Search found 518 matches

by crj
Sun Feb 18, 2018 3:07 am
Forum: hardware
Topic: Some software to test a Music 500?
Replies: 3
Views: 90

Re: Some software to test a Music 500?

What he said. If you're just wanting to make sure it's working, I really wouldn't bother with the Music 5000 software, though. The first option, the Music 500 one, is way simpler and just as effective. As a slight caution, "Syncron" has some stonking great subsonics in it. Be careful with ...
by crj
Sun Feb 18, 2018 3:02 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 311

Re: Music 5000 - sound generation

Careful. As well as the stuff that runs under interrupt (which I believe would be pitch and amplitude envelopes, plus gating, pitch, velocity, tempo and instrument changes taken from a priority queue) there is a co-operative threading system running as the current language. I believe it is mainly th...
by crj
Sun Feb 18, 2018 2:47 am
Forum: off-topic
Topic: Thermionic Valves
Replies: 2
Views: 74

Re: Thermionic Valves

Impressive, but what on earth were they thinking when the chose the shape of the enclosure for some of those? I'm looking especially at the UU5.

Does making it a bizarre shape serve any electronic purpose?
by crj
Sat Feb 17, 2018 3:13 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 311

Re: Music 5000 - sound generation

I guess I could rig up some kind of benchmarking and find out, but does anybody happen to know offhand what percentage of CPU time is burned by servicing interrupts for the Music 5000? (It actually used a User VIA timer, didn't it? I don't believe the Music 5000 itself can actually generate interrup...
by crj
Sat Feb 17, 2018 3:09 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 311

Re: Music 5000 - sound generation

You could no doubt do something similar with BeebOPL or BeebSID but you are limiting yourself to the capabilities of the original sound chip rather than taking advantages of their extra features. Not necessarily. ENVELOPE wouldn't necessarily be much use, but you could take the stream of notes gene...
by crj
Sat Feb 17, 2018 2:58 am
Forum: software: classic games
Topic: MIA Games on eBay
Replies: 79
Views: 1922

Re: MIA Games on eBay

Almost 5 years! Time flies when you are having fun! Mmm. I know I registered back then. (More exactly, I went on an archaeological dig for my registration details when I tried to register and discovered I already had.) I don't recall why, though. Let the record show my first actual post was on Sept...
by crj
Sat Feb 17, 2018 2:51 am
Forum: general
Topic: Today I received.....
Replies: 4430
Views: 274356

Re: Today I received.....

I actually received these on Wednesday, but have only just got around to taking a photo:

Image

Two model Bs courtesy of Lardo Boffin, and an Electron with Slogger ROM expansion, Slogger disc interface and a floppy drive courtesy of alan50.
by crj
Sat Feb 17, 2018 12:25 am
Forum: general
Topic: little optimistic???
Replies: 14
Views: 508

Re: little optimistic???

trixster wrote:There is no practical point to retro-computing other than the pursuance of a hobby that you enjoy.

There is also the heritage aspect, which is quite important to at least some of us. It would be good if anyone who wanted to in 2082 could still look at a BBC Micro.
by crj
Sat Feb 17, 2018 12:19 am
Forum: software: classic games
Topic: MIA Games on eBay
Replies: 79
Views: 1922

Re: MIA Games on eBay

CMcDougall wrote:only let the chosen few in, like >100 posts

>100 posts is the chosen few? I've apparently done 500 and I've only been here a few months!
by crj
Sat Feb 17, 2018 12:15 am
Forum: stardot.org.uk
Topic: Stardot logo fixed and now spud and banana free!
Replies: 57
Views: 802

Re: Stardot logo disappeared!

