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stepho

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Everything posted by stepho

  1. Mathematicians like to use radians (a full circle is 0 to 2*pi radians) because it makes exotic formulae a little bit simpler. Normal people use degrees (a full circle is 360 degrees) for historical reasons (ancient Babylonians used it, therefore we use it). Easy to convert between them: radians = degrees * pi / 360.0 degrees = radians * 360.0 / pi
  2. stepho

    Chess

    "A strange game. The only winning move is not to play. How about a nice game of chess?" Love that movie. Maybe use sound clips from the movie: "Would you like to play a game?"
  3. stepho

    Chess

    I've been avidly watching from the wings and check your new comments every day. I did an AI project for my 3rd year uni project (modified min/max on a game with probabilities for winning each move instead of clear cut win/lose moves, based loosely on the chess game in "The war against the Chtor" by David Gerrold). Sadly, much of my knowledge has gone to the bit-bucket but I can still follow most of what you write and am quite impressed. UI idea: Occasionally have the computer say the speeches from Berserk. Eg, "Intruder detected", "Destroy the humanoid". Might be IP issues but you get the idea. If used only very occasionally while waiting the the human player to make a move then it might surprise the human player enough to make a mistake (kind of like Kasporov and co kicking each other under the table).
  4. URL has moved: https://local.theonion.com/adulthood-spent-satisfying-childhood-desires-1819566783 "The only difference between men and boys is that men have to buy their own toys"
  5. I can totally understand Tod on this one - I've been there myself. Management/customers want A, B, C but there are only enough resources for 2 of them. That could be AB, AC or BC but not ABC. The resources might be cartridge size, processor speed, RAM or developer time. So he chooses 2-player mode and dedicates developer time and the meagre cartridge space to doing that. Which means he doesn't have developer time or cartridge space to do ghosts without flickering. If he'd dropped 2-player mode then he might have been able to flicker free ghosts Some of his other choices were obviously wrong - but obvious only with 20/20 hindsight. When you're one of the first to do it then you have no guidance about which is the "correct" way. He had no way of knowing how much the customers cared about colour choice or vertical/horizontal exits. And lastly, he took on a task that others had refused. To quote JFK, "We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard". Gotta admire a guy that takes on the hard jobs.
  6. My impression was that the 800 was the real computer and the 400 was the cut price version. I guess the intent was to bring in as many buyers as possible with the cheap version, then hope that they will create an eco-system to support the better version. These things were cheap compared to minis and mainframes btu still a significant cost to an average family - anythign that made them cheaper was a good thing. As for the worst keyboard... I remember using a friend's cheap MSX80 variant from Japan that had 2 controllers with about 20 keys+joystick each that could be put together to make a really crud keyboard. The IBM-PCJr had a pretty bad chiclet keyboard too. The article mentioned that Atari wanted a slice of the business market. But using only 40 columns and using home TV's for monitors made this a laughing stock. Even the C64 didn;t manage that one, leaving the market mostly to the Apple II. Then the IBM-PC wiped the floor with the entire home computer market - "no-one ever got fired for buying IBM".
  7. "How Atari took on Apple in the 1980s home PC wars" https://www.fastcompany.com/90432140/how-atari-took-on-apple-in-the-1980s-home-pc-wars Interesting pic of Chris Crawford playing Eastern Front.
  8. Many thanks. Finances prevent me at the moment but it certainly looks more tempting for the future.
  9. If only the missus and kids would see it the same way Much appreciated.
  10. For the tightwads among us who can't decide between buying the books or feeding the children this week (1), is it possible for you to put a small extract of the book for us to download? A sampler may help us to make the right decision at a future date. Note 1: I exaggerate, they get feed at least once a week
  11. Those opcode definitions look like prime candidates for an INCLUDE file.
  12. Thanks. But now I can't find any indication of price or cost of shipping to Australia - I'm not worried if it's super slow if it's cheaper
  13. For those of us late to the game, what is the website address? Thanks.
  14. Restrictive is when you are not allow to access something that is there. Other systems give you nanny chips that you ask to do something on your behalf. The VCS gives you access to practically everything in any combination that you can dream up. Which is how homebrew games still manage to come up with payable games after 40 years. It's a bit like having a F1 car that you can only drive on a race track vs a Yugo that you can drive almost anywhere (except possibly to a Mustang auto show). One is very powerful but very restrictive. The other is not powerful but not restrictive. Which one can you drive to the local shops?
  15. In Australia the VCS box included Space Invaders. But that was a few years after the initial launch. I think (but am not sure) that Combat was in the early boxes.
  16. I'm a bit out of my depth but a bit of bouncing around the net shows that the 2600 TIA is labelled UMC6526 while the completely different Commodore part is labelled MOS6525. I don't know if the P1 suffix is significant but I suspect the suffix specifies PAL (UMC6526P1) vs NTSC (UMC6526N). https://www.lemon64.com/forum/viewtopic.php?p=705874&sid=806bcfc57d1b24b9506836d8cccb4dff I'm sure there should be a chip parts list around here somewhere.
  17. Intermittent shorts are a common thing. Possibly something is loose inside and sometimes sits in a nice spot and sometimes sits in a bad spot. I would still open it up and look for anything obvious like wires coming loose or bits of metal or solder floating loose or a kinked cable (which often has internal breaks).
  18. Stephen, Both your method and mine should work. If there is a short to a paddle pin then measuring between the fire pin and ground would show a resistance above 0 but way below infinite. The resistance is of course from the path through the swipe arm and the track. Which will vary according to the position.
  19. Disconnect the paddles from the 2600. Put and ohms-meter (multi-meter in resistor/ohms mode, a cheap $10 meter from any electronics or car parts place will do) across the paddles' pins for the channel that moves. Press the button. If the resistance changes then you have a short between the fire pin and the paddle pin. Open up the paddle to see if any internal connections have worked their way loose or if something is bridging 2 connections. Connect the ohms-meter to the fire pin. Does it change it's resistance when the paddle is swept? Should be infinite resistance when the fire button is not pushed and 0 ohms when the button is pushed. Anything beside infinite and 0 means a short - same as above. Less likely that the cable itself is at fault but perhaps it has an almighty kink in it where it got pinched hard. That might have broken a couple of internal sheaths and allow bare wires to touch - the kink should be obvious.
  20. I've got an old Remington Remette portable. But it's the UK version with a funky top row (from when Australia still used pounds as currency).
  21. Ah-ha, I found it! First a history lesson. The first practical typewriter was the Sholes and Glidden typewriter, later known as the Remington 1 - it had uppercase letters and numbers but no shift key. Then the business was sold to to Remington and the 1878 Remington 2 was released - it had a shift key, upper/lowercase, numbers and punctuation above the numbers. In fact the top row starting from 2 (use a lowercase letter L for one and uppercase letter O for zero) was "#$%_&'() ASCII has these in order "#$%&'() being a direct copy of the most famous mechanical typewriter brand with just the _ being dropped. Most computer terminals went for the bit-paired order where the ASCII order was put on the top row and one or two logic gates could implement the shift key - easy and cheap! Most home computers followed the same convention, although Atari inserted the @ key after the ' key, which kind of cancelled out the earlier deletion of _ as far as the () brackets were concerned. Enter the electric typewriter in the form of the 1961 IBM Selectric. Each key had to use the same force, whether it was shifted or not. Which meant that 2 and " characters both got the same force. But the smaller " character has all that force being applied through a smaller area, so it appears darker and deeper on the paper when struck through the ink ribbon. Therefore IBM rearranged the keyboard so that each shifted and non-shifted character on any given key were similar in size and then arranged for particular keys to have slightly less force applied. So the ' and " were moved to their own key and @ and * were moved above the 2 and 8. The Selectric was copied by DEC, which was copied by the ANSI terminal, which was copied by the IBM PC keyboard, which then dominated the world. The final clue about the hammer force was found at http://www.quadibloc.com/comp/kybint.htm (about halfway down just after the images of key rows). The history of ASCII can be found by searching for "Bob Bemer" and "father of ASCII" - his website http://bobbemer.com/ has many interesting anecdotes about how many different character encodings were selected (often with his boss's politics overriding his technical reasons).
  22. This is starting to bug me - why did the " and @ swap places? I have already mentioned the DEC VT52 keyboard suing 2/@ (which was copied by the IBM-PC and hence dominating the computer industry). And as Urchlay said, most computer keyboards followed the ASCII order where simply changing one bit made 2/" logical. But why did DEC choose 2/@ ? I think they copied it from the 1961 IBM Selectric typewriter, which didn't have to be compatible with any code besides its own internal code that drove the golf ball font element. The Selectric was extremely common and well regarded (although expensive) in the business office. DEC terminals were meant to be used in office environments So it made sense to copy the keyboard that most typists were used used. Most terminals of the day were simple shift registers that could only modify a bit or 2 via the shift or Control keys using simple discrete logic gates but DEC terminals were among the first to have extensive logic which could really shuffle things around in arbitrary ways, so maintaining ASCII order wasn't a big problem for DEC. So, most home computers followed the layout used by most terminal manufacturers that matched the ASCII code order. And DEC (and hence IBM) followed what was used in business offices. But where did the 1961 Selectric get its layout from? The 1935 IBM Electric Model 01. Although this also had European variants with 2/" . And this also begs the question - why did ASCII choose that particular order? But I've probably gone deeper than you wanted, so I'll stop here unless asked. As always, history is never straight forward
  23. During the early days of terminals (1960's, 1970's) there was a lot of flux in the exact layout of terminals. Computer terminals needed more and different symbols (eg multiple brackets, less than, greater than) compared to business typewriters (eg 1/2, 1/4) The letters and numbers agreed with typewriters but everything else was not standardised and each manufacturer did their own variations. Many had agreed that " went on the 2 key but not everybody. DEC (aka Digital Equipment Corporation) decided to put the @ on the 2 key for its very successful VT52 terminal and the follow up VT100. The VT100 formed the basis of the ANSI terminal (guess who was on the ANSI committee for standardising terminals). Then the IBM PC copied the ANSI terminal keyboard. The 800 pound gorilla won the day and the others (including Atari and most other home computers) faded into history. Out university computer lab in the mid 1980's had a huge pile of hand-me-down terminals that had all sorts of keyboard layouts. We just had to get used to certain symbols moving around or try real hard to get the same terminal for each tutorial. Other countries tried to keep closer to their existing typewriter keyboards, hence the thought that "/2 is a UK thing. Plenty of pretty images of old keyboards at https://terminals-wiki.org
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