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Hi. The line that actually plots the point is line 970. This line performs an EOR which is why the second run removes the circles. Change it to ORA to stop this. Mode 5 does indeed produce a rather psychedelic pattern. However, be warned that the code assumes mode 4 and does not yet filter off-scree...

My original code (see "Drawing a circle in BBC Basic") took 7.86s to complete. However there was a small bug that prevented the last circle from being drawn. Changing line 210 fixes the problem: 210 SEC:LDA #&F8:SBC RL:LDA #&01:SBC RH:BPL radloop It now takes 8.42s to complete. Rem...

Hi. With all this talk of Floppy Disk Controllers and Disk Archiving etc, I thought I'd add that for the past 6 weeks I've been working on a solid state floppy disk drive (SSFDD) to attach to the Disk Port (thus freeing up the User Port). Unfortunately, I've been working full time during lockdown et...

I learned Pascal whilst doing A Level Computer Science, and I have a copy of S-Pascal (boxed, with manual)! Before producing the Assembler version of the Bresenham circle drawing program, I created it in Pascal assuming it would run faster than BASIC. I was wrong, but I suspect this is to do with al...

Are you sucking or blowing? Mark Erm, well both - sucking from the main PCB and blowing into the PSU. Air flows out under the Beeb via the vent under the PSU. I figured that this was best as the PSU generates the greatest amount of heat, so it was best to get ride of it quickly rather than blow it ...

I bought a 40mm (40x40x10) "Silent" fan and some Raspberry Pi type Heatsinks. I cut a 38mm diameter hole centred 50mm from the left and 25mm down for the fan. This allows airflow in the main part of the PSU and some to the left and a little above. I added a 12v pair from the PSU for the fa...

Yeah, 209.6 minutes (3.5 hours).

Can't wait for the video.

Sure, but the PCB moves back about 15mm so there might just be a suitable connector - it needs it be short and fit the holes on the PCB. It's probably much simpler to just add a simple connector in the two wires. Close, but no cigar: https://www.alibaba.com/product-detail/Jack-R-A-PCB-mount-mini_141...

Hi. On my BBC B it looks very much like a right angled BNC connector was intended for the Video Out socket (there are markings and holes in the PCB). This would be in preferance to having to desolder the short leads to remove the PCB. I've been searching for a suitable connector but can't find one. ...

Hi.

I don't think the code is correct.

A time of 366100 is 1h 1m 1s, but the code states 1h 1m 61s

I believe this gives the h, m, s (I've changed R to T):

walkerworks wrote: ↑

Sat May 09, 2020 10:56 am

I thought I'd try it on my Elk/plus1 with e2p and it took 3m 5sec to complete.

Nice!
How long does the first posted version take?

I was asked about the Eight Queens Puzzle in the early 1990's - 1992 I think. Version 1 of the program back then took over an hour to run on an Elk. If nothing else, this has been an example of how detailed knowledge of hardware and software allows small changes to have big impacts. It's probably po...

Can we submit a fix request or do you think it's a bit late now?

Thanks again. On my BBC B, the last version I posted takes 7m 33s. Disabling the solutions output (but keeping the progress indicator) it takes 7m 13s. Disabling all output it takes 6m 59s. The output is taking about 7.5% of the time. I'll look into maximizing performance. Pi4 rejected G%() ? Intere...

I think there's a little room for further improvement. https://bbc.godbolt.org/?embedBasic=10%20REM%20EIGHT%20QUEENS%20PUZZLE%0A20%0A30%20MODE1%3A%20REM%20SORRY%20ELK%20OWNERS%0A40%0A50%20DIM%20G%25%288%29%0A60%20S%25%3D0%0A70%20PX%25%3D0%3APY%25%3D0%0A80%0A90%20PROCCHOOSE_QUEEN%0A100%20PROCCHOOSE_B...

It's good to know that 3 decades in IT didn't go to waste: 10 REM Eight Queens Puzzle 20 30 MODE1: REM Sorry Elk owners 40 50 DIM G%(8) 60 S%=0 70 PX%=0:PY%=0 80 90 VDU23,1,0;0;0;0; 100 VDU23,224,24,60,24,24,24,60,60,126: REM elkrepair 110 VDU23,225,0,36,129,60,126,126,60,126: REM elkrepair 120 VDU2...

Thanks sydney! That's quite good.

My efforts weren't great:
I've added the UDG and colour, and Iooking at the code after at least 25 years I think I can speed it up a little. I'll post an update later.

My Beeb does it in 9mins 42secs. My electricity must be faster than yours!

Thanks. I think there are only 12 distinct solutions. All the other solutions are reflections or rotations of the 12. The search level is the row number currently being searched, so a solution will only be found whilst on level 8 (hence the pop-up asterisk). I can re-write the code to be more readab...

Hi. How about the Eight Queens Puzzle: https://en.wikipedia.org/wiki/Eight_queens_puzzle I produced this code many many moons ago, so appologies if it's a bit rubbish. It takes just under 10 minutes to run on my BBC B, although it does produce output as it runs. It uses recursion. 10 REM Eight Queen...

Hi.

I've been looking for a document describing the Disc Drive interface protocol but can't find one. Does anyone know of where I can obtain one?

I'm interested in exactly what goes in and out of the Disc Drive port.

Many thanks.

What does one use to open a dsd file?

The Beeb hadn't been on for 24 hrs, so before switchng on I measured the internal temperature and it was 19C. Room temp was 19C, rising to 20C. After 2 hours of mindless circle drawing and endlessly spinning a Cobra MkIII, the internal temp was 38C, the PSU 45C, the 6502 & Video Processor 55C. I...

Hi. I have a Beeb B with replaced caps in the PSU. I'm a little surprised how hot the PSU and other components can get, so I was invesigating how to cool things down a little without significantly compromising the look & feel (internal and external). I figured I could put some small Raspberry Pi...

Thanks! I never knew about the OPT being on the same line as the [ but now I do. Everyday is a learning day. The code isn't quite fully XOR compatible - the first and last points can cause parts to go missing when XORing. However, the modified BASIC code below does support XOR: 10 REM BRESENHAM CIRC...

Well, despite not writing any 6502 assembly for 35 years, I've managed to do it. I've deliberately kept it simple - introducing efficiencies could reduce the execution time a little. 10MODE4 20 30RL=&70:RH=&71: REM Radius 40XL=&72:XH=&73: REM Pixel X coord 50YL=&74:YH=&75: RE...

From "RLOAD is small program which can be used to load sideways ROM images into any chosen socket" i inferred that TuroMMC would manage a kind of 'virtual ROM' or something. I now realise that the chosen socket needs to contain Sideways RAM. Time to get the wallet out again! Which ROM is t...

Ah. Sideways RAM. Yeah, I can see how that might help.

I assumed the loaded ROM was 'managed' by TurboMMC somehow.

No, no sideways RAM.

Slots 11 to 15 are used by OS, 1770 DFS, TurboSPI, Basic, Graphics ROM.

If I do:
*DIN305
*RLOAD ADT200 A
*ROMS

Then ROM 10 will show either BASIC or DFS 0.A3

Weird.

Hmmmm.

I've used *RLOAD to load ADT but it just loads DFS 0.A3 into the ROM slot. I tried DDOC as well and the same happens.

I was looking for a tool to try recover files from a disc.

Please excuse my ignorance, but what am I doing wrong?