Search found 81 matches

by ctr
Thu Jul 20, 2017 3:37 pm
Forum: software: other
Topic: osbyte call ? and which adress
Replies: 4
Views: 95

Re: osbyte call ? and which adress

I should have looked at the beeb wiki in the first place:

OSBYTE 129 with X=0 and Y=255 reads the OS version.

The original code is saying if this isn't an Electron then partially reset the NETV vector.

OSBYTE 163 checks for various extensions.
by ctr
Thu Jul 20, 2017 12:07 pm
Forum: software: other
Topic: osbyte call ? and which adress
Replies: 4
Views: 95

Re: osbyte call ? and which adress

&FFB7 holds the address of the default vector table. As seen here . !&FFB7 is the address of the default vector table (&D940 on OS 1.20). ?(&24+!&FFB7) is the low byte of the default NETV vector. ?&224 is the low byte of the NETV vector. So you are replacing the low byte of t...
by ctr
Sat Jul 15, 2017 11:40 pm
Forum: software: new games
Topic: New Games Index
Replies: 18
Views: 455

Re: New Games Index

The link to my Tetris game should be tetris.ssd.zip.

The original Stardot thread had an old version in the top post. I've updated it now.
by ctr
Thu Jun 29, 2017 7:59 pm
Forum: emulators
Topic: BeebEm capture video in Windows 8
Replies: 8
Views: 1492

Re: BeebEm capture video in Windows 8

It has recently been fixed. The fix will be in the next release.
by ctr
Wed Jun 28, 2017 12:25 am
Forum: software: other
Topic: Confused about boot file
Replies: 4
Views: 220

Re: Confused about boot file

The break key is function key 10. When you press break the OS puts the (notional) key code for f10 into the keyboard buffer. When a program asks for keyboard input the function key definition is returned one character at a time until it is exhausted. e.g. try typing "*KEY10 HELLO" and pres...
by ctr
Tue Jun 06, 2017 3:24 pm
Forum: hardware
Topic: OS RAM module
Replies: 76
Views: 2380

Re: OS RAM module

In BASIC2 LOMEM and HIMEM are freely assignable.

Code: Select all

>LOMEM=&C000:HIMEM=&E000
>PRINT~LOMEM,~HIMEM
      C000      E000

I don't know if the rest of BASIC would cope with this.
by ctr
Sat Jun 03, 2017 5:48 pm
Forum: programming
Topic: Break/continue in BASIC loops?
Replies: 20
Views: 318

Re: Break/continue in BASIC loops?

If you exit a loop with a GOTO then the loop remains active. The terminator of the next loop will actually jump back to the previous still-active loop. An example might be clearer: 10FORI%=1TO20 20PRINT"I ";I% 30PROCLOOP 40NEXT 50END 60DEFPROCLOOP 70FORJ%=1TO6 80PRINT"J ";J% 90IF...
by ctr
Thu Jun 01, 2017 4:54 pm
Forum: programming
Topic: 6502 BASIC Compiler
Replies: 25
Views: 685

Re: 6502 BASIC Compiler

So if I understand the article correctly the summary is. - compiled code much faster unless float based - Compiler code size much bigger ( ABC has runtime library, riscbasic adds to each program) - restrictions on code, more so with ABC They both support libraries, Like *link on mdfs, but requires ...
by ctr
Thu Jun 01, 2017 2:25 pm
Forum: emulators
Topic: Latest version of BeebEm
Replies: 7
Views: 611

Re: Latest version of BeebEm

4.15 is close to being released.

jgh's VDFS changes were a last-minute addition and there is still some discussion. (I'm mungre there.)

And Mike Wyatt has just pushed Music 5000 emulation.
by ctr
Fri May 26, 2017 1:57 pm
Forum: software: other
Topic: Exiting the current language?
Replies: 13
Views: 481

Re: Exiting the current language?

If you use OSHWM upwards then you're destroying the BASIC program, or word-processed document or whatever it is the user was working on. The data left in zero page is an obituary.

At this point there is no reason not to restart BASIC (or whatever) with a clean slate.
by ctr
Tue May 23, 2017 10:12 pm
Forum: software: other
Topic: Exiting the current language?
Replies: 13
Views: 481

Re: Exiting the current language?

As far as I know there is no way to exit all languages on the BBC B because there is nowhere else to go. (If you start the computer with no language ROM it displays "Language?" and stops. In this situation you can boot from a *RUNnable disk, but that's about it.) This doesn't matter though...
by ctr
Tue May 23, 2017 3:35 pm
Forum: hardware
Topic: Question about MEMC translation tables reprogramming
Replies: 12
Views: 321

Re: Question about MEMC translation tables reprogramming

Yes, access to physical memory requires supervisor mode. The audio memory is out of the way at 1F06000-1F07FFF.
by ctr
Tue May 23, 2017 2:27 pm
Forum: hardware
Topic: Question about MEMC translation tables reprogramming
Replies: 12
Views: 321

Re: Question about MEMC translation tables reprogramming

The only potential speed up from using physical memory I'm aware of, is to avoid checking for screen overruns by allowing code to write past &1FFFFFF into the physical memory range. This is also useful for hardware scrolling, as the screen is always mapped to physical pages 0 upward, and physic...
by ctr
Mon May 22, 2017 4:15 pm
Forum: software
Topic: Hacker needed ... for Zarch ;-)
Replies: 147
Views: 7998

Re: Hacker needed ... for Zarch ;-)

tlsa wrote:That screenshot doesn't look like it has dithering enabled to me. Is it the right one?

