Search found 2616 matches

Mon Oct 14, 2019 4:56 pm
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

Sorry, my simple-minded changes to use peek and poke instead of arrays seems to be broken code - possibly because of operator precedence.
Mon Oct 14, 2019 11:43 am
Forum: programming
Topic: What is (zp,X) actually useful for?
Replies: 10
Views: 351

Re: What is (zp,X) actually useful for?

(With the data stack base pointer in ZP, you'd be using X as the stack pointer. It would most likely be a data stack, not a code stack for return values - that's still in page 1. Although, there might be interpreter designs where you manage your own return stack. In any case, it's at most a 256 byte...
Mon Oct 14, 2019 11:14 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

(That said, we can improve the GOTO by executing it much less often: put in a NEXT first, and then direct the GOTO to the line after the NEXT.) (Hmm, I see JGH's two GOTOs have different targets, unlike Valentin's original... and I see that's to do with the deferred printing. But this code may have ...
Mon Oct 14, 2019 11:09 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

My feeling - dangerous, should measure it really - is that almost all the work is in the inner loop, and if that's true, there are only minor gains to be made elsewhere. Of course in part this depends on how many digits you want to compute. 130 FORI%=L%TO1STEP-1 140 K%=K%-2:X%=10*A%?I%+Q%*I% 150 Q%=...
Mon Oct 14, 2019 10:21 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

BTW, my switch to indirection rather than array mightn't have helped at all, as I wasn't necessarily timing like-for-like. (Edit: it also seems to produce wrong results!) There's a small win from merging lines in the inner loop, and a small win from converting one, other, or both of the small consta...
Mon Oct 14, 2019 10:18 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

Yes, paste from clipboard was a big help. But I made the tactical error of pasting the Sharp Basic original and then fixing it up within JSBeeb, instead of working on a master copy and re-importing it. So the other half of the function, copy-from-printer, would be very handy. Copy-from-screen might ...
Mon Oct 14, 2019 8:30 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

Perhaps *SPOOL to the copy/paste buffer, or into a little text area from which one could copy and paste? If not *SPOOL, then capture the RS432 output... for which we need to know some *FX trickery. But wait: the OS supports a printer, and control-B enables it, so how about capturing that output into...
Mon Oct 14, 2019 8:27 am
Forum: programming
Topic: What is (zp,X) actually useful for?
Replies: 10
Views: 351

Re: What is (zp,X) actually useful for?

By complete coincidence, Garth Wilson over on the 6502.org forum has just volunteered this : Many users have wondered why the (zp,X) was even there, thinking it was a waste because it never gets used. Well, it does get used, constantly, in languages that use a data stack in ZP (which is separate fro...
Sun Oct 13, 2019 2:51 pm
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

There's a thing you can do, to calculate in base 100 or even base 10000, which is more efficient. Here's some BCPL as a hint, by revadlinho:
https://github.com/revaldinho/opc/blob/ ... got-bcpl.b
Sun Oct 13, 2019 12:31 pm
Forum: programming
Topic: What is (zp,X) actually useful for?
Replies: 10
Views: 351

Re: What is (zp,X) actually useful for?

I sometimes think of (zp),Y as a pointer to struct (or pointer to array) and (zp,X) as an array of pointers (But it would have to be a small array, as it's in zero page.) I see three or four uses in the BBC OS and Basic, squinting at a quick and dirty disassembly, and in all cases (zp,X) is used whe...
Sun Oct 13, 2019 11:29 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

Edit: this code appears to be bogus! Do not use! We can go a little faster if we use peeks instead of array accesses. 50 digits in 50 seconds. 10INPUT"How many digits",N% 20T%=TIME 30L%=10*N%/3+1:DIM A% L% 40Z\$="000000":T\$="999999" 50FORI=1 TO L%:A%?I=2:NEXT 60M%=0:P%=0 70FOR J%=1 TO N%:Q%=0:K%=2*L%...
Sun Oct 13, 2019 11:20 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

Excellent, thanks!
Sun Oct 13, 2019 10:48 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

I'd like to, but I'd need to type it in... that's a drawback of experimenting in JSBeeb.
Sun Oct 13, 2019 9:53 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Re: Calculating digits of Pi in Basic

And indeed, an integer version computes 50 digits in 54 seconds:
Sun Oct 13, 2019 9:41 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 33
Views: 434

Calculating digits of Pi in Basic

Valentin Albillo, ingenious programmer of HP and Sharp calculators, offers a Pi-calculating program in just 7 lines of Basic, in this PDF as seen on his web site (where there are many other interesting works). Here's his program, for a Sharp pocket computer: 1: “A” CLEAR: INPUT N: L=INT(10*N/3): DIM...
Fri Oct 11, 2019 4:41 pm
Forum: emulators
Topic: Anyone bought or seen the Pi emulator sold on ebay?
Replies: 3
Views: 130

Re: Anyone bought or seen the Pi emulator sold on ebay?

Well, if it's nicely packaged and properly licensed I don't object.

