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mizapf

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Posts posted by mizapf

  4. Posted

    On 2/16/2021 at 12:14 AM, Tursi said:

    I suspect it's just because the missile and UFO are not running as far as the software expects in the time allotted when at 50hz... if you shoot a little late you'll still get the explosion, but it's further down the screen, etc.

    This is also exactly what you see in MAME, so it is definitely a matter of 50/60 Hz. I recently tried it and wanted to post a screenshot, but this proved to be a bit difficult. ;-)

     

    • Like 1

  5. Posted

    1 hour ago, adel314 said:

    I know this is way out of date, but it helped me sort out some frustrating issues I had when carrying out some 40 bit subtraction and addition.   The lesson I learnt is that you can't rely on the Carry Flag when performing arithmetic larger than 16 bits.   The most reliable method I found was to use the overflow for arithmetic functions and carry for carry over to the next register.   For example:

     

    I'd probably calculate the two's complement of the second operand and use an addition.

     

    by the way, which register is the most significant? I guess R3 and R7 (otherwise, SB and JNO would not make sense).

  19. Posted

    9 hours ago, GDMike said:

    Yup..ti controller. But not so much that, but the Dr itself can't do double density, but it can do double sided.

    Oh, is that so? I don't know of drives that do not support double density; is that explicitly stated in the specs? The actually hardware-dependent features are 80 track (narrower tracks) and high density (different magnetic head). DD is just another encoding with smaller cells. As if you switched from Country Waltz to Metal.

     

    As for the TI controller, I'm still surprised how common it is still today. Before that topic came up some years ago, I honestly thought the TI controller was almost gone, hence, in my TIImageTool I set double density as the default. I switched to DD in the late 80es, I don't remember if I even waited for my original TI controller to fail before I got a new controller. We had quite a selection to choose from: Myarc HFDC, DDCC-1, CorComp, Atronic, BwG come to my mind.

     

    But it's probably too late to spend so many thoughts about floppies. 🙂

    • Like 1

  21. Posted

    2 hours ago, atrax27407 said:

    The HD disks can be (allegedly) as 720K disks if the high density hole is covered. I forgot that the drive I was using was a 720K drive.

    No, don't do that. The magnetic coating of the disk does not magically change when the hole is covered. And this is the reason why HD disks normally don't work in DD drives.

    • Like 1
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