Frozen Fish 1: Amiga/FrozenFish-Apr94.iso/bbs/alib/d5xx/d555/thea64package.lha/TheA64Package/A64Utils.lzh/Doc/GrafixMenu

Text File | 1991-10-02 | 20KB | 568 lines

THE GRAFIX MENU


COLORS

    For a complete description of the COLORS option see the COLOR
    SCREEN section.


BORDERS

    KEY SEQUENCE: None

    The BORDERS menu option allows you to toggle the C64's borders on
    and off.  Because the Amiga does not support a true border around
    its screen, a border around the entire C64 screen can not be
    emulated efficiently.  To support programs that need borders, for
    such things as changing the border color to signify some status
    within the program, A64 supports a border on the top and bottom
    of the screen.  Changing the status of the borders will have no
    effect on the operation of A64, but may make some programs look
    better.

    The BORDERS menu option has two settings: ON and OFF.  You can
    select one or the other of these settings and selecting one
    automatically unselects the other.  The current selected setting
    is shown by displaying a checkmark next to it.

    When ON is selected A64 will display a border at the top and
    bottom of the C64 screen.

    When OFF is selected there will be no visible border on the C64
    screen.

    NOTE: The borders will not be visible until you exit A64 Prefs to
          C64 mode.


SCRN REFRESH

    KEY SEQUENCE: None

    The SCRN REFRESH menu option allows to change the way and speed
    in which A64 draws the C64 screen.

    When selecting SCRN REFRESH you will be prompted with a requester
    containing several gadgets.  The function of each gadget is as
    follows:






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SCREEN REFRESH TYPE GADGET

    A64 is capable of drawing the screen in two distinct ways and the
    SCREEN REFRESH TYPE GADGET allows you to switch between these two
    methods.  This gadget has two settings: DIRECT and SAMPLE.
    Selecting DIRECT will force A64 to use DIRECT MODE and selecting
    SAMPLE will force A64 to use SAMPLE MODE.  The meaning of each
    setting is as follows:

DIRECT MODE

    When A64 is in DIRECT MODE it writes to the Amiga's screen
    directly.  This means, when the C64 is performing an operation
    that changes some part of the C64's screen A64 make the same
    change immediately to the Amiga's screen.  This way of drawing
    directly to the Amiga's screen has the advantage of showing
    changes of the C64's screen immediately resulting in smoother
    screen updates, but has the disadvantage of having the tendency
    to slow down A64 when alot of changes are happening to the C64's
    screen seemingly at one time.  For example, scrolling in games.
    DIRECT MODE is the default setting for the way A64 draws the
    screen and it is suggested that you try using this setting before
    trying SAMPLE mode for most C64 programs.

SAMPLE MODE

    When A64 is in SAMPLE MODE it draws the changes in the C64 screen
    at a set SAMPLE rate.  This means that A64 will sample the C64
    graphics at a certain rate to see what has changed and then draw
    the changes.  This way of drawing the screen has the advantage of
    being faster when alot of changes are happening to the C64's
    screen seemingly at one time.  For example, scrolling in games,
    but has the disadvantage of making the screen updates appear
    jerky and at times out of sequence.

    NOTE: Out of the two ways of drawing the screen, SAMPLE MODE is
          the most compatible with the C64.  It has the ability to
          handle up to 25 raster IRQs per screen, spaced as little as
          1 scan line apart, while DIRECT MODE can handle up to 25
          raster IRQs per screen, spaced as little as 8 scan lines
          apart.  Although DIRECT MODE has this limitation, it will
          handle most C64 programs with no problems, but if you do
          encounter a C64 program where the screen does not look
          like it should try switching to SAMPLE MODE to correct it.









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SCREEN REFRESH RATE GADGET

     The SCREEN REFRESH RATE GADGET allows you to change the rate in
     which A64 checks if it should redraw the C64 screen.  This
     gadget is a string gadget and it allows you to enter a five
     digit number that corresponds to A64's screen refresh rate.
     This number can range from 1-65535 and the way A64 interprets it
     is as follows:

     A64 uses the SCREEN REFRESH RATE value as a countdown to check
     if it should redraw the screen.  A64 subtracts 1 from this value
     60 times per second and when the value counts down to 0 A64
     resets the counter and checks if it should redraw the screen.
     Depending on whether SAMPLE MODE or DIRECT MODE is selected and
     on what changes the C64 has made to its screen A64 will decide
     whether or not to redraw the screen.

