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paulscottrobson

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Everything posted by paulscottrobson

  1. That's going to be near mandatory or close to it anyway. Even if the data port is squeezable in (I'd rather the SPI !) then you have the insoluble (without different hardware) 64k VRAM limitations. Some things (e.g. 320x240x256) are just impossible. I would think an X8 version of an X16 game would probably have to use 16 colour rather than 256 colour sprites, and no PCM sound or just tiny snippets, or one shot loads, or you could double the scaling, or just the horizontal scaling. BBC Micro games generally ran in 160 x 256 resolution and it did look a little chunky at times, but usually was fine.
  2. Maybe lose some of the sprites. There's 128 of them, I think, and Sprites are notoriously heavy on FPGA resources. 64 might do, thinking of all hell breaking loose games like say Robotron. Even then I suppose you could have an Amiga type construct where you had slow bitmap sprites and fast hardware sprites.
  3. Interesting. What are you doing ? Most of the game code I've seen is doing what you would expect ; either characters or tiles (in practice the same thing) sometimes overlaid with sprites which you manipulate by writing to the sprite registers, scroll registers (though I don't recall a scroller, it shouldn't be difficult). Sometimes there's no real background (e.g. SHMUPS) I did look at other ideas, mainly thinking about how you would implement such ideas. Vera is a bit NESish in that it's very good at what it's good at, but much less good at other things. I've often wondered, how would you do Asteroids, how would you do Frogger ? Michael and I have independently written line drawers which obviously access VRAM directly, and they're about the same speed, and I don't see how you speed it up much without the Window which gives you access to the full 6502 indirection thing almost. Frogger you'd probably have to do with line interrupts and scrolling, but it's a bit messy and won't work if you want varied vertical scrolling obviously. I think the code is going to be similarish because the hardware is very similar. Whether you write to the Tile/Sprite Control registers directly via the window or indirectly via $9F2x really doesn't make a huge amount of difference. PETSCII robots allows it because the base level, the PET, you can do on just about any 6502 machine that has the physical space and *some* form of graphics.
  4. Kim Justice's stuff is very good as well.
  5. Isn't it just a Pi / FPGA in a box with a fake non-keyboard so it looks like a baby A500 ? And why would anyone want an authentic Amiga mouse ; I mean when we didn't have modern mice we thought they were all right, but looking back, almost any ultra cheap mouse would be better ..... there might be interest in a real Amiga clone I suppose with a proper keyboard like the Max ?
  6. No, I much prefer the window. Compatibility isn't difficult - 98% of the time it is just loading stuff in to VRAM, which is part of the Kernel anyway (or should be !), and you may of course want different resolutions and/or sprite colour depths. And you can do stuff with the Window you can't do with the pipe. Programmers should be seperating their view anyway, so you can do what Dave has done with his Petscii Robots game, port it fairly easily. And well all keep our Models and Views seperate ..... of course
  7. Perfectly reasonable, but so is the silence. Dave tapped the community, got a response, has probably read some of the discussions, most of which were fairly predictable, and he'll make a call with input from other senior project members. It's a difficult call and wouldn't be helped by any more speculation on his part. We can talk about it all we like of course That can be helpful ; I would hope if they are going down the X8 route they've taken note of the things Bruce (mostly) has written about an SPI port.
  8. I never was quite sure how it actually got keyboard input. I've only done it on Microcontrollers, Arduinos. There was a block on making a cheap serial terminal for a long time because people could get it generating video easily enough, and reading PS/2 was a standard library, but not at the same time, until the 1284 (?) had a seperate asynchronous clocked input. I always thought you had to poll it if you didn't use an Interrupt.
  9. Possibly the most successful was the Australian Microbee, which was published in a magazine and ended up being the Australian school's machine, as did the Galaksija in the former Yugoslavia. Some of them were excellent, but they had the same problem retrocomputer projects do now, a big enough user base to produce software. Which is not a problem if you just want to tinker, of course. I think the first three computers I had I had one commercial game ...
  10. Fair enough, though the latter sounds to me like "adding an MCU to cope with the problems of timing". The Sinclair QL did the same thing, with an 8049, which would be 1984ish (it was a bodge OTOMH) so it's certainly period useable. So really are the FPGAs which are just very grown up user programmable ULA and specialist chips. It's the same idea ; put lots of complex circuitry in one chip rather than having a rats nest of wiring, albeit created differently. But then you get back to the same problem. Do you really have a machine where you can understand how it works ? Does it have any educational value at all as hardware ? And how much of it are you just treating as "a black box which does stuff" ? If you want to really understand how it works you'd be better of with Nand2Tetris or the Ben Eater computer. Or both.
