Basic Plus 64 is a self-booting program that can be loaded and run as you would any other Basic program. It loads into the RAM at memory location 38613 ($96D5), then deletes the boot file from memory. At this point it displays the message "Basic Plus enabled" on your screen.
Basic Plus 64 is designed to preserve the memory vectors that it changes, so it can be used in conjunction with other machine language utilities. The only precautions to follow is to load Basic Plus 64 last, and any other utilites in memory must not occupy the RAM from 38613-40959, or the 4K block of RAM that starts at 49152.
Basic Plus 64 adds Direct mode commands to Basic. The added commands are REN, KEYX, HELP and QUIT.
REN renumbers a Basic program. The formats allowed for this command are:
REN
REN,start
REN,start,increment
The defaults for this command are start with line number 100, in increments of 10. If the starting line number is entered, it cancels the default value. If the starting line number and increment number are entered, both defaults are overridden. Here are some examples:
REN: The program is renumbered starting with line number 100, and an increment of 10.
REN,200: Renumbering starts with line number 200, using the default increment of 10.
REN,200,5: Renumbering begins with line number 200, using an increment of 5.
While the renumbering process is occurring, new line numbers representing the arguments to GOTO, GOSUB, THEN, LIST and RUN are displayed on the screen.
KEYX is the next Basic Plus 64 command. It allows you to program commands into the Function keys. There are defaults function key commands:
F1: REN,100,10
F2: REN,10,10
F3: OPEN15,8,15,"I0
F4: LIST
F5: SAVE
F6: LOAD
F7: PRINT
F8: QUIT
You can customize these to accomodate your needs by entering KEYX,"command". The x represents the key number (1 through 8) that you want to use. The command and the quotation marks cannot exceed 16 characters, otherwise you will get a "syntax error" message. The closing quote is optional.
You can enter a maximum of 15 characters, and only if you use the leading quote and do not enter a closing quote. If you need a quotation mark in the text, you must use an apostrophe, or it will be read as the end of text.
Examples:
KEY1,"data"
KEY3,"data100,100,100
KEY5,"load'filename',8"
Note that in the example, KEY3 has 15 characters of text, the maximum allowed. KEY5 shows an example of embedding a quote in the text. When KEY5 is pressed, it displays LOAD"FILENAME".
Entering the HELP command displays the Basic Plus 64 commands.
The QUIT command will exit Basic Plus 64, and restore the vectors as they were when Basic Plus 64 was started. Upon entering the command, it displays the message 'Basic Plus disabled.' on your screen.
Basic Plus 64 also alters the function of the CTRL key. While Basic Plus 64 is active, holding down the CTRL key will stop a listing from scrolling on the screen. It will not start again until the CTRL key is released.
Error Messages
The error messages that can be issued by Basic Plus 64 are as follows:
NEW NUMBERS TOO HIGH : RENUMBER ABORTED. This message appears if the line numbers exceed 63999, the highest line number allowed by Basic 2.0.
RAM OVERFLOW : RENUMBER ABORTED. You'll see this message if there are too many line numbers that fill RAM. The line number table is in the 4K free ram at 49152-53248 ($C000-$CFFF).
X RENUMBER ERRORS. In this example, X is the number of arguments to GOTO, GOSUB, THEN, LIST and RUN that do not represent valid line numbers. They are automatically replaced with the number 63999 by Basic Plus 64.
