Utility 3
---------

        A screen-resident Z80 disassembler (2K of code).
        Will disassemble any 48K Program and all 5 Sinclair/Amstrad
        Roms.
        It has been tested with other ROMS and should work on
        a TS2068 and Sam.
        Contains DISZ80 a routine written by John Kerr, in less than 1K,
        which was published in Subset (Personal Computing World) 1987.
        The other kilobyte consists of a character set, printing/scrolling
        routines, a keyboard reader and ROM paging routines.
        This shell begins at #5000.
        DISZ80 begins at #5100.
        (originally published at #0100 for Amstrad CPC128 CP/M).
        Note. all addresses #5000 higher than originally published.
        David Barrow, Subset's editor, was able to trim another two bytes
        from John's code but they are not implemented here.

Instructions
------------

        On 16/48K machines use LOAD "u3" SCREEN$
        and then without scrolling the display type  PRINT USR 16384.

        On 128K machines select 'Screen' option from edit menu.
        On a Sinclair 128K machine, Roms 1 and 2 appear the same as 3 and 0.
        On a Plus3 all four Roms can be selected.

        Rom 4, Sinclair Shadow Rom, cannot be selected unless it is
        first initialised. Use CLS # before loading.

        On emulators always use CLS before loading, so that the cursor is
        at the bottom of the screen.

        To use enter
        INPUT USR 16384
        This maintains the cursor at the bottom of the screen
        should you wish to reload it.

        The program has to be re-loaded every time it is used ie.
        it self-destructs.

        The file has been saved as a .scr file instead of a snap as you
        probably have something worth disassembling above screen memory.
        This also ensures in can be loaded into Timex emulators.

        This program only writes to screen memory apart from the normal
        use of the machine stack.

        Geoff Wearmouth, Jan 1997
        geoff@wearall.demon.co.uk

Acknowledgements
----------------

John Kerr for sharing his routine DISZ80 with us.
David Barrow (SUBSET Editor) for selecting it for publication.
Personal Computer World for publishing the routine.