TARBELL CASSETTE BASIC

Written by Tom Dilatush of REAL TIME MICROSYSTEMS, 2240 Main St.
No. 18, Chula Vista, CA 92011 for Don Tarbell of TARBELL ELECTRONICS,
950 Dovlen Place, Suite B, Carson, CA 90746.

This manual describes TARBELL BASIC in such a way as to be
understood by those having previous experience with other BASIC's.
It is not intended as a tutorial, as there are several good 
BASIC texts (see Appendix K).  Where reasonable it is
upward compatible from ALTAIR* 8800 BASIC release 4.0 8k version.
Items which differ significantly from that version are marked
with an asterisk.  Items enclosed in angles (<item>) are defined
in Appendix B.  Items enclosed in brackets ([item]) are optional.

Keyboard Control Characters:

7F  rubout	deletes the last character entered (except in EDIT mode)
15  control-U	deletes the current line being entered
03  control-C	stops the program from running or a listing operation
09  control-I	tabs 8 spaces to the right
13  control-S	stops the program or printing temporarily until another
		key is pushed
2E  period	when pressed in entry mode at beginning of line,
		creates a label with a number 1 higher than the
		preceding label.

Modes of Operation:

    Direct Mode:
	Most TARBELL BASIC statements may be entered and executed while
	in command level.  This statement may be only one line, but
	may be any length up to the limits of memory.  Statements which
	would modify allocated memory, such as DIM & LET, are not allowed
	in direct mode entries.  Statement names are not allowed.
	Multiple statements per line may be seperated by colons (:).

    Entry Mode:
	This mode is entered by typing "ENTER" or ":", and is
	used for creating lines of program text from the keyboard.
	it is also used for inserting lines.  See ENTER command.

    Edit Mode:
	This mode is entered by typing "EDIT" and a line descriptor.
	It is used for making changes to existing lines without
	having to retype the whole line.  See EDIT command.

    Run Mode:
	This is the normal, programmed mode.  The stored TARBELL
	BASIC program begins executing when a "RUN" command is entered.

To acquire a better feel for the modes of operation, and for using
TARBELL BASIC in general, see the sample run in Appendix F.



* ALTAIR is a trademark/tradename of Pertec Computer Corp.


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