This is the program for the twelfth RetroBattlestations BASIC challenge.
This is a silly little program that lets you "make a face". The concept is to simulate a toy which uses small blocks with different patterns on them to let you create a face. The program doesn't use any pixel based graphics, but can take advantage of character based graphics such as those found on Commodore and Atari machines. It could probably be ported to teleprinter type machines, however to make it more interactive it currently uses cursor positioning.
For more details about the challenge, check out the post here:
When working with unfamiliar computers it's often difficult to figure out how to type in characters outside of the normal ASCII printable characters. Odd non-ASCII characters are also challenging to make understandable or store in files on newer computers. Because of this the choice was made to use a funky "base 64" encoding for the tiles. The first letter is the base character in the standard uppercase only 64 character range (32-95), and the second character is the number of times to add 64 to the ASCII character, allowing for encoding of up to 256 characters in two reasonably easy to type characters. For the second character I felt that it would be better for "A" to represent zero rather than the space character, so numbering starts from "A" and wraps around to "@" as the highest value.
The color information is also encoded into the second byte by multiplying the color value by 4, allowing use of all 6 bits.
I have included a tile editor as part of the program, but it is not necessary to type it in if you do not plan to try to design your own tiles. I felt that an editor would be useful for those who want to try to port the program to a new platform, since it would allow viewing of, and experimenting with, the crazy encoding method used by tiles in the DATA statements.
Before you start working on porting the program and changing things to work on your machine, try running the Commodore 64 version in an emulator (or real hardware if you are so inclined) so you can see how the program works and what it does. The advantage of testing in an emulator is that many emulators will allow you to easily paste text as if it were keyboard input so you don't need to hassle with manually typing it in or figure out how to convert the listing to a tape or disk image.
See List of Computers With On-Board BASIC
- Define a custom character set
- Add a way to rotate blocks
- Add a way to save and load faces
- Use shapes on Apple II instead of text
- Make it run faster without resorting to assembly or unreadable code
- A way to print to hardcopy
When typing the program in you can leave off any lines which begin with REM, they are not needed for the program to run. On many platforms you can leave out the whitespace between keywords and operators. IBM BASIC is not one of those however.
Note: On the TRS-80 Color Computer and BBC Micro you need to include the spaces around any IF, AND, OR, or THEN statement.
If you make a mistake and don't want to retype the entire line, most of the BASICs have a way to make corrections.
On Amstrad CPC, use AUTO to start typing commands. Use the arrow keys to move about the line. Exit the AUTO mode py pressing Escape. You can also start on a specific line by entering AUTO 100 (for line 100).
To go to the start or the end of the line use CONTROL+Arrow keys. You can also use SHIFT+Arrow keys to use the copy cursor. This is a second cursor that you move independendly, and will copy whatever is under it to the main cursor when you press COPY.
On an Apple II+ use LIST to print the line with an error, then use ESC followed by A/B/C/D to move the cursor one step at a time. Position the cursor at the beginning of the line, then use the right arrow to move over the line and fix the error. Be sure to arrow all the way to the end of the entire line before you hit RETURN!
On an enhanced Apple IIe, Apple IIc, or Apple IIgs you can also use ESC with the arrow keys. In 80 column mode (enter with PR#3) the cursor will change to a white block with a + in it, push ESC to drop out of movement mode.
Use LIST to print the line with a mistake, then use the arrow keys to move up to the beginning of the line. Each press of the copy key will type in the character under the cursor. Make any necessary edits by just typing on the keyboard and using copy to avoid retyping everything.
Like the others, use LIST to display the line with problems, then use the arrow keys to move up and make any corrections. By pressing shift-INST you can insert a blank character if you missed something. Unlike the Apple II you don't need to arrow to the end of the line before pushing RETURN.
Type EDIT and it will print the line on the screen and put your cursor at the beginning of the line. Arrow left/right and you can use Insert & Delete to make corrections. Like Commodore BASIC, you don't need to arrow to the end of the line before pushing RETURN.
Type the line number and then arrow up (FCTN+E) and it will enter edit mode with that line loaded. You can move within the line with arrow left (FCTN+S) and arrow right (FCTN+D) and move to the previous or next line with arrow up (FCTN+E) or arrow down (FCTN+X). You can delete the character under the cursor with DEL (FCTN+1) or turn on insert mode to insert extra characters with INS (FCTN+2). You do not need to move to the end of the line before pressing ENTER.
This has to be the best built-in BASIC editor I've seen so far! Just type EDIT and the entire BASIC program will be loaded into the built-in word processor where you can make any changes you want. Press F8 to exit the editor and go back to BASIC.
Having a hard time finding where all the BASIC keywords are hidden? Get Commander le Clef's Secret Encoder Wheel with an alphabetical sorted listing of keywords and the secret keypresses required to enter them.