Talk:Acorn Electron

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Clock frequency[edit]

The article notes The Electron is widely misquoted as operating at 1.79 MHz after measurements derived from speed testing against the thoroughly 2 MHz BBC Micro for various pieces of 'common software'

I'm guessing, but I suspect the 1.79 figure is much more "real" that this comment suggests. The number is 1/2 the color clock (I think) frequency of a standard NTSC television. If one does NOT use this speed, the processor will end up accessing memory at the same time as the video circuitry. This is why the Electron ran so much slower when running software from RAM for instance.

So basically it's almost certainly true that the Electron DID run at 1.79 on NTSC, slightly slower on PAL, and perhaps 2.0 on a monitor -- but I doubt even that. The same numbers can be seen throughout the home computer world -- the Atari was the same speed, most other machines exactly half at .96ish.

Maury 12:58, 16 October 2005 (UTC)

On the contrary, the Electron Advanced User Guide (which could be found in PDF at http://www.astro.livjm.ac.uk/~bbcdocs/essentials/Eaug_pdf.zip but at the minute there seems to be an error accessing that file although the site that provides the link http://www.bbcdocs.com remains online) contains this text on page 212 of the PDF, 207 of the real thing (I have a copy):
Modes 4—6
The processor will normally be running at 2MHz when it first needs to access RAM or peripherals like the 6522. It has to slow down to 1MHz first. This slow down either consists of a PHI OUT low time of 250ns followed by a high time of 750ns, or a low of 250ns followed by a high of l250ns. The particular type of transition which occurs will depend upon the relative phases of the 2MHz and 1MHz clocks, This is illustrated in figure 15.1. Both the 1MHz and 2MHz clocks are internal to the ULA, and are not available outside. They must be generated separately (see later in this section).
Modes 0—3
In these modes, the ULA must have access to the RAM for all the displayed part of a line (40μs out of 64μs in 256 lines out of 312). This doesn’t matter provided that the CPU only wants to access peripherals and the ROM, which it is free to do in the normal way. However, if it tries to access RAM the the ULA will hold it’s clock high for up to 40μs. The overall effect is that the processor can be effectively disabled for up to 40μs. The only way for the processor to obtain priority over the ULA is by an NMI being generated. This will automatically cause the ULA to release the 6502 (and the RAM), but inevitably creates snow on the screen.
Besides specifically stating the 2 and 1 Mhz numbers and giving bus timings to corroborate, it is clear that the Electron outputs its 80 byte pitch display modes (modes 0-3) at a rate of 2 bytes (= between 4 and 16 pixels) every microsecond, so apparently does not conform to the NTSC colour clock in any way.
As a purely incidental point, I wasn't aware that there was ever an NTSC version of the machine. Do you have any information that there was? ThomasHarte 00:35, 16 November 2005 (UTC)

I am right in thinking that the different clock frequences mentioned in the article misleading? Surely the clock isn't actually switching frequences, which would involve some pretty advance chipped design. And doing it whenever the program counter switches between RAM and ROM seems... impractical. The way other machines of the time handled this was simply to lock the bus when the the video was accessing the memory, which is NOT the same as halving the clock frequency.

No, the clock supplied to the CPU does actually change frequency, or even simply stop for up to 40 μs. The ULA is generating both 2 Mhz and 1 Mhz clocks at all times, so it is fairly trivial to just switch between which is being sent to the CPU.
A PDF of the original Advanced User Guide seems to now be available from http://www.bbcdocs.com/ - check "Essentials" then scroll right the way to the bottom of the page. Besides the text directly quoted from it already on this page, to quote a little more from page 207/212 (including some parts of the chunks above):
When the ROM is being accessed, the 6502 runs at the maximum possible speed of 2MHz; PHI OUT is low for 250ns and then high for 250ns ... [w]hen RAM or peripheral devices are accessed, the timing will be highly dependent on the display mode. ... [in modes 4-6 the processor] has to slow down to 1MHz ... [t]he particular type of transition which occurs will depend upon the relative phases of the 2MHz and 1MHz clocks. ... [In modes 0-3] the ULA must have access to the RAM for all the displayed part of a line (40μs out of 64μs in 256 lines out of 312) ... if [the CPU] tries to access RAM then the ULA will hold it’s clock high for up to 40μs. The overall effect is that the processor can be effectively disabled for up to 40μs.
ThomasHarte 11:03, 30 January 2006 (UTC)

