User talk:Rasz pl

Video display controller
Hi, Rasz pl. I was editing the Video display controller article, and I noticed that there has been a bit of a dispute between you and over the deletion of sourced material. I wondered what was up, and looked up the editor who originally added the content, which led to this disussion at Administrators' noticeboard/Incidents. So it doesn't look that promising.

OTOH, currently the article doesn't cite any sources at all, so I wonder if there isn't something that be salvaged. For example, I took at look at this, which was deleted:
 * The Fujitsu MB14241 was used to accelerate the drawing of sprite graphics for various 1970s arcade games from Taito and Midway, such as Gun Fight (1975), Sea Wolf (1976) and Space Invaders (1978).(ref) (/ref)(ref) (/ref) Using a frame buffer system,(ref) (/ref) it was capable of displaying up to 60 sprites on screen,(ref)(/ref) and move up to 24 of them at once.(ref) (/ref)

Is there anything there that can be salvaged? There are 2 cites to GitHub, and they are probably correct, but GitHub is like a wiki, so not what we consider a reliable source. The book cite didn't mention this specific chip, so that's probably out too. (Although the book looked good and would probably support some of the other material.)

And so on. So that's what I was thinking of suggesting. How about if we go through this deleted material, check the cites, and see if there is anything that can be salvaged, despite the fact that it was added an apparently unreliable editor? There may be room for a compromise if there is something of value in there, if we can check it out carefully. Or look to see if we can find other sources to support this paragraph. If we found some, we might be able to put it back in. – Margin1522 (talk) 04:03, 17 March 2015 (UTC)


 * Hey. This Fujitsu MB14241 bit is total bullshit. MB14241 is doing IO on those arcade boards (reading buttons), it just integrates 8 74 series chips in one package (http://arcarc.xmission.com/Tech/Datasheets/mb14241.pdf). Data generated by this chip lands on the CPU data input bus. Video shifting is all discrete logic on another board altogether (http://www.robotron-2084.co.uk/manuals/invaders/taito_space_invader_l_shaped_board_schematics.pdf http://www.robotron-2084.co.uk/manuals/invaders/taito_space_invader_3_layer_board_schematics.pdf) 74161 generator + 74157 address multiplexer + 74166 deserialiser. There are no hardware sprites or anything.
 * I reverted because he didnt bother to even read what he was doing, and blindly mass deleted ~8 last submissions, including 3 legit ones
 * https://en.wikipedia.org/w/index.php?title=Video_display_controller&oldid=634826603
 * https://en.wikipedia.org/w/index.php?title=Video_display_controller&oldid=634828326
 * https://en.wikipedia.org/w/index.php?title=Video_display_controller&oldid=644281441
 * After his stupid edit page was visibly broken :/ - big hole in the middle of a sentence. If he would mention removing fact checked bad content I could simply fix his error, but it looked like witch hunt (banned user = lets delete everything and then some). I read enough horror stories about basement dwelling wiki overlords to just give up and stop caring. Rasz pl (talk) 01:05, 18 March 2015 (UTC)


 * Aha. So there were some legit ones. Too bad. If this page had 100 footnotes it would be really useful. How about if we put the legit ones back, with a note on the talk page? Have to start somewhere. – Margin1522 (talk) 01:54, 18 March 2015 (UTC)

I know this is from five years ago, but since I've just finished cleaning up all the mentions I could find of the Fujitsu MB14241 on Wikipedia, removing it from where it doesn't belong at all, removing the erroneous claims and misused citations for it, and explaining what the chip (and its discrete circuit predecessor) actually was, I thought I'd comment here as well, since you two had looked into this. My apologies if this is unwelcome, and be assured I don't want to refight an old mess.

The chip can't really be called a "video shifter" by the rough definition given in that article, nor is it a video display controller of any kind, but neither was it doing game controller I/O. (If you examine the game board schematics more carefully, you'll see that the chip or its discrete predecessor circuit responds to different I/O addresses than the game controls do.) It was actually a form of barrel shifter which had latching inputs and which the CPU used to properly bit-shift graphics data that it was about to copy to the framebuffer. As you said, the shifter sat on the CPU data bus: the CPU, after loading a shift count with an initial OUT instruction, would execute further OUT-instruction/IN-instruction pairs to feed it each data byte to be shifted and read the shifted data output. The CPU had to copy each shifted result to framebuffer memory to make the shifted graphic visible. Of course, this has nothing to do with the usual definition of video shifting, nor has it any relationship to a sprite engine.

The MB14241 chip itself was only used in later Taito/Midway 8080-based games, starting in later 1979 with Taito's Space Invaders Part II (branded as Space Invaders Deluxe by Midway). Before that game, there was instead a discrete circuit of multiple chips which performed the same task. In the earliest versions, starting with Midway's Gun Fight of 1975, this circuit had four AMD Am25S10 4-bit shifters and five 74175 quad D-type flip-flops, the latter of which served to latch the circuit's inputs. Most later versions replaced some of the 74175s with 74174 hex D-type flip-flops. A few games (notably Boot Hill of 1977) had a reversible version of the shifter which added a couple of 74157 quad 2-to-1 multiplexers for selecting either normal or bit-reversed output. Starting in late 1978 the circuit was changed again, with the four Am25S10 shifters replaced by eight 74LS151 8-to-1 multiplexers wired to act as a shifter—from the look of things, the Am25S10s were becoming unavailable. Finally the circuit was replaced by the single-chip MB14241 version.

The MB14241 schematic you linked to is really a schematic for a replacement circuit, in case someone has a failed MB14241 and wants to build a new one themselves.

If you want a more detailed (excessively detailed?) explanation, I've written one here.

--Colin Douglas Howell (talk) 07:09, 16 March 2020 (UTC)


 * Sorry, this is too long ago for me to pick it up again. But good luck in your research. – Margin1522 (talk) 13:35, 16 March 2020 (UTC)


 * No problem, I wasn't expecting either of you to pick it up. Just figured I'd mention it to you two as a sort of followup. --Colin Douglas Howell (talk) 15:02, 16 March 2020 (UTC)

May 2016
Please do not add defamatory content to Wikipedia, as you did to Matthew Santoro, especially if it involves living persons. Thank you. -- auburn pilot  talk  01:17, 8 May 2016 (UTC)

Rasz pl (talk) 05:40, 8 May 2016 (UTC) per wikis own definition defamation _is the communication of a false statement_