Sarah Keates' character editor not only allows you to redefine
characters, it automatically writes the subroutines to use the new
character set in your own programs
Many readers will know that it is possible to change
the character set on the Atari in BASIC and almost everybody has
seen a changed character set for it is a technique used in many
commercial games. There have been several character designers
published in the past but most of them save only the DATA for the
revised set of characters and leave the user to devise his or her own
way of using the new character set. Now Font Factory will allow even
those with the minimum of programming knowledge to generate and use
their own characters sets. Font Factory will write the necessary
subroutines for you! All you will need to do is ENTER the subroutine
created into your own program and place an appropriate at the start
of the program. It is even possible for you to load existing
character sets such as those on the PAGE 6 issue disks and save them
for use in your own programs.
The Font Factory is a flexible and powerful character
editor. Fonts can be saved on disk or cassette either directly or in
the form of Basic DATA statements. It can even generate a subroutine
to install your custom sets into your own programs. The Font Factory
runs on any 8-bit Atari with at least 32K of memory and a disk drive
or cassette deck.
GETTING STARTED
Typing in The Font Factory is straightforward if you
use TYPO 3, just type it in and SAVE it to disk or CSAVE to
cassette. RUN the program and when the program has initialised, the
main editing screen will be displayed. In the top part of the screen
is a window showing the entire character set. In the middle of the
screen is a menu of the available editing commands and the editing
grid. On the grid, an enlarged view of the character currently being
edited is displayed. Beneath the grid, the internal and ATASCII
codes for the character are shown.
There is not room here for a full discussion on the
theory of character definition but basically any point plotted in
the
8 x 8 matrix used for each character will be shown as part of the
character and any point not plotted will be shown as blank. If you
do not understand the theory fully, just RUN the program and
experiment by making some changes to a character and then storing
it. You will see the results on screen and will soon get the hang of
it.
________
We are proud to present Font Factory, not only
because it is a good program but because its author, Sarah Keates,
is just 14 years of age. Sarah lives in Belgium. The presentation of
her program and article was one of the most professional we have
ever had and puts many others to shame! Where are the other ladies,
then? And how about some of the young ( and not so young!) lads
seeing if they submit programs equally as good.
EDITING COMMANDS
The commands available are shown on screen at all
times but for reference and greater explanation are as follows.
+ - * = – Moves the cursor around the grid
(there is no need to use CONTROL).
Space Bar – Draws or deletes a point on the
grid.
C – Clears or fills the grid. If the program
is in DRAW mode, then the grid will be filled in, if in delete mode,
the grid will be emptied.
R – Restores the character being edited to the
ROM character.
S – Stores the contents of the grid. The
character set window will be updated to show the new character.
N – Selects a new character to be edited. If
the program is in CHARACTER input mode, type the character you wish
to edit and press RETURN. If the program is in ASCII input mode,
enter the ATASCII code of the character. NB: some characters cannot
be entered in CHARACTER mode, for example Space (ATASCII 32).
< – Selects the preceding character in the set
to be edited. If the program reaches the beginning of the set, it
will wrap around to the end of the set.
> – Selects the next character in the set to
be edited. If the program reaches the end of the set, it will wrap
around to the beginning of the set.
D – Toggles between DRAW and DELETE mode. The
current selection is highlighted on the menu.
A – Toggles between CHARACTER and ATASCII
input mode. The current selection is highlighted on the menu.
E – Exits the program. This command leaves the
user's character set intact.
M – Restores the ROM character set.
Shift I – Displays the SAVE/LOAD menu. The
character being edited should be stored before using this command.
SAVING AND LOADING
As stated, Shift-I will display the sub-menu for
saving or character sets. This has 8 options which are as follows.
Option 1 – Saves the entire character set
to disk or cassette extension '.FNT'.
Option 2 – Saves the entire character set
to disk or cassette as BASIC DATA statements. The file will be in
LISTed format with the extension '.LST'.
Option 3 – Saves all characters which have
been altered directly to disk or cassette with the extension '.FNT'.
Option 4 – Saves all characters which have
been altered as Basic DATA statements with the extension '.LST'.
Option 5 – Loads the entire character set
from disk or cassette.
Option 6 – Loads a partial character set
from disk or cassette.
Option 7 – Lists the directory of drive 1.
Option 8 – Returns to the main editing
screen.
A few notes are useful regarding the options.
Firstly, the Font Factory includes a routine to validate filenames.