Can I respectfully suggest that, apart from the history section, the article be phrased in the present tense. I note that the article is phrased in the past tense throughout, which is a little confusing, since the machine still exists. FOr example, the article starts "The Electron was able to load and save from cassette..."... It still can! Clearly the history section of the article should be written in the past tense, but I see no reason why the article should use past tense elsewhere. I'm sure there are probably over half a million examples of the Acorn Electron still in existence! I did not edit the article (apart from two words in the opening paragraph) as I did not author it and do not believe in just going straight in and editing without getting a feel for others opinion. ANd anyway, I don't think my Wikipedia skills are up to it. I'm struggling with the user interface!

Fair use rationale for Image:ElectronBASIC.png[edit]

Nuvola apps important.svg

Image:ElectronBASIC.png is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in Wikipedia articles constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.

Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Wikipedia:Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.

If there is other other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page. Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.BetacommandBot 05:01, 3 June 2007 (UTC)

Screenshot gallery[edit]

There was (for over 2 years) a small gallery of 12 screenshots depicting a selction of the hundreds of games available showing popular games and different styles of graphics available for the machine. Since the vast majority of Acorn Electrons were used to play games, this is extremely relevant to the article. I see no reason why they should be deleted without debate but that is what has happened and no matter how hard I try to get the user to explain to me why, he simply re-deletes the section and threatens with reporting etc. He did quote one policy that seems to me to entirely justify the images:

WP:NFCC#8 Significance. Non-free content is used only if its presence would significantly increase readers' understanding of the topic, and its omission would be detrimental to that understanding. Non-free media files are not used if they can be replaced by text that serves a similar function.

The screenshots DO add significantly to the article. A quick glance gives the reader a much better understanding of the graphical capabilities of the computer and the type of programs that were commonly used. The omission of any screenshots IS detrimental to the understanding of the Acorn Electron. There is no text that could as accurately convey the same meaning.

A variety of shots is necessary. Any more would be excessive as they would not all fit on the screen for comparison but as it is, it is a perfect, descriptive illustration of what the Acorn Electron was (and is!). Retro junkie 11:20, 30 August 2007 (UTC)

A single screenshot might be useful as an illustration of the machine's general capabilities, but multiple screenshots do nothing to further that understanding - they just tell the user that "there was another game with a similar level of graphics that looked like this, and another one, and another one, and nine more".
It would be much more useful to write in detail about the different types of games and graphics supported by the Electron, than to present the reader with a handful of screenshots and leave them to try to make their own conclusions. --McGeddon 11:46, 30 August 2007 (UTC)

The gallery was used in a similar way to the Gaming history section on Commodore_64_software. Would it be better to structure it like that with a couple of lines of text in between? (btw a seperate Acorn Electron software article would be unnecessary). I see the point raised elsewhere about fitting them into the text where appropriate but I still think an at-a-glance overview of 6+years of screenshots adds a better understanding of the range of software eg the increase in detail from simple early games like Arcadians to the complex Holed Out 6 years later. Other shots showed 3D wireframe graphics, isometric 3D (from a game that probably does not merit its own article so that screenshot will be lost), monochrome, different graphic modes, the memory displayed on screen, conversions of popular multi-platform and arcade games (a quick reference for people familiar with other versions of the games) etc and were laid out chronologically.Retro junkie 13:24, 30 August 2007 (UTC)

