DefChar Spectrum Character Editor
                   =================================
                      J.G.Harston v1.20 1984-2003
            http://mdfs.net/Software/Spectrum/Fonts/Editors
               70 Camm Street, Walkley, Sheffield S6 3TR

Introduction
------------
DefChar is a simple character editing program. The Spectrum has 21 user-
definable graphics characters available to the user. The ordinary characters
can also be defined by altering the system variable CHARS to point into RAM.
DefChar allows you to manipulate the character definitions in various ways.

These instructions describe the Spectrum version of DefChar. The BBC and
Amstrad versions are functionally the same.


                               MAIN MENU
                               =========

On running DefChar the main menu is displayed listing the available main
commands, the complete character set, and a grid displaying the character
being edited. At any point if DefChar stops with an error, it can be rerun
to return directly to the main menu.

A: Change start of characters
-----------------------------
This changes the address in memory of the character set being edited. Valid
values for this are 40000 to 65000. If you enter a value out of this range,
it is ignored. A valid value is rounded down to the nearest multiple of 256.
The character start address is shown on the main menu under the character
set.

R: Reset
--------
This will reset the character set being edited to that of the character set
in the ROM. When selected, you have to confirm by entering 'Y'.

W: SWAP
-------
This swaps two character definitions

E: EDIT
-------
This enters editing mode to define characters.

V: VIEW
-------
This will view a character by drawing it on the large editing grid.

L: Load a file, S: Save a file
------------------------------
This allows you to load and save the full character set. You will be
prompted for the filename, and the character to start to load/save. Pressing
ENTER will start at character 32 (space). When saving you are then prompted
for the final character to save, pressing ENTER will save to the end of the
UDCs, character 164.

D: Drive
--------
This allows you to set the default drive for loading and saving files. Enter
'1' to '8' for microdrives 1 to 8, 'T' for tape or 'S' for serial link. When
the program starts this is set to the drive just loaded from. The current
drive number is displayed on the main menu below the character set.

C: Catalog
----------
This catalogs the current device as selected with D from the main menu. When
cataloging from tape, pressing ENTER will stop the listing.

Q: Quit
-------
This exits the program. You are asked for confirmation, then given a page of
instructions on how to select the character set in memory. After pressing
another key, the program NEWs itself to clear memory.


                          CHARACTER EDITOR
                          ================

Pressing 'E' from the main menu enters the editing menu. This has a similar
layout to the main menu, with the character set at the top, the editing grid
at the left, and the menu of operations at the right.

The cursor keys 5, 6, 7, 8 move the cursor around the editing grid clearing
pixels. Holding Shift down moves around the editing grid setting pixels.

M: MIRROR
---------
This reflects the grid across the vertical axis.

F: FLIP
-------
This reflects the grid across the horizontal axis.

Q: SPIN \
---------
This reflects the grid across the diagonal axis from the top-left corner to
the bottom right corner.

P: SPIN /
---------
This reflects the grid across the diagonal axis from the top-right corner to
the bottom-left corner.

I: INVERT
---------
This inverts every pixel on the grid.

S: SUPERIMPOSE
--------------
This superimposes another character onto the grid. You are asked whether to
use XOR or OR to merge the characters, then the character to be
superimposed. Note that XOR is reversible by doing the same again, but OR
isn't.

Y,G,H,B: SCROLL
---------------
These scroll the grid around in the of the four directions. The keys are
laid out in a diamond shape, pointing in the directions that they scroll in.
Eg Y at the top scrolls upwards, etc.

V: VIEW
-------
This copies a character onto the grid, clearing whatever was there before
it.

ENTER: Enter character
----------------------
This function enters the definition into a character. You are asked for the
character, and pressing <enter> on its own will abort the entry. After
entering, the character set is updated, and you will be able to see the new
character in it.

E: Exit to main menu
--------------------
This will return you to the main menu where you can load and save the
character set, and do other functions.


Entering character codes
========================
In various places you are asked for 'Which character'. In answer to this,
you can enter the character code or the actual character. If the string you
enter is only one character, then that is the character to use, otherwise
the string is evaluated as a number. If you give a number out of range or
you enter invalid characters, you will be asked to enter it again. Just
pressing <enter> will cause the input to be ignored.

Valid characters are 32 to 165 and -1 to -9. The characters '-1' to '-9' are
spare ones that aren't used in  the character set, but they can be used for
temporary storage in more complicated manipulation.


Files and filenames
===================
The Devpac/Tasword "d:filename" file access convention is used. When loading
or saving files, if the second character of the filename is ':', then the
first character specifies what device to use, either 'T' for tape, '1'-'8'
for microdrive 1 to 8 or 'S' for serial link. Otherwise, the default device
is used.

For example, "1:JSWChars" refers to a file "JSWChars" on microdrive 1,
"T:Matrix" refers to a file "Matrix" on tape, "Cyrillic" refers to a file
"Cyrillic" on the default device set by the Drive option.

DefChar will load and save with the Discovery and the DISCiPLE as they use
standard microdrive commands.

When a full character set is saved from CHR$32 (space) to CHR$164 (UDC U),
1024 bytes of data are saved consisting of the 96 main characters CHR$32 to
CHR$127 followed by 72 spare bytes forming the temporary characters '-1' to
'-9', followed by the User Defined Characters 'A' to 'U'.


Using the characters in other programs
======================================
To load a character set with another program, you use:

    LOAD "<filename>" CODE <start>
 or LOAD *"m";<drive>;"<filename>" CODE <start>

where <drive> and <filename> are the file to be loaded and <start> is the
address in memory to load the file. You can then select the character set
with:

    POKE 23606,start-256*INT(start/256):POKE 23607,INT(start/256)-1

The default ROM character set can be selected with:

    POKE 23606,0:POKE 23607,60


Version History
===============
1.20    Jul 1986: Uses d:filename file access
1.11    Jun 1986: FontEditor: Branched version with command entry for MegaBasic
1.11    Mar 1986: DefCharCmd: Branched version with command entry
1.10    Apr 1986: Entered as Computer Studies project with Charmaker
1.10    Oct 1985: Updated for microdrive access
1.00    Feb 1985: First completed version