     For example if you set this setting to 1 then A64 would subtract
     1 from it 60 times per second (1-1=0) and would result in A64
     checking if it should redraw the screen 60 times per second.

     See: REFRESH RATE TABLE in the GRAFIX section.

OK AND CANCEL GADGETS

    Selecting OK will preserve all changes to the SCRN REFRESH
    settings and selecting CANCEL will ignore any changes and abort
    the operation.

    NOTE: Both the SCREEN REFRESH TYPE and SCREEN REFRESH RATE
          settings can have major effects on A64's speed.  We suggest
          you play around with these settings while using different
          C64 programs to see their effects.


RASTERS

    KEY SEQUENCE: None

    The RASTERS menu option allows you to change some settings
    related to the video scan line.

    When selecting RASTERS you will prompted with a requester
    containing several gadgets.  The function of each gadget is as
    follows:

SCAN LINE READ GADGET

    Before explaining this setting we need to explain some basic
    principals of video circuitry and how the C64 uses them.  Inside
    your computer's monitor (or TV) is an electron beam that sweeps


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    across the inside of your monitor's picture tube, refreshing the
    picture as it goes.  This electron beam sweeps across the screen
    from left to right and refreshes the screen one horizontal line
    at a time.  This horizontal line is called a scan line.  The
    standard NTSC screen is made up of 262 of these scan lines.  This
    process of refreshing the screen, one scan line at time, happens
    very rapidly.  It takes your monitor 1/60th of a second to
    refresh one entire screen.  This means that in one second the
    screen will have been refreshed 60 times.

    Inside the C64 is a pair of registers (memory locations) that
    contain the current scan line number that is being refreshed by
    the monitor.  These registers are used by MANY C64 programs for a
    variety of purposes.  Seeing how these registers change at a
    regular rate many C64 programs use them for timing.  Another
    popular use for these registers is for a program to wait for a
    specific scan line before continuing.

    A64 is capable of handling reads of the scan line registers in
    two ways and the SCAN LINE READ GADGET allows you to switch
    between these two methods.  This gadget has two settings: REAL
    and FAKE.  The meaning of each setting is as follows:

REAL

    When the SCAN LINE READ GADGET is set to REAL, A64 will use the
    Amiga's hardware to get the current scan line.  This method is
    the more compatible of the two and should be used whenever
    possible.  There is one problem with using this method.  Because
    of internal timing in the Amiga some scan lines can not be read.
    Because of this, if a C64 program is waiting for one of these
    scan lines it will lock up waiting for something that will never
    happen (You can either select FAKE, described below, or reset A64
    to unlock the program).  Because of this problem A64 supports
    another way of reading the scan line registers, explained below.

    NOTE: It has been reported that with certain video devices
          connected to your Amiga, like GenLocks, A64 will fail to
          run with the SCAN LINE READ gadget set to REAL.  Because of
          this problem the default setting is FAKE, but if you do not
          have one of these devices connected to your Amiga you
          should switch this setting to REAL.

FAKE

    When the SCAN LINE READ GADGET is set to FAKE, A64 will simulate
    the function of the scan line registers.  This method will allow
    some C64 programs to run that wouldn't ordinarily with the above
    mentioned REAL method.  This method will allow all scan lines to
    be read, but because of the fact that it is a "fake" reading it
    will not be in sync with the true scan line.  This will not cause


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    major problems with most C64 programs, but it will throw off the
    timing of any program that uses the scan line registers for that
    purpose.

ROUND SCAN LNS GADGET

    The C64 has the ability to change its graphics modes many times
    during one screen.  Because of a minor incompatibility with a
    small number of C64 programs A64 may not change graphics modes
    at the exact scan line that the C64 intended causing garbage
    graphics data to appear in a couple of scan lines on the screen.
    The ROUND SCAN LNS GADGET will allow you to correct this problem
    with some programs.  This gadget has two settings ON and OFF.
    When ON is selected A64 will force the changes in the screen to
    drawn at the nearest 8 scan lines and when OFF is selected this
    feature will be disabled.

