Utility 1 - UDG Editor and Font Editor  28-MAR-1998  Geoff Wearmouth.
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    This is the first in a series of screen-resident utilities for the
    ZX Spectrum range and emulators. These programs are different because
    the loading screen is the program. They are called using INPUT USR
    16384. All three are self-deleting and have to be reloaded every
    time they are required.

    The file is saved to a tapfile with a demo basic program that explains
    most features and contains some imperfect characters and udg's to
    experiment with.
    All you really need is the SCREEN$. Resave it to your tools tapfile
    or microdrive. A snapshot is no good but a .scr file can be handy.

    The advantage of screen-resident utilities is that they are easy to load,
    easy to delete and can be used regardless of the size of your program
    and without altering RAMTOP.

    I developed 'u1' so that I could work directly with characters in
    my programs without merging in a Basic editor ar leaving room above
    RAMTOP for a machine-code one. My first attempt was 255 bytes long
    and lived in the printer buffer.

The Program
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    The program can best be examined by using it against one of your
    own programs. In the example program the font can be found by using
    the left arrow in the Character Set Menu. This will scan down
    through memory and any graphics stored as successive bytes will
    reveal themselves.
    On the 16K Spectrum, the top 32K of memory is ignored.
    On the 128K Spectrum there are 19 UDG's instead of the 21 of the
    48K Spectrum.
    There is no facility to save characters from within the program.
    The idea is that you resave your entire program after modifying
    the characters.
    The address of the start of the character set is given on the
    respective Help page available from the Menu and the length is just
    the number of characters multiplied by eight.

History
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Mar 89      v1.1 published on Outlet magazine, Issue19.

Mar 98      bar changed from green to cyan.
            Basic demo written.
            Obsolete Outlet address removed from help screens.
            v1.2 uploaded to ftp incoming directories.

Limitations and Features
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    The program uses only Screen memory and the system
    variables associated with the screen. Apart from resetting CHARS
    to normal and CAPS LOCK off, the program does not affect your
    Spectrum in any other way apart from altering the characters
    of course.

    The program uses ROM routines so is unlikely to work on standard TS2068.

    Send bugs to gwearmouth@hotmail.com