Hmm. It's Friday evening, and I'm seeing a spud, even after refresh. The mind boggles. (-8
by crj
Wed Feb 14, 2018 3:17 pm
Forum: programming
Topic: ADFS Format
Replies: 20
Views: 688

Re: ADFS Format

If this was not done the minimum unit of information that could be written to disc would be a whole track. On a standard Acorn DFS disc this is about 2.5K. That means if you opened a file for writing, for example BASIC's PRINT# and the like, the DFS would have to claim 2.5K of memory so it could ke...
by crj
Wed Feb 14, 2018 3:00 pm
Forum: wanted
Topic: BBC Micro Monitor Stand (photo inside)
Replies: 4
Views: 224

Re: BBC Micro Monitor Stand (photo inside)

Anyone have access to a press brake or other sheet metal bending facilities? I don't know about that specific model, but my experience back in the day was that the ones which consisted simply of of a bent bit of metal tended to gradually splay out. I never actually saw one collapse and land a monit...
by crj
Tue Feb 13, 2018 8:58 pm
Forum: software: games - high scores
Topic: keyboards on PC to play games: Ignored keys with other keys pressed
Replies: 13
Views: 326

Re: keyboards on PC to play games: Ignored keys with other keys pressed

Not complicated but it does cost a few pence more - it needs extra diodes. It looks like diodes are about a penny each in bulk, so it adds a pound to the cost of a keyboard... plus the extra assembly and testing work. Frankly, the simpler solution would be for someone to make an integrated keyboard...
by crj
Tue Feb 13, 2018 8:34 pm
Forum: hardware
Topic: BBC Master noob
Replies: 48
Views: 1094

Re: BBC Master noob

It's mono out (as it's only a single phono connector) - but just run it into a mono 3.5" jack and you'll be 'reet :) Um. I assume you mean a 3.5mm jack. 3.5" would be... large. (-8 Note that if you plug a mono jack into a stereo input socket, you'll get sound only on the left channel, wit...
by crj
Mon Feb 12, 2018 4:21 pm
Forum: for sale / freebies
Topic: Some cheap stuff for sale (all gone).
Replies: 11
Views: 534

Re: Some cheap stuff for sale (and a normally priced Competition Pro)

Ooh!

I do hope the fragile tape doesn't get damaged in transit. (-8
by crj
Sun Feb 11, 2018 10:00 pm
Forum: programming
Topic: Sideways ROMs, Ctrl-Break and running from SWRAM
Replies: 4
Views: 185

Re: Sideways ROMs, Ctrl-Break and running from SWRAM

sweh wrote:You might be able to fake it out with

Code: Select all

?&FE4E=127:CALL !-4

Handy hint: &FE4E is 65102 in decimal, which is nice and easy to remember. (-8
by crj
Sat Feb 10, 2018 3:30 pm
Forum: hardware
Topic: BBC Master noob
Replies: 48
Views: 1094

Re: BBC Master noob

BASIC is there, it just doesn't know to use it as the default language as the cmos is fudged. *CO. LANG. <romno> is what you use to configure it. In the meantime, *BASIC will take you to a BASIC prompt. That assumes scrambling the CMOS hasn't accidentally unplugged BASIC. *ROMS is a good first step...
by crj
Sat Feb 10, 2018 3:27 pm
Forum: hardware
Topic: Screen shadow memory
Replies: 18
Views: 505

Re: Screen shadow memory

Ooh! Rather more intrigue than I expected.

I assume it was hushed up a little at the time, but I'm surprised I never subsequently heard via my various grapevines. (-8
by crj
Sat Feb 10, 2018 3:22 pm
Forum: acorn atom
Topic: Atom on FPGA based retro-computers
Replies: 13
Views: 2344

Re: Atom on FPGA based retro-computers

That sort of thing is a big problem. I'm currently in the early stages of working on a product. If I pull it off, it'll be a lot of effort, therefore expense. I really need to recover my costs, and if it's a success then being modestly rewarded for my pains would also be nice. It would be really nic...
by crj
Sat Feb 10, 2018 3:16 pm
Forum: hardware
Topic: P.R.E.S. AP3 and &E00
Replies: 24
Views: 438

Re: P.R.E.S. AP3 and &E00

MikeKee wrote:I mentioned to my wife that I'd been married to her for 22 years but I'd had my Elk for 33 years.

She seemed unimpressed.