    It is really difficult to explain the ROUND SCAN LNS GADGET
    without getting overly technical.  Simply, if you are running a
    C64 program and parts of the screen do not look correct try
    turning ON the ROUND SCAN LNS setting to try and correct it.
    The ROUND SCAN LNS GADGET can also cause some program's screens
    to appear totally wrong.  In this case the this option should be
    turned OFF.

OK AND CANCEL GADGETS

    Selecting OK will preserve all changes to the RASTERS settings
    and selecting CANCEL will ignore any changes and abort the
    operation.


SPRITES

    KEY SEQUENCE: None

    This section describes sprites.  Sprites are independent graphic
    images that are not part of the screen in the normal sense.  If
    you are unfamiliar with sprites we recommend reading one of the
    many books available on C64 graphics.

    The C64's sprites and the Amiga's sprites are about as compatible
    as fire and water.  Trying to get Amiga sprites to behave like
    C64 sprites is not an easy feat.  One of the biggest problems
    that you will notice almost immediately is that the sprites will
    flicker.  Because of size differences between Amiga and C64
    sprites there are not enough Amiga sprites to emulate all of the
    C64's sprites at one time.  Because of this Amiga sprites need to
    be re-used, causing the flicker.  The more C64 sprites that are
    used and if they are expanded horizontally the worse the
    flickering gets.  There are also other problems created because


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    of incompatibilities between Amiga sprites and C64 sprites.
    Sprite collisions and sprite priorities are not 100% compatible.
    Most of the problems with emulating C64 sprites are caused by
    restrictions in the Amiga's hardware.  It's hard to believe, but
    there are some things a C64 can do that an Amiga can't.
    compatibility with C64 sprites has been greatly improved since
    earlier versions of A64, but there are still problems that are
    not easily corrected.  Many people have suggested using "BOBs"
    to emulate the C64 sprites, but unfortunately doing this would
    slow A64 down to a crawl.  We will continue to work on sprites,
    but unfortunately there will always be incompatibilities.

    The SPRITES menu option allows you to change how A64 handles C64
    sprites.

    When selecting SPRITES you will be prompted with a requester
    containing several gadgets.  The function of each gadget is as
    follows:

MONO SPRITES GADGET

    The C64 has two types of sprites: multi-colored sprites that use
    4 colors and standard sprites that use 2 colors.  The emulation
    of multicolored sprites can decrease the speed in which A64 runs
    some programs.  The MONO SPRITES GADGET allows you to force A64
    to use standard sprites in place of multi-colored sprites.  This
    will allow A64 to run some programs faster.  This gadget has two
    settings: ON and OFF.  Selecting ON will enable the replacement
    of multi-colored sprites with standard sprites and selecting OFF
    will disable this feature.

SPRITE COL GADGET

    The C64 is capable of generating interrupts when two sprites
    collide with each other.  Because of incompatibilities between
    the Amiga hardware and the C64 hardware these collisions are
    not emulated 100%.  The SPRITE COL GADGET allows you to disable
    sprite to sprite collisions.  This gadget has two settings: ON
    and OFF.  Selecting ON will enable sprite to sprite collisions
    and selecting OFF will disable them.

FRGRD COL GADGET

    The C64 is capable of generating interrupts when a sprite
    collides with part of the normal screen.  Because of
    incompatibilities between the Amiga hardware and the C64
    hardware these collisions are not emulated 100%.  The FRGRD COL
    GADGET allows you to disable sprite to foreground collisions.
    This gadget has two settings: ON and OFF.  Selecting ON will
    enable sprite to foreground collisions and selecting OFF will
    disable them.


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    NOTES: Sprite to foreground collisions are more compatible than
           sprite to background collisions and less problems can be
           expected with this type of collision.

           The SPRITE COL GADGET and FRGRD COL GADGET can be used
           to get endless lives in many C64 games by disabling
           collisions.

PRIORITIES GADGET

    The C64 is capable of displaying sprites either in front of the
    rest of the screen or behind it.  This capability is called
    sprite priorities.  Because of incompatibilities between the
    Amiga hardware and the C64 hardware these priorities are not
    emulated 100%.  The PRIORITIES GADGET allows you to select how
    A64 handles these priorities.  This GADGET has three settings:
    NORM, FRONT and BACK.  Selecting NORM will force A64 to do its
    best to emulate the C64's sprite priorities.  Selecting FRONT
    will force A64 to display all sprites in front of the rest of
    the screen and selecting BACK will force A64 to display all
    sprites behind the rest of the screen.

