nanochess / Bootbasic

| | | | | ___ / _ \ / | / __
| | ___ ___ | || |/ / /\ \ --. | | | / \/ | '_ \ / _ \ / _ \| __| ___ \ _ |--. \ | | | |
| |) | () | () | || |/ / | | |/_/ /| || _/
|./ _/ _/ __/_| |/_/ _/ ____/

bootBASIC interpreter in 512 bytes (boot sector or COM file) by Oscar Toledo G. Jul/22/2019

http://nanochess.org https://github.com/nanochess

This is an integer BASIC language interpreter.

It's compatible with the 8088 processor (the original IBM PC).

If you want to assemble it, you must download the Netwide Assembler (nasm) from www.nasm.us

Use this command line:

nasm -f bin basic.asm -Dcom_file=1 -o basic.com nasm -f bin basic.asm -Dcom_file=0 -o basic.img

Tested with VirtualBox for Mac OS X running Windows XP running this interpreter, it also works with DosBox and probably with qemu:

qemu-system-x86_64 -fda basic.img

Enjoy it!

| | | |___ ___ _ ( )__ | / |__ _ _ _ _ _ __ | | | || (-</ -) '|/(-< | |/| / | ' \ || / _ | | _///___|| /__/ || |_,|||_,_,||

Line entry is done with keyboard, finish the line with Enter. Only 19 characters per line as maximum.

Backspace can be used, don't be fooled by the fact that screen isn't deleted (it's all right in the buffer).

All statements must be in lowercase.

Line numbers can be 1 to 999.

26 variables are available (a-z)

Numbers (0-65535) can be entered and display as unsigned.

To enter new program lines: 10 print "Hello, world!"

To erase program lines: 10

To test statements directly (interactive syntax): print "Hello, world!"

To erase the current program: new

To run the current program: run

To list the current program: list

To exit to command-line: system

Statements: var=expr Assign expr value to var (a-z)

print expr Print expression value, new line print expr; Print expression value, continue print "hello" Print string, new line print "hello"; Print string, continue

input var Input value into variable (a-z)

goto expr Goto to indicated line in program

if expr1 goto expr2 If expr1 is non-zero then go to line, else go to following line.

Examples of if:

if c-5 goto 20 If c isn't 5, go to line 20

Expressions:

The operators +, -, / and * are available with common precedence rules and signed operation. Integer-only arithmetic.

You can also use parentheses:

 5+6*(10/2)

Variables and numbers can be used in expressions.

The rnd function (without arguments) returns a value between 0 and 255.

Sample program (counting 1 to 10):

10 a=1 20 print a 30 a=a+1 40 if a-11 goto 20

Sample program (Pascal's triangle, each number is the sum of the two over it):

10 input n 20 i=1 30 c=1 40 j=0 50 t=n-i 60 if j-t goto 80 70 goto 110 80 print " "; 90 j=j+1 100 goto 50 110 k=1 120 if k-i-1 goto 140 130 goto 190 140 print c; 150 c=c*(i-k)/k 160 print " "; 170 k=k+1 180 goto 120 190 print 200 i=i+1 210 if i-n-1 goto 30

Sample program of guessing the dice:

10 print "choose "; 20 print "a number "; 30 print "(1-6)" 40 input a 50 b=rnd 60 b=b-b/6*6 70 b=b+1 80 if a-b goto 110 90 print "good" 100 goto 120 110 print "miss" 120 print b

ATTENTION <<

Do you would like more details on the inner workings? This program is fully commented in my new book Programming Boot Sector Games and you'll also find a 8086/8088 crash course!

Now available from Lulu:

Soft-cover http://www.lulu.com/shop/oscar-toledo-gutierrez/programming-boot-sector-games/paperback/product-24188564.html

Hard-cover http://www.lulu.com/shop/oscar-toledo-gutierrez/programming-boot-sector-games/hardcover/product-24188530.html

eBook https://nanochess.org/store.html

These are some of the example programs documented profusely in the book:

• Guess the number.
• Tic-Tac-Toe game.
• Text graphics.
• Mandelbrot set.
• F-Bird game.
• Invaders game.
• Pillman game.
• Toledo Atomchess.
• bootBASIC language.