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Tony Cruise

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Posts posted by Tony Cruise

  1. Just for fun I made the mockup below. It looks pretty good in text mode, I think. The programmer could borrow a page from Pepper II and have an entire level spread out over 4 screens. There's probably enough room in VRAM to store a level, but the real problem is that Rogue requires a lot of RAM to store all the levels, because the player needs to backtrack to the surface once he finds the amulet in the deepest level.

    Rogue levels are procedural generated, so you don't need much ram to generate the shape/design of the rooms, just the state of items/enemies in the rooms.

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  2. The Coleco (like the MSX and other similar systems) have a separate graphics processor that has it's own work RAM of 16k, along with this the Coleco has 1k of normal RAM for the CPU (Z80) to use.

    The standard cartridge can have a maximum ROM size of 32k, which can contain, code, graphics and sound data mixed in any order (most launch titles only used 16k Rom cartridges - thus why titles such as Donkey Kong are missing a level). With compression it is amazing what you can fit in a 32k cartridge.

    As the main CPU is a Z80 it is capable of bank switching and there is a bank switching cartridge available that allows much large ROMS (up to 1Mb?), which can once again contain code, graphics and sound data.

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  3. Well for me my list is:

    1) Finish off the conversion of Pyxidis & Cavern Fighter so they can be released by Collector Vision.

    2) Keep working on secret project

    3) Start work on another new EA game from notes from many years ago.

    4) Track down some of the cartridges missing from my collection

     

    And some progress on the above will be made when I start holidays (hooray) in a few days time :)

  4.  

    According to this article: http://www.nintendolife.com/news/2010/09/feature_how_colecovision_became_the_king_of_kong

    Bromley states that he started the preliminary design & costing for the ColecoVision at least 3 years before it's release in 1982. So the beginning development for the CV was in effect at least by 1979. The only thing that throws me off is the GI sound chip. Maybe it was a typo....or maybe Coleco finally switched to the TI sound chip maybe for cost reasons? Anyone know for sure?

     

    Yeah see that's the thing, Colecovision were working on their own design for quite a while and it probably did use the GI sound chip (so probably both stories are right), but they were running out of time, so it was easier to get the working model off Spectravideo (which was their early design before through Nishi's contacts in Japan they then replaced the sound chip with the Yamaha one). It also probably goes a long way towards why the Coleco Bios has so many rough edges i.e. it was rushed.

  5. The Creativision is a design descendant of the TI-99/4A. TI were at heart a chip manufacturer and sought as wide a distribution as possible for their designs. The TMS99xx series of chips were very powerful and flexibly for when they were brought out. So the Creativision is a 6502 with accompanying TI-9918 graphics chip.

    The Z80 based architecture with the TMS991x chip and initial sound processor started with a design from the two designers (Hong Kong based Americans) of the original Spectravideo. Colecovision were working on their own design (with similar components) but could not get it work (this initial work then become the Adam) so bought the initial prototype design from Spectravideo. They then added their own BIOS, went to work on the early software titles, pushing their console out well before Spectravideo could launch their extensive range of machines and expansion units.

    Nishi of Microsoft Japan then took the design and showed it to a large number of Asian manufacturers, including Sega, trying to drum up support for a proposed 8-bit computer standard. Also early converts were Yamaha, who added the much improved sound processor replacing the original TI based sound solution. Sega went ahead quickly using the base design for the SG-1000, followed by the SC-3000 computer line (which actually ended up being released at the same time as the original Spectravideo).

    With support gathering from a large number of Japanese manufacturers, Bill Gates came fully onboard to support the MSX standard concept, allowing Spectravideo to work with Microsoft's Basic team merging features of Microsoft Colour Basic and Visual Basic (16-bit). Bill gates announced the MSX standard in advance of the official announcement in Japan.

    Some very minor architecture changes (merging the cartridge and expansion ports into the same interface) and changing the bank switching to allow up to 2Mb of memory, made Spectravideo having to re-release their machines with new models that supported the changes.

    There was a very well researched (proper interviews with most of the parties) article released by a UK publication recently for the MSX 30th anniversary. I'll have to dig up the URL and repost here for you to have a look at.

    All very interesting machines, I am currently collecting as many of the variants as I can find. I have most of them now, including a Creativision, a Sord M5, SC-3000 (& SC-3000H), Einstein all original Spectravideos, many MSX machines. Still missing a Memotech MTX though.

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  6. Got my copies today, thank you Tobie, you have done an excellent job, they look awesome!

    Two more big stand alone titles from me in a couple of months. One will definitely be a SGM title, as it was my biggest selling MSX title back in the day and deserves the full speed conversion and the other requires a bit more work to see if it will fit in 1k.

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  7. Yes with home brew releases, you can't really start using copyrighted characters and material when there still exists an active holder of that material. Even the current porting of MSX titles needs to be taken cautiously as Konami is still active in the market place.

    Now that an active community of home brew releases has been established I look forward to more original titles being brought out for the Colecovision. Yes they might take more effort than converting an existing ROM but they are definitely worth while. I especially liked Princess Quest and Quest for the Golden Chalice (yes I know based on Adventure for the 2600).

    There is no reason that one of the decent Batman platformers could not become an inspired game, changing the characters to something else but keeping the basic game play mechanics. Food for thought anyway.

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  8. Excellent work, demonstrates that there are lots of techniques to reduce the rom space used by screen layouts. I have a future game planned (after my original game conversions are all done) that will require quite a lot of data compression techniques like this.

  9. As the Coleco does not allow you to trap the CPU timer interrupt you do not have an accurate time figure and thus it's very difficult to generate a random number. The best way around this is to have a timer that is updated every VDP interrupt and have your game/demo start once a human presses a button or number on the controller i.e. the human generated random time period becomes the seed to your random number sequence.

    I use the following code to generate a random number, but it does itself need to be seeded with a starting value.

    ;
    ;   Generate a random number, based on the initial Seed
    ;   value.
    ;
    RND:
       PUSH HL
       PUSH BC 
       PUSH DE
       LD DE,(SEED+2)
       LD HL,(SEED)
       LD B,5
    RLP1:
       RR H
       RL L
       RR D
       RL E
       DJNZ RLP1
       LD B,3
    RLP2:
       PUSH DE
       LD DE,(SEED)
       OR A
      SBC HL,DE
      EX DE,HL
      POP HL
      DJNZ RLP2
      LD (SEED),HL
      LD (SEED+2),DE
      LD A,E 
      OR H
      POP DE
      POP BC
      POP HL
      RET
    
    

  10. I program all my titles only in ASM, using Context as the editor (as it allows both syntax highlighting and properly parses the output line from the assembler i.e. able to jump straight to error line).

    I use tniasm (version 045) as the assembler and BlueMSX as the emulator as it seems to work fairly accurately.

    My current MSX to Coleco conversions use a couple of the BIOS routines, but I am gradually replacing them with better performance versions that suit what I need. This also makes it easier for me to be able to reverse port the titles back to the MSX, original Spectravideo and Sega machines.

    For more information on VDP tricks look at the development forums at msx.org, as the Coleco's video processor is pretty much the same, just perhaps has slower video ram causing more potential corruption issues.

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