On sober reflection, one would really hope that anybody who got their Acorn as a kid has owned it for longer than they've been married!
by crj
Sat Feb 10, 2018 3:14 pm
Forum: hardware
Topic: Screen shadow memory
Replies: 18
Views: 505

Re: Screen shadow memory

So it is doing the switching in software, then? I don't know about the Solidisk board, but I believe the Aries unit provided a sideways ROM with the support software it. Presumably, they hooked the appropriate OS calls and switched banks under their feet. However, the BBC Master taught us that ther...
by crj
Sat Feb 10, 2018 3:05 pm
Forum: hardware
Topic: Screen shadow memory
Replies: 18
Views: 505

Re: Screen shadow memory

So far as I'm aware, the Aries board was the original shadow RAM, as an expansion for the model B. It pre-dated the model B+. Indeed, I've often wondered whether they were in cahoots with Acorn from the outset, or whether Acorn then borrowed the idea. Providing a second bank of RAM which can map fro...
by crj
Thu Feb 08, 2018 5:46 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 16
Views: 341

Re: Why did CISC prevail?

Also the Thumb instruction set didn't provide access to the floating point instructions Better ideas than Thumb: number 1 in a series of umpteen ad nauseam, by crj Define a 12-bit encoding for the most frequently used simple instructions. Define a 16-bit encoding for even more of the most frequentl...
by crj
Thu Feb 08, 2018 5:01 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 16
Views: 341

Re: Why did CISC prevail?

I think we should look to RISC-V for a possible future RISC contender. I don't think there will ever be a future RISC contender. At least, not one that contends on the basis of being RISC. Such a large proportion of code is now in relatively high-level languages that the hurdle for creating a new C...
by crj
Thu Feb 08, 2018 4:51 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 16
Views: 341

Re: Why did CISC prevail?

hence the Thumb instruction set The Thumb instruction set is a major bugbear of mine. I could rant a lot about it, but shall restrain myself. The one broad point I'll make is that if you look at it carefully and think about what's really going on, you'll likely spot that the technical advantages we...
by crj
Thu Feb 08, 2018 2:45 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 16
Views: 341

Re: Why did CISC prevail?

Everybody who's designing CPUs is engaged in a complex multi-dimensional tradeoff. When you improve one thing, you make something else worse. Code density is an issue for cache occupancy and instruction fetch bandwidth as well as memory usage, for example. Allowing more registers will make the CPU's...
by crj
Thu Feb 08, 2018 1:46 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 16
Views: 341

Re: Why did CISC prevail?

In fact, you could probably build an argument that ARM hasn’t been truly RISC since they added the MUL instruction ;) The ARM was never a purist RISC architecture. If you want to see what "true" RISC looks like, read up on the early MIPS chips. Even before MUL, the ARM had register-specif...
by crj
Thu Feb 08, 2018 3:35 am
Forum: hardware
Topic: Atari joystick interface for BBC Micro?
Replies: 10
Views: 231

Re: Atari joystick interface for BBC Micro?

1024MAK wrote:The common connection in an Atari (compatible) Joystick is common to all the directional outputs (up, down, left, right) plus the fire button.

Oh, yeah, duh. That was even more obvious than I was expecting. /-8
by crj
Thu Feb 08, 2018 1:46 am
Forum: software: other
Topic: BASIC weirdness
Replies: 9
Views: 299

Re: BASIC weirdness

Slightly beside the point, but that's still asking for trouble unless you can be certain the filename is short enough to fit in 2048 bytes with BASE_DIR prepended. If your system offers it, asprintf is your friend; if not, at the very least use snprintf and check for overflow! (Meanwhile, if BASE_DI...
by crj
Thu Feb 08, 2018 1:34 am
Forum: hardware
Topic: Atari joystick interface for BBC Micro?
Replies: 10
Views: 231

Re: Atari joystick interface for BBC Micro?

Hmm. I instantly jumpted to the perhaps-naive conclusion that all you needed for each channel was: ⋅ Resistor from VREF to the input ⋅ Equal resistor from GND to the input ⋅ One Atari joystick direction switch shorts VREF directly to the input ⋅ The opposite A...