  • No, that usage on the Commodore_64_software is also a violation of our policies. That's very, very heavy overuse of fair use images. --Durin 13:40, 30 August 2007 (UTC)
    • OK to be fair, I also think that is overuse. It is also untidy. In comparison, the gallery here was neat and fitted onto one screen. I would still like to be shown the policies that deal with multiple images, galleries etc.Retro junkie 15:21, 30 August 2007 (UTC)
      • You've been shown already. You disagree with the interpretation. Since a rather large body of users have interpreted it opposite to your interpretation, I recommend you take it up at Wikipedia talk:Non-free content. --Durin 15:44, 30 August 2007 (UTC)
        • WP:NFCC#8 quoted above does not apply. There is nothing there about galleries specifically. It is also purposefully subjective so I don't see how it can be quoted as if it is 'law'. I have told you how I think the gallery was appropriate, I would appreciate if you can spell out why you think it is inappropriate (and possibly replace it with text).Retro junkie 16:08, 30 August 2007 (UTC)
          • I'm not going to debate this endlessly. I'm sorry. If you want to learn more about this subject, please go to Wikipedia talk:Non-free content and read. #8 specifically banned galleries some time ago. There was a discussion on removing that specific case because citing examples created a situation where if an example case was not cited, then it was ok (see [1] "example bloat"). Thus, it was removed. But, the policy *did* state it at one time (see #8 as of this revision, and still implies it. This policy does not support your position as you think it does. --Durin 16:18, 30 August 2007 (UTC)
            • OK, thanks for clearing up where you are coming from but aside from that no longer being included in the policy, it still did not suggest that ALL such galleries should be deleted. I'll quote it here for easy reference: The use of non-free media in lists, galleries, and navigational and user-interface elements is normally regarded as merely decorative, and is thus unacceptable. The word 'normally' is important there. As I have tried to put forward, the gallery in question was not merely decorative. It served a genuine purpose.Retro junkie 16:28, 30 August 2007 (UTC)
              • It served a purpose, yes. But the article isn't amazingly lacking since it gallery's removal. I'm sure Durin would not object to, perhaps, adding one or two photos back in to illustrate, without adding the whole gallery back? --Deskana (apples) 16:33, 30 August 2007 (UTC)
            • If it's been there two years, like you say, I'm sure glad it's gone now. --Deskana (apples) 16:25, 30 August 2007 (UTC)
      • OK how about a compromise? I had an Acorn Electron too, and I loved playing games on it, but perhaps 12 screenshots is a bit excessive. How about you pick 2 or 3 screen shots and use them? I suggest perhaps one game shot, showing it in full power, and one non-game shot, and maybe one other exotic shot e.g. a demo scene. It is not necessary to show the different generes of games - all home computers have these, and that is a wiki article in its own right. Also it is not necessary to show games becoming more complex over the years - again that is common to all game-playing computers. Stick to showing what is special about the Electron, its essence. RedTomato 19:25, 5 September 2007 (UTC)
I think there's a good case for having shots both of one game from around 1984–5 (illustrating the quality of games available at the height of the Electron's popularity) and one from 1989–90 (illustrating what the machine was ultimately found capable of). —Blotwell 02:26, 6 September 2007 (UTC)

WD floppy controller?[edit]

Was the FDC a WD1770 or a WD1771? I moved the WD1770 page to WD1771 because it was describing the earliest WD FDC chip, which was the WD1771. The WD1770 came much later. But I have no idea which the Acorn used. --Brouhaha (talk) 21:13, 2 February 2008 (UTC)

Electron Add-on: MODE 7[edit]

The one I have is from Jaffa Systems Ltd. MODE7 Mk I (C) 1987; Same full width as the Acorn PLUS1, used both CRT6845 and SAA5050 was sold as a kit or ready built.

A later revision was the MODE7 Mk II (C) 1989; Smaller card, ONLY used the SAA5050 and not CRT6845.

The Mk II and the MODE7 Emulator ROM both used the Slogger's Turbo or Master 64K for speed!

For pictures of both MODE7 hardware types see:- http://www.bygonebytes.co.uk/Teletext1.jpg then http://www.bygonebytes.co.uk/Mode7.html

To double check this information, look in the Electron User, see the old adverts, then read the reviews!!

There was also another MODE7 add-on advertised in one of many magazines for the BBC / Electron Micros.

>> It's a shame that the main page, keeps deleting this historic facts! << —Preceding unsigned comment added by An Electron User 188.221.111.58 (talk) 11:12, 31 January 2010 (UTC)

Discussion at Template talk:Acorn computers#Proposed move/new title[edit]

You are invited to join the discussion at Template talk:Acorn computers#Proposed move/new title. Trevj (talk) 18:03, 18 October 2011 (UTC)