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the ULA reads the byte from memory, and the xyz are the correct bit values from the byte it read, ie, they're actually values intended for other pixels, but if you've programmed the palette 'correctly' for the mode then all possible entries for 1xyz (ie 1000, 1001, 1010, etc) give you the same outp...

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...

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...

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...

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 ...

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...

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 ...

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=...

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...

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...

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...

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...

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 ...

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...

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...

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 ...

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.

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...

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...

.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...

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.

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.

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...

* 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...

Comparing it to frogger you've changed the horizontal sync width from 8 to 9 (R3 from &28 to &29). Is that a typo?

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...

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.

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...

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!

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.