Hot answers tagged

29

Per Sophie Wilson: To prove that [Steve had] designed the microarchitecture correctly, he wrote, in BBC BASIC, a model of the microarchitecture. To prove that I'd designed the architecture correctly, I wrote an interpreter for the processor's instruction set and wrote programs in it. So, well before any actual commitment to doing things, we could ...


27

There are a number of optimisations which, in aggregate, will improve performance somewhat: There are multiple linked lists for the variables, one per first letter of the variable name. This makes name lookup faster compared to a more typical implementation with one linked list. The integer variables @% through Z% have fixed memory locations and do not ...


23

Sideways ROM (also RAM in later models) was paged into the processor's address space. Sideways memory sat in the address range from $8000 to $BFFF. The BBC Model B had four slots on the motherboard into which EPROMs could be put to occupy this space. One of the slots was reserved for BBC Basic. Expansion boards could be purchased to expand this to 16 ...


18

The red function keys were a carry-over from the days of the BBC's Computer Literacy Project. The first computers made for the BBC by Acorn, the Model A and Model B featured red function keys: These red keys were a feature of all "BBC" computers, including the subsequent BBC Master series. The first machines of Acorn's Archimedes line were the A300 and ...


17

Reading up on various preservation efforts, including the Center for Computing History's, and information collected on Andy Finney's and Adrian Graham's sites, it appears that the most difficult part would be physically reading the disks — the required drives were built in limited quantities. If you have one of the drives, it might be possible to connect it ...


14

Linear power supply was not a BBC engineering requirement by the time I joined Designs Dept in late 1981. Perhaps it was dropped well before actual production; I don't know if that was pushback from Acorn or experience with a prototype. But by late 1981, shipping some with linear PSUs was an unhappy compromise caused by : (a) demand much higher than ...


12

According to The Register’s history of the Electron, production had stopped before the Olivetti cash infusion; in February 1985: But the Electron, seen to be low on Olivetti’s list of priorities too, managed to hold on. “We will be continuing to sell the Electron this year and hopefully next year as well,” pledged Reid, still interim chief executive and, ...


11

The Electron outputs an analogue interlaced 625-line image, with a line rate of 15.625Khz. HDMI is a digital input, so cannot comprehend the Electron's analogue output. VGA is analogue but many monitors expect a line rate of 31 kHz. It's not impossible that your screen would be okay with 15.625Khz though, as that's the PAL standard, so you could at least ...


10

The RiscPC was Acorn's first to use a separate RAM bank for the video. It was intended that the video drivers would auto-synch to the monitor. However, there was often a failure to synch, leaving a blank screen. From your description, this is what you are experiencing. I would suggest turning off the auto-synch. This can be done with the screen blank ...


9

What does "POST" mean? On the RiscPC, "POST" stands for Power On Self Test. The POST sequence is performed on computers running RiscOS 3, and ensures that the computer is working properly before it starts up. If the computer fails this test, an error message will be displayed on the screen, informing you that there was a POST error. How do I know what the ...


9

It cost me something like $50 all up to connect my Electron to the TV using an RGB to SCART cable (this one from eBay) and an RGB to HDMI converter like the one pictured below: You can get this model from a bunch of different eBay sellers, under various different brand names, but they're all the same. I've tested it out with MODE 0 - MODE 6, and it seems ...


8

Yes. The BBC has a Motorola 6845 generating its screen addresses. That's a flexible chip, with which the developer has wide control over screen sizing and placement. The Electron has a custom ULA designed by Acorn to produce the same video address generation as the 6845 when configured in one of the built-in modes but its functionality is fixed. So on a ...


8

Seemingly predating that StarDot thread by a few years, I found this list of documents that includes "HardwareSpecification.txt", "BASICOutline.txt" and a few others that are "(c) Copyright BBC 1981" rather than copyright Acorn, or dated 1982 when the BBC Micro actually appeared. There are various details not from the StarDot thread, including: unused gate ...


6

It is possible to read the discs using the original Philips player and connecting it to a PC but it requires a low level SCSI driver to be written as the communication is so slow and would time out using the standard comms. The other option is to look at the Domesday86.com project that is trying to sample the discs using a standard laserdisc player by ...


4

This isn't really an answer to the question, but the comments repeatedly talk about Sophie Wilson's claim to be able to execute 100k+ ARM instructions per second. This is an impossibility on any normal 6502 and so she must have misremembered or the commenters must be misinterpreting what she said. However, it's hard to show why it is wrong in a comment. ...


4

Acorn's BBC Micro series is well known for the range of add-on processors ... ... however, other Acorn computers (the Atom, the Electron and the ABC range) did not have such an interface. So the Tube interface was not Acorn specific, but it was specific for the BBC range of computers. ... given that its predecessors ... did support them? Of course any ...


3

The original BBC Micro was designed very quickly and was subject to internal debate over its processor; the 6502 was already seven years old, and the tube appears to have been a compromise: they would ship the base machine with only a 6502 and could then experiment with the various newer processors on the market after the fact, demoting the 6502 to a mere IO ...


3

The Stairway To Hell history site seems to indicate that the BBC did indeed get involved officially with the nascent A500. Sophie Wilson, the designer (then known as Roger): "Because the original ideas for an ARM-based computer had been for a business machine, Acorn's traditional partner, the BBC, hadn't been involved in the project (neither had new owner ...


3

Personally I also found that running in MODE 7 (the teletext mode) was far faster than any of othe other screen modes. The video had to handle 20K of screen memory in MODEs 0-2, 16K in MODE 3, 10K in MODEs 4 and 5, and 8K in MODE 6. MODE 7 required just 1K. So, not only were screen updates massively faster, the hardware had to spend less time accessing the ...


3

Ebay have a special category for retro computers There is also the UK based https://www.sellmyretro.com/ were you can try to sell it. I am sure that most countries also have their local sites where to sell things like this. Also, serach the web i your local area for Acorn user groups. Even if they probably are more into the slightly newer Acorn computers, ...


2

Sorry for being vague, but I believe of of the beeb racing games (may be revs) hides some code on screen in the sky area. A couple of timer interrupts to change the pallet was much easier than the practically unknown at the time "virtical rupture".


2

You might want to check this site out. It appears there are a bunch of utilities that help "clean" the sound, the fact that these exist probably mean that these UEF files are especially sensitive to signal/noise issues. http://www.retroisle.com/others/acornelectron/software.php


2

Someone would most certainly be interested in this. Whether it's worth your while is the next question.


2

I believe that the bbc master turbo had a 4mkz 65c02 and ran basic 4, so expect better than 2X again. I don't know about 6809, but the BBC range had the fastest processing from their introduction until the Archimedes range took over even excluding the ARM processor that was developed as a BBC coprocessor.


2

Three contributory reasons: After the BBC Micro, Acorn were using their own processor They didn't need hardware to support other platforms Microsoft Windows hadn't cornered the market yet Using their own Processor In the 8-bit era, Acorn had used existing, off-the-shelf processors in their computers, predominantly the 6502. When designing the Acorn Proton ...


1

While there is no evidence that Acorn released a general-purpose co-processor, they did intend to (at one point). A review of the Archimedes line, in the August 1987 issue of Personal Computer World magazine, includes the following statement: So far Acorn has announced its intention to produce the following podules: 'Floating Point', a hardware ...


Only top voted, non community-wiki answers of a minimum length are eligible