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You could change every colour in that game to black, and it'd be no less playable.

Cracked it!! Properly this time!

Very inventive and original Definitely very satisfying when you figure out the trick

Bravo Lurkio!

My doubts were valid as Lurkio confirmed that I found a loophole rather than solving it in the intended way.

So back to square one Time to do it properly!

Looks absolutely beautiful guys, huge congratulations for getting it finished! Have barely had a chance to try it, but it really looks smooth and colourful, and I don't notice any graphical blockiness when playing at all (assuming that you had to double up pixels in the end to make it all fit?). I'm...

I also solved it! \:D/ Not exactly sure if I did it 'right' as my method was a bit hit or miss. The hints were helpful, yes, although I'm not quite sure what they were trying to tell me towards the end. An intriguing little puzzle - and it's worth mentioning that not all the commands it recognises a...

It would probably INCLUDE/INCBIN from the wrong place though. I originally planned on making them relative to the file being assembled, but it was a bit of a pain to do and I never got round to it. It'd need to maintain the base directory (everything up to the final slash) and pass that to subsequen...

That needn't be a BeebAsm feature - you could just do something like: mkdir beeb mkdir elk mkdir master beebasm somecode.asm -DMACHINE=0 && move output.ssd beeb beebasm somecode.asm -DMACHINE=1 && move output.ssd elk beebasm somecode.asm -DMACHINE=2 && move output.ssd master ...

Isn't this what the 6502 RDY pin is for? Pull RDY to halt the 6502 and free the data bus (only works on CMOS 6502s as far as I know, as NMOS ones can't be stopped for very long).

How long does it leave between flipping the write enable line to the sound chip? You're supposed to leave 8uS but I think you can get away with less on a real Beeb... Only if you're lucky. I think the point is that the sound chip only takes data off the bus every 8us, so if you get lucky it'll work...

No one really knows. No one seems to know for sure who the current copyright holder is after Acorn rights were split between Pace, Broadcom, Castle, RISCOS Ltd and whoever else. I remember back around '96-'97 someone (from Acorn I guess) popping up on the old BBC Micro Emul8 mailing list granting un...

Having a quick look at the OS 1.20 disassembly, it doesn't look as if any special handling is given to OSBYTE &81,&00,&FF - it seems to actually drop through to the keyboard scan code and presumably always guarantees a consistent return value. In later OSes I guess they had to hardcode s...

It'd never occurred to me that the INKEY-256 thing was originally undocumented. It is very obscure - piggybacking off a totally unrelated API for no apparent reason. Not even sure why they couldn't just use OSBYTE 0 to return this information - having two separate calls with slightly different retur...

Try adding 128 to the ASCII code if you're writing it out with VDU or PRINT. If you're writing directly to the screen, 127 or 255 will work equally.

(As guesser just said )

To be perfectly honest I haven't the faintest idea what he's on about. Bin Doon? Human Rights Movement? Nothing ever seems to get deleted? Our right to freedom of association? What?

This page documents the HxCFloppyDiskEmulator, and this mentions a maximum transfer rate of 500kbits/sec for MFM - so I think the file format is just reflecting that (after all, the file format is designed for the emulator, right?). However they also mention a rotation of speed of 600rpm instead of...

500 kbits/sec is just the normal double density MFM bitrate isn't it? Does seem totally arbitrary as it would presumably even exclude quad density and beyond.

I think I agree with the criticisms above that FDI really should have decided what sort of file format it wanted to be and done that well, rather than including both the high-level and the medium/low-level tracks. One's instinct when reading the FDI spec isn't that it would be fun to implement, it'...

Not sure if it's been mentioned already, but just throwing something else into the mix. The Software Preservation Society have the IPF (Interchangeable Preservation Format) file format, which they seem to be pushing as the standard for archiving disk images for any platform. However, for IP/patent r...

Just to add, another good reason for a chunked format (with simplified chunks for regular data if it's easy to implement) is that this then also permits for more esoteric data to be represented, such as the infamous weak/fuzzy bits. A straight bit image is more inflexible, in exactly the same way th...

Depends whether human readability on inspection is deemed an important property I guess. I quite enjoy* opening up .uef files and looking for messages and so on, because one of the chunk types in a uef is simple 8 bit data with implied start/stop bits, and that's the preferred format for any tape im...

Bits represent flux transitions not absolute levels so, pedantically, doubling up on bits wouldn't be correct but spacing them out would be. Yeah, good point. Assuming a 1 represents a transition, I guess it'd have to be interleaved with 0s. Not a great way to represent the data, but at least it's ...

Is a compiled windows version avalable anywhere I. E. Exe file to download? Peter. No - it's easy enough to compile in Visual Studio if you want, but really it's more of a reference implementation than anything with a concrete use, given that nothing currently supports the files it outputs! The mai...

What I was meaning regarding storage of the data was... I could trivially store "FSD" as binary, representing each 0 and 1 in their numerical form, taking one byte per number resulting in the following in a file "01000110 01010011 01000100" and then converting when loading. I'd ...

Here is the tool I wrote to convert FSD to FDI medium-level images. Unfortunately they're not yet supported by any BBC emulator...

Here is the specification for the FDI file format. It supports three different levels of accuracy, each with different size requirements. The .fdi images that were on the old Acorn Preservation site were low-level images which essentially sample the magnetic data on the track and can encode weak/fu...

I've stated my view on this before, but will repeat it again - I personally dislike establishing yet another file format for disk images when there is an existing one (fdi) which is able to represent a disk image in the same medium-level form as fsd, with much the same file size. I wrote a small uti...

You could just add as your first line



Will delay the program a bit on an emulator which keeps Shift held for a long time, but at least it fixes the issue!

Yeah I don't think there's a way to discriminate odd and even fields on a Beeb (funnily enough, it *is* possible in B-Em and jsbeeb, because they set CA1 high half a scanline too soon on odd fields - little bug there). The only way you could do it is if you could see the HSync signal, and then time ...

I may be wrong, but I didn't think the CPC464 had something like shadow screen memory. It just uses CRTC R12/R13 like we do in Beeb land. Whether it can address more than 32k of RAM is a different question I guess. Certainly 32k screens (as are occasionally used on the CPC) are already a hardware im...

remember to set the sound volume to silent... Thanks tricky. Presumably this is the volume for tone generator 1 rather than the noise channel? It should be fairly easy for me to try this out so I'll give it a go in the next day or so. (I've just started looking at a CPC emulator so that's taking up...