I'd like to see a slick boot-to-Beeb package for the Pi - especially if it worked with a Pi 1 or a Pi Zero, and if it had the most accurate smooth tear-free and frame-skip-free emulation.
Fri Oct 11, 2019 4:26 pm
Forum: emulators
Topic: Anyone bought or seen the Pi emulator sold on ebay?
Replies: 3
Views: 130

Anyone bought or seen the Pi emulator sold on ebay?

I'd be interested to know what the inside story is on the \$9 emulator package being sold on ebay for the Pi. Has anyone bought it or seen it? I'm guessing it's a boot-to-MAME configuration. I wonder if it runs smoothly on any Pi - I see now it says it's for Pi 2 or Pi 3. https://www.ebay.com/itm/Aco...
Fri Oct 11, 2019 4:19 pm
Forum: stardot.org.uk
Topic: PM system, when is it activated for new users?
Replies: 21
Views: 968

Re: PM system, when is it activated for new users?

I hope you'll see, @wiss, that this is a friendly place. Lots of help, lots of sharing. Just join in, show us you're a friendly person by being a friendly person. Tell us about the other community too - that's OK.
Tue Oct 08, 2019 6:11 pm
Forum: acorn atom and system
Topic: Acorn Atom on the Blackice Mx ice40 FPGA
Replies: 2
Views: 93

Re: Acorn Atom on the Blackice Mx ice40 FPGA

Welcome, lawrie! (For background: the Lattice FPGAs used on the BlackIce boards can be programmed using open-source tools, which is an attractive option for many people, including me. And the tools are not so ridiculously large a download as the commercial tools. There's a discussion board for all t...
Sun Oct 06, 2019 5:30 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2060

Re: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list

Could we have a list of a few no-kitters? I see lawrie from the mystorm forum is interested. And Revaldinho could join as a no-kitter if a table space didn't open up.

I've got a couple of pasting tables I can bring.
Wed Oct 02, 2019 3:11 pm
Forum: general
Topic: Remarkable videos recently posted on Youtube
Replies: 276
Views: 31645

Re: Remarkable videos recently posted on Youtube

Two of the talks from the recent Acorn World at CCH are up: Jonathan Griffiths - Acorn World Talk Jonathan Griffiths talks about his time at Acornsoft, where he wrote some of the first arcade games for the BBC Micro as well as contributing to the BBC Domesday Project. Jonathan spent his A-levels tea...
Mon Sep 30, 2019 6:31 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2060

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

Won't do any harm!
Mon Sep 30, 2019 5:49 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2060

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

But this will be a working Vectrex!! (I can always bring mine again if anyone fancies a bit of mixed-signal debugging with some HT nearby. I reckon the digital section is fine, so something's wrong with the tube, or the HT, or the analogue output stuff.)
Mon Sep 30, 2019 7:58 am
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2060

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

Count me in for three days please!
Mon Sep 16, 2019 2:15 pm
Forum: other vintage computer hardware, software and games
Topic: The 8-Bit Guy's new 65816 based computer
Replies: 54
Views: 2763

Re: The 8-Bit Guy's new 65816 based computer

It's a fundamental thing, that the ridiculously low cost of electronics today is all down to scale. If you take away the scale - which almost all retro projects do - you're left with a very different price structure. Even 1000 units is not a volume production run, to the factories which make stuff i...
Mon Sep 16, 2019 2:00 pm
Forum: other vintage computer hardware, software and games
Topic: The 8-Bit Guy's new 65816 based computer
Replies: 54
Views: 2763

Re: The 8-Bit Guy's new 65816 based computer

oops - crossed in post One nice thing about through-hole is that you can sell as a kit. So no assembly costs. But there will be support costs, and returns, from people who really don't know what they are doing. At the other end, once you're all surface mount - which Dave Murray seems to suggest as a...
Mon Sep 16, 2019 11:24 am
Forum: general
Topic: Awesome collection of 70's & 80's tech docs and data sheets
Replies: 21
Views: 521

Re: Awesome collection of 70's & 80's tech docs and data sheets

Serendipity! Who would have expected 100's of articles from the BBC's Engineering Department?
https://archive.org/details/bbc-monographs-80/page/n5
Sun Sep 15, 2019 5:30 pm
Forum: hardware
Topic: CRTC timing with 2MHz clock
Replies: 15
Views: 489

Re: CRTC timing with 2MHz clock

In the case of a '2MHzE even' clock shape, it does look like there's a falling edge on 1MHzE a full cycle before time Q, and yes, I would expect the 6502 and glue logic to have done all the necessary things by this time. (I say that without having studied the schematic.)
Sun Sep 15, 2019 11:08 am
Forum: other vintage computer hardware, software and games
Topic: BCS ITNow ZX81 Issue
Replies: 3
Views: 327

Re: BCS ITNow ZX81 Issue

And again from the BCS website, here's one for beeb-spotting: And a slightly older one for Commodore fans:
Sun Sep 15, 2019 11:04 am
Forum: other vintage computer hardware, software and games
Topic: BCS ITNow ZX81 Issue
Replies: 3
Views: 327

Re: BCS ITNow ZX81 Issue

Hope some of the content is online. Here's something related from the BCS website: