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I've released version 1.11a of BBC BASIC for SDL 2.0 - the cross-platform programming language for Windows, MacOS, Linux, Raspbian, Android and iOS. For anybody who may be struggling to install it on MacOS 10.15 'Catalina' , and being faced with apparently insuperable security warnings, the require...

Changed the default MODE 7 font to be more similar to RISC OS and Matrix Brandy. This is the font I am now using for MODE7. It's loosely based on the Bedstead-ext font but, since that is a 12x20 bitmap stretched (with anti-aliasing) to 16x20, 'smooth' diagonals run at a different angle; this partic...

I've released version 1.11a of BBC BASIC for SDL 2.0 - the cross-platform programming language for Windows, MacOS, Linux, Raspbian, Android and iOS. The changes in this version are as follows: BASIC Interpreter / Run Time Engine Enabled render batching (in SDL 2.0.10 and later) which should improve ...

well i havnt found out exactly why, but if i do a proc with in a proc, sometimes i wont work the pins properly. I'm not exactly sure why it isn't always working, but I'm worried about all those global variables (A, B, C, D, E, F, G) which is not a very good way of doing things (excessive use of glo...

The FontManager modules can do this, it's completely separate from the BBC-style text plotting. I see, I'm entirely unfamiliar with that. Is there anything comparable available when using Matrix Brandy on Windows (or Linux for that matter)? Could I use the SYS statement to access an API function th...

Currently, it's tied to MODE 7 due to the way the code is written. In all other modes, a character is assumed to be 8x8 OK, understood. In ARM BASIC running on RISC OS there must surely be a way of achieving higher-quality VDU 5 text in a graphics mode, for example if one was trying to write a GUI ...

This is possibly a silly question, but can the MODE 7 font be used in any other mode? My thinking is that because it's not tied to hardware, as it was in the BBC Micro, but is just another bitmapped font (albeit, at 16x20, a higher resolution than most) it ought to be possible to use it in any MODE ...

One problem however is that some LCD TVs require the SCART control signals on pins 8 and 16 to be correct. Absolutely. It's not just that the TV may need it, the SCART specification mandates it! A conformant RGB to SCART lead needs to be able to apply a suitable switching voltage to pin 16, and if ...

Wikipedia suggests it was first implemented in 1977, and required on French TVs from 1980. I have no reason to doubt that, but I don't think it was common on TVs in the UK until much later; I don't remember it being on Acorn's (or the BBC's) radar when the BBC Micro was being designed (1981). But t...

The biggest problem with SCART leads, is not the Beeb, or the SCART lead, but that this is a standard that was developed long after the Beeb was designed. Yes and no. SCART was of course developed long after the Beeb, but the signals it carries mostly correspond to TV standards established decades ...

I have today released version 6.13a of BBC BASIC for Windows . This is a maintenance release, primarily to fix the recently reported (but apparently known about for quite some time) bug in the WIDTH() function. The changes in this version are as follows: Interpreter / Run-Time Engine : A fairly seri...

Mono picture from Composite is good. Degrades considerably when the capacitor is soldered in place... Yes, and the composite PAL quality - if you can make it work - will be even worse. I would suggest abandoning that approach and concentrating on getting the SCART connection working. Have you tried...

Would that cause more problems than it solved? I'm not sure that there is actually a 'problem' that needs solving. Since the 920-character limit was specific to Prestel, and not a guarantee made by the Viewdata specification, no terminal (whether ancient or modern) should be relying on it. Even wit...

My understanding is that 7-bit escaping is part of the transmission protocol that’s necessary due to modems of the era, rather than something intrinsic to the characters or control codes themselves. Yes, but the point is that (as I understand it) Prestel had a 920 character limit including the cont...

Sorry, no. I don't have a Mac I found that buying a Mac was unavoidable, in order to build BBC BASIC for SDL 2.0 for Mac OS (I also use it to build the iOS edition). But it wasn't too expensive because I got a Mac Mini and share my keyboard/mouse/monitor using a KVM switch. I also find the Mac to b...

