: 450
Views: 32420

Re: Acorn Art Thread

I'm loving these animations.

Having already written some code to convert the original pictures into MODE 2 format I extended it to handle the animations. A couple of ssds are attached.