  11. Have you had a look at the source ? I remain unconvinced. Apart from problems like the use of the Z-register there's a whole Z80 emulator in there. It's not very clear what any of it actually does and I can't find any real effort to seperate Mega65 specific code from generic code. It also seems to follow the modern tradition of comments being for wusses. Even if it works, it looks in the "nightmare to maintain" category. https://github.com/MEGA65/open-roms
  12. This is the basic argument. It's not practical to produce a serious video system without some dedicated chips - even in the early 1980s we had 6847, 6845, 99x8 and various ULAs in machines or dedicated chips. VDUs built out of TTL and RAM chips with an EPROM character generator tend to be late 1970s/early 1980s and many of them used a CRTC. Dave's original idea, which was to produce something cheap out of real parts always was impossible unless you took a Galaiksjan approach to video generation, and while this is very interesting, is limited. So there's a compromise, which is essentially video on one chip, and everything else with real parts. The main problem with this seems to be timing, which seems to have caused various other CPLD and MCUs to be added (not sure exactly what), and some things moved to Vera. So sound is now on Vera, and it's a moot point whether there's an advantage in having a real sound chip as well. The PS/2 keyboard interface was supposed to be done over the PIA as well, never quite sure how/if that worked given it's a slow clock. It wouldn't surprise me if that moves onto Vera as well. Then you could get to the point where you've pretty much got a standard 6502/RAM/Flash ROM reference design with all the add ons on an FPGA, with other modern components forming a bridge. It's supposed to have educational value (I understand the kit builders enthusiasm) but I've actually done this with real children in schools (usually doing on the fly repairs of BBC Micro Keyboards), and there's not a huge amount you can say other than this chip does this, this one does this and so on. it undoubtedly helps bridge theory and reality but they can't experiment with it.. They all look much the same but it takes a few minutes. If you want to get down to the nitty gritty of hardware you'd be better off with Ben Eater's course which is first principles parts but no sort of development platform (as yet) or a basic digital electronics course, if they still do these ? If you want real chips on there it'd be better to take a leaf out of Alan Sugar's book with the CPC472 and do it on an FPGA and just plonk fake components on. Then you can buy cheap fakes from China and it doesn't matter if they don't work.
  13. Often you have to make choices. Resource limitations force poorer quality emulation. The CX16 itself has the problem that it has hardware based sprite collision detection, which is easy enough in electronics but a complete pain in the neck in code if you want bit level accuracy. I don't think the emulator does it, it certainly didn't. There is a case to be made for removing it for precisely this reason. Backwards to this is the X8 Window, which is not difficult in FPGA but would be a swine to do in logic.
  14. Appears to be triggered by the cases becoming available. Electronically it's not complex, it's a Nexys A7 board with some add ons electronically. I don't think it's really a competitor for the X16. I'll be surprised if it's as low as $600. Developing for an M65 is much more complicated than an X16/X8 which is really just a tarted up C64
  15. I do remember the PE "Champ" 4040 machine which was built on veroboard ....
  16. The obvious thing to add to the X8 early on is an ESP32. Apart from the I/O ports, this also gives you Wifi, Bluetooth, and it also has a data transfer protocol ESP-NOW which I have tinkered with a bit and seems fairly simple and reliable, and talk to it over SPI.
  17. Yup, the price will be interesting. The devkit version was basically $1k. I'd guess $799 or $899 myself Wouldn't surprise me if it was more than the devkit.
  18. I think 250 for the X8 is a bit pessimistic, thought it matters less because it's the easiest to physically implement I think. If it's being sold at £50-£100 I think many people would buy it even if they bought an X16 as well. It's almost a beer money purchase.
  19. You should be using tag strip , get with the times.
  20. Well, Dave said he'd invested 5 figures and that Peri had invested 4 figures. I'm not sure how much actual cost there is in the development. I'd got the impression, perhaps wrongly, from comments that it was done for nothing or for a share of any profits. Parts cost can't be huge. PCB costs, didn't think they were ridiculous. Pre-paid the licensing is a possibility I suppose. I wonder if a decision will come sooner rather than later. One consequence of the original post will be some developers will be wondering if the machine they are writing the game for will ever exist, especially if it is Vera heavy stuff. There's something special about seeing one of your games on a real piece of hardware.
  21. ... I thought they were selling the customised version, my bad
  22. I wondered how much of the deficit went into keyboards. I never could fathom out the compulsory keyboard, I mean what about non US people ? I find US keyboards (@/" swapped round compared to the UK the main difference) irritating, so a French person with their AZERTY layout would probably end up throwing it out of the window. And personally, if I was going to use the thing rather than look at it, I'd swap the keyboard anyway, just so it didn't get damaged, I'm fairly rough on keyboards and I also like the split arced ones that I think Microsoft did first. I do wonder about how that affects the price. If the price of the kit is $250-$300ish a custom case and keyboard would probably do a large chunk of that on its own, and at the X8 price you are probably bare board level. Which is fine, screw it to a bit of perspex or something.
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