DATA RATE GADGET

     The DATA RATE GADGET allows you to change the rate in which
     A64 updates the C64 sprite images.  This gadget is a string
     gadget and it allows you to enter a five digit number that
     corresponds to the rate in which A64 updates the C64 sprite
     images. This number can range from 1-65535 and the way A64
     interprets it is as follows:

     A64 uses the DATA RATE value as a countdown to update the C64
     sprite images.  A64 subtracts 1 from this value 60 times per
     second and when the value counts down to 0 A64 resets the
     counter and updates the sprite images.

     For example if you set this setting to 1 then A64 would subtract
     1 from it 60 times per second (1-1=0) and would result in A64
     updating the sprite images 60 times per second.

     See: REFRESH RATE TABLE in the GRAFIX section.

HARDWARE RATE GADGET

     The HARDWARE RATE GADGET allows you to change the rate in which
     A64 updates the Amiga sprite hardware used to emulate the C64
     sprites.  This includes such things as sprite colors, sprite
     positions and sprite re-use (what causes the flickering of
     sprites).  This gadget is a string gadget and it allows you to
     enter a five digit number that corresponds to the rate in which
     A64 updates the Amiga sprite hardware. This number can range


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     from 1-65535 and the way A64 interprets it is as follows:

     A64 uses the HARDWARE RATE value as a countdown to update the
     Amiga sprite hardware.  A64 subtracts 1 from this value 60 times
     per second and when the value counts down to 0 A64 resets the
     counter and updates the Amiga sprite hardware.

     For example if you set this setting to 1 then A64 would subtract
     1 from it 60 times per second (1-1=0) and would result in A64
     updating the Amiga sprite hardware 60 times per second.

     See: REFRESH RATE TABLE in the GRAFIX section.

OK AND CANCEL GADGETS

    Selecting OK will preserve all changes to the SPRITES settings
    and selecting CANCEL will ignore any changes and abort the
    operation.

    NOTE: All the SPRITES settings can have dramatic effects on C64
          programs utilizing sprites.  By changing these settings you
          can dramatically change the speed, appearance and
          useability of many C64 programs, especially games.

          When you bring up A64 Prefs you may notice some images
          disappear from the C64 screen, this is normal.  These
          images are C64 sprites.  A64 Prefs does not support C64
          sprites so they will disappear from the screen when it is
          entered.


ALL GFX

    KEY SEQUENCE: None

    The most time consuming part of A64 is the emulation of C64
    graphics.  The ALL GFX menu option allows you to turn off all of
    A64's graphics allowing A64 to run at much greater speeds.  This
    option can be useful to temporarily disable all graphics allowing
    a C64 program to perform some operation much faster than it
    normally would.  For example if the program you're running does
    extensive calculations or if you want to listen to a program's
    sound at the fastest possible speed.

    The ALL GFX menu option has two settings: ON and OFF.  You can
    select one or the other of these settings and selecting one
    automatically unselects the other.  The current selected setting
    is shown by displaying a checkmark next to it.

    Selecting ON will enable all of A64's graphics.



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    Selecting OFF will stop A64 from updating any C64 graphics.

    NOTES: If you turn off all of A64's graphics don't forget that
           you did or it will appear that A64 has locked up because
           the screen will not change, even when you reset A64.

           This option is not saved as a configuration setting.


REFRESH RATE TABLE

    Listed below is a table of refresh values and their corresponding
    rates that can be used to set the SCREEN REFRESH RATE, SPRITE
    DATA RATE and SPRITE HARDWARE RATE settings.  Your are not
    limited to the values in this table, but they can be used for
    reference.

    REFRESH RATE VALUE         REFRESH RATE
    ------------------       ----------------
            1                60 x per second
            2                30 x per second
            3                20 x per second
            4                15 x per second
            5                12 x per second
            6                10 x per second
           10                 6 x per second
           15                 4 x per second
           30                 2 x per second
           60                 1 x per second
          120                 1 x per 2 seconds
          600                 1 x per 10 seconds
         6000                 1 x per 100 seconds (1.66 minutes)
        65535                 1 x per 1092.25 seconds (18.20 minutes)

    See: SCREEN REFRESH RATE GADGET, DATA RATE GADGET and HARDWARE
         RATE GADGET in the GRAFIX section.

















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