It will not allow you to enter filenames that are too long or
contain illegal characters. Font Factory filenames do not need
extensions as these are automatically added by the program. If you
do enter an extension, the program will overwrite it. There are two
ways of entering filenames:
1. Just a filename. The program will add the
default device specifier ("D:") and the correct extension.
2. Device specifier:filename. The program will use
the device specified (if it is valid) and add the correct extension.
Whenever you save a character set, you will be
given the option of generating a subroutine to load the set. If the
set is saved as Basic DATA statements using options 2 or 4, the
loader will be included with the DATA statements, and the program
will have the extension of '.LST'. This may be added to any program
of your own by ENTERing it and then resaving the entire program. If
the set is saved directly to disk or cassette with options 1 or 3,
the set will be saved with the extension '.FNT'. and the loader will
be saved as a separate file in LISTed format with the extension '.LST'.
This subroutine will read the character set from disk or cassette
but the DATA will not form part of your program.
It should be noted that if you have saved a
partial character set only, the loader will only load the characters
which you have altered. The rest of the set will be blank unless you
copy the ROM set first into the appropriate part of RAM.
Font Factory really is very easy to use even with
a limited amount of programming knowledge. Give it a try, you will
be able to give a new look to many of your programs.
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PROGRAM BREAKDOWN
310-360 -
Calls the subroutines to display a character.
370-440 -
Converts the 8 decimal values for a character into a bitmap.
450-540 -
Converts a bitmap to 8 decimal values.
550-640 -
Prints the internal and ATASCII codes for a character.
650-730 -
Prints the character grid.
740-810 -
Converts an ATASCII code into an internal code.
820-860 -
Converts an internal code to an ATASCII code.
870-920 -
Gets the 8 decimal values for a character from memory.
930-1040 -
Copies the ROM character set into RAM.
1050-1170
- Moves the cursor around the grid.
1180-1210 - Enables the display list interrupts.
1220-1390 - Main loop to read the keyboard.
1400-1510 - Selects a new character to be edited.
1520-1640 - Clears the character grid.
1650-1760 - Restores a single character to it's ROM counterpart.
1770-1890
- Stores an edited character.
1900-1940 - Toggles between DRAW and DELETE modes.
1950-2000
- Draws or deletes a point.
2010-2060 - Toggles between ATASCII and CHARACTER input mode.
2070-2130 - Gets the next character in the set.
2140-2200
- Gets the previous character in the set.
2210-2270 - Calls the subroutine to copy the ROM character set.
2280-2610
- Displays the Input Output menu.
2620-2740
- Asks if a loader routine is required.
2750-2900
- Gets a filename and calls the parsing routine.
2910-3170 - Saves a complete character set to disk or cassette.
3180-3420
- Loads a complete character set from disk or cassette.
3430-3780
- Generates a loader subroutine for DATA files.
3790-3870
- Saves DATA for an entire character set.
3880-3980
- Saves DATA for a partial character set.
3990-4180
- Builds a Basic DATA statement.
4190-4430 - Generates a loader subroutine for DATA statements.
4460-4520
- Sets up the line number for a Basic DATA statement.
4530-4830
- Parses a filename.
4840-5080 - Lists the directory for drive 1
5090-5470
- initialises arrays.
5480-5620 - Sets up the machine code for the display list interrupt.
5630-5920
- Sets up the screen display.
5930-6010
- Exits the program.
MAIN VARIABLES
|
CHBASE |
The location of
the RAM copy of the character set. |
| ST |
The location of
the ROM character set |
| PAGE |
The MSB of
CHBASE. This value is
POKEd into the character set pointer at location 756 |
| CHMAP(8,8) |
The bitmap of
the character. |
| CHDEC(8) |
The 8 decimal
values of the character. |
| CHNUM |
The number of
characters altered. |
| CHALT$ |
Used to tell the
specific characters that have been altered. |
| ACD |
The ATASCII code
of the character. |
| ICD |
The internal
code of the character. |
| AFLAG |
Flag to indicate
whether the program is in CHARACTER or ATASCII input mode. |
| DFLAG |
Flag to indicate
whether the program is in DRAW or DELETE mode. |
| LFLAG |
Flags whether a
loader routine is required. |
| KEY |
The code of the
key pressed. |
| ML$ |
The machine code
routine to copy the character set. |
| ML2$ |
The machine
language routine to print the character set to the screen. |
| DLI$ |
The display list
interrupt routine. |
| BD$ |
The Basic DATA
statement. |
| FF$, FL$ |
Filenames and
extensions '.FNT','.LST'. |
| A,B,C,D,E,L,M |
are general
purpose variables. |
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