If you look over the top of the three rockets the furthest background is clearly dithered. If you load the image into a picture editor and zoom it you can see the foreground dithering too.
by ctr
Sun May 21, 2017 6:09 pm
Forum: general
Topic: 8bs.com
Replies: 10
Views: 611

Re: 8bs.com

cjr8bs commented further down that thread. He said the server was hacked and they intend to fix it.
by ctr
Sun May 21, 2017 12:31 pm
Forum: general
Topic: Today ZAP museum received....
Replies: 40
Views: 1225

Re: Today ZAP museum received....

Phone calls were expensive. If the phone was placed conveniently there was a real danger of it being used.
by ctr
Thu May 18, 2017 3:30 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

Does it look the same with UI filtering on and with it off? (It's supposed to, and it does on my laptop at least.) If the UI filtering option is now redundant, I'll get rid of it... Four snapshots of the basic prompt with the filter dialog and messages window visible. I restarted the emulator befor...
by ctr
Thu May 18, 2017 1:02 am
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

(As for whether there are further problems, I don't think so, but there's no shortage of evidence that I could be mistaken ;) The other SDL functions look to add the -0.5 offset in for you, so they should be fine as they are. But SDL_RenderGeometry just passes your vertex data straight through.) I ...
by ctr
Wed May 17, 2017 2:43 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

Yes, d3d11 has half pixel offsets by default, while d3d9 doesn't. Could explain the differences in various machines. Ah! The obvious explanation didn't occur to me. Maybe I'm the only person using the d3d9 rendering and it's just broken. If this is the case then a fix would be to add the offset in ...
by ctr
Wed May 17, 2017 1:30 am
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

I tried d3d11. The good news is that I get the same results with and without the half pixel offset. The bad news is that it's comically broken on this ancient GPU. I tried the half-pixel text offset in a previous post. It has clear text but fuzzy menus as you'd expect. I'm really puzzled by this off...
by ctr
Tue May 16, 2017 10:31 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

I realised that it wasn't just the text but everything in the GUI that had the offset problem. I turned off the filtering and the text offset and hacked SDL's world transformation to move everything by half a pixel: diff --git a/src/render/direct3d/SDL_render_d3d.c b/src/render/direct3d/SDL_render_d...
by ctr
Tue May 16, 2017 3:14 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

I tried commit 1f8c690 which sets a text rendering offset. The text looks great! It is much better than the linear filter.
by ctr
Tue May 16, 2017 1:13 am
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

I edited my previous comment while you were posting. The "linear" filter is an improvement.
by ctr
Tue May 16, 2017 12:36 am
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

I built it on Windows with cmake 3.8.1. gen_6502.py failed because I've got python3. I replaced all the .iteritems() with .items() and that fixed it. You need to add python2 to the instructions as a prerequisite. I need to read the instructions. Building open source projects with lots of dependencie...
by ctr
Mon May 15, 2017 10:55 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

It's possible that a compiled language which supported coroutines as a native language feature might offer the best way to approach emulator code like this (as essentially what you have is a whole bunch of components running simultaneously), but I'm not aware of such a language (and coroutine libra...
by ctr
Mon May 15, 2017 8:46 pm
Forum: development tools
Topic: Request membership of the Stardot organisation on GitHub here
Replies: 35
Views: 1455

Re: Request membership of the Stardot organisation on GitHub here

Please add mungre on github. Thank you.
by ctr
Mon May 15, 2017 7:09 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

If I shrink the window the beeb text also gets all lumpy. There is no anti-aliasing going on. Please could you go to Tools|Messages, click Copy, and paste the output here? Renderer: direct3d, 736x576 SDL_PIXELFORMAT_ARGB8888 Sound: directsound, 48000Hz 1-channel (4096 byte buffer) Also what sort of ...
by ctr
Mon May 15, 2017 4:17 pm
Forum: emulators
Topic: b2 - new emulator
Replies: 62
Views: 1528

Re: b2 - new emulator

This makes such a realistic - and horrible - disc drive noise I thought something had gone wrong my laptop. Then I remembered I don't have a floppy drive! The timeline and clone features are really nice. I had thought of adding a state recorder to beebem but I needn't bother now. Is it possible to s...
by ctr
Mon May 08, 2017 3:12 pm
Forum: hardware
Topic: Palettemate / enhanced video ULA with 4096 colours
Replies: 352
Views: 11282

Re: Palettemate / enhanced video ULA with 4096 colours

And yes, if you read my post, I do say that there is sync circuitry. This drops the video signal to a lower level for the sync pulses. But it is simply a resistor that connects to a logic gate. There is no circuitry to enforce a set level. The sync circuit simply mixes the sync into the video signa...
by ctr
Mon May 08, 2017 12:19 am
Forum: hardware
Topic: Palettemate / enhanced video ULA with 4096 colours
Replies: 352
Views: 11282

Re: Palettemate / enhanced video ULA with 4096 colours

So my conclusion is, either the machine does not generate a "super black" level (it just uses the black border), or it is all done in the ULA. In composite video the sync pulses are periods of super-black so the beeb must generate them or TVs would lose sync when displaying a black screen...

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