I guess it's a point to consider when designing a Viewdata gateway Hacking my telstar.bbc terminal to count the number of received characters, the Engineering Test Page (page 793 on Teefax) totals 1367, which is nearly 50% more than the 920 'limit'! So when I see a character 12 (0C) go by, I start ...

Spectacular! On re-rereading the thread, I see the accuracy increases threefold on each iteration - I'd mistakenly said it doubles. In fact, AIUI, it's the number of significant figures (or bits) which triples at each iteration, which is a vastly faster convergence than what I originally understood...

Here's a simple, fast, and accurate one: That's neat, and what is astonishing is that after only 5 iterations not only is it accurate to the 9 significant figures of 6502 BBC BASIC, but it's also accurate to the 19 significant figures of BBC BASIC for Windows and BBC BASIC for SDL (when running on ...

I made a slight error, the max page size was 920 bytes including esc chars etc. Since this was a Prestel-specific limitation (rather than something imposed by the Videotex specification or transmission protocol) it would have been unwise for a terminal manufacturer to rely on it, because it wouldn'...

when i run the BBC basic on the pi, say i press the delete key for 1 second it keep on going for ages, there is a lag, is there a way to sort that ? Sorry about that, it's because the auto-key-repeat is filling the keyboard buffer faster than the program editor is able to process those delete comma...

yes sorry! 50 Hz is probably within the range you could achieve in 'pure software' with care (certainly if you are prepared to use assembly language), but I'm unsure about the PWM aspect. Stepper motors I've encountered (and that's years ago) didn't use PWM, they were fed with two signals in quadra...

avtovaz wrote: ↑

Sat Mar 14, 2020 9:12 am

is there any way in bbc basic i can produce pwm around the 50 megahertz so i can control a stepper motor? thanks

You don't really mean 50 MHz, surely? In the context of a stepper motor, do you mean 50 Hz?

BeebMaster wrote: ↑

Thu Mar 12, 2020 2:22 pm

Don't think it will make a difference but I notice it's a 1KV rated capacitor.

Won't make the slightest bit of difference at video frequencies (< 6 MHz).

I've coded the algorithms that we know about in the program below (it runs in BBC BASIC for Windows , BBC BASIC for SDL 2.0 or Matrix Brandy ). If somebody can add a section that reproduces ARM BASIC's results that would be of interest: 10 @% = 9 20 N% = 99 30 40 PRINT "6502 BASIC 2:" TAB(23); 50 se...

Or make the BNC problem go away by replacing the connector on the conputer with a chassis mount RCA socket. (got that t-shirt). Hmm, as a (once) professional video engineer I can't say I like the idea of replacing a high-quality constant-impedance BNC connector with a cheap phono connector, however...

No idea what Z80 or ARM might be doing though! I can find out what the Z80 version is doing, if need be! Edit: actually 6502 BASIC is scaling up the results of RND(1), which is a kind of "cooked" version of RND. So even when RND is returning an integer it is internally using floating point operatio...

An alternative strategy, if you were trying to avoid the cost of a modulus, might be to mask out excess bits (AND 127 in this case), and then try again with the next value in the sequence if it were out of range. I don't think that would have been considered an acceptable approach, because of the t...

Sorry to resurrect this thread after nearly a year, but I've recently had reason to revisit this subject. Having noted that all versions of BBC BASIC produce the same results from: PRINT ~ RND(-1) RND RND RND RND RND RND but mostly different results from: PRINT RND(-1) RND(99) RND(99) RND(99) RND(99...

daveejhitchins wrote: ↑

Wed Mar 04, 2020 5:52 pm

That shouldn't be a big issue a you can park in the nearby retail park and walk over!

I don't remember it being that close. Is there a pedestrian shortcut from the retail park to the museum?

LordVaderUK wrote: ↑

Tue Mar 03, 2020 5:14 pm

Thanks - have emailed them to check I won’t be engulfed by swarms of schoolchildren!

Also a good idea because parking there is very limited.