Vipersoft BASIC Instructions - Transcribed
------------------------------------------
August 5, 2008
By Lance Squire

This information is based on a posting to the Bally Alley discussion group.
This is part one.  Lance does NOT have part 2.


NEW System level commands:

ZERO [ Zero out variables A-Z]

DEFAULT [ Reset system variables,
IE. Character - Grafix windows,
Sound Processor level Etc. ]

NEW [ Erases and checks all
memory, updates size (SZ) to
reflect available program area,
performs the ZERO and DEFAULT
commands ]

NEW Grafix Commands:

CIRCLE X,Y,R,M
SCROLL X,Y,XS,YS,L
SNAP X,Y,XS,YS,P(String No.)
POINT X,Y,M
SHOW X,Y,SM,P(String No.)

Legend:

X  = Horizontal pixel center
Y  = Vertical " "
XS = Horizontal pixel width
YS = Vertical pixel height
M  = Screen write Mode
SM = Show screen write Mode
L= + or - no. of pixel lines

Data Operator

DATA Variable, #, #, #, Etc.

Example: DATA A,1,2,3
Is equivalent to:
A=1,B=2,C=3

New Screen Write Modes
[ BOX, CIRCLE, LINE and POINT ]

0-nothing 4-Plop 0
1-XOR 1 5-Plop 1
2-XOR 2 6-Plop 2
3-XOR 3 7-Plop 3

Lance Notes: 0-3 XOR using colour value 0-3 4-7 'PLOP' using colour
value 0-3

New Show Modes

0-PLOP (Shown pixels only)
1-OR (Shown pixels plus existing
screen image)
2-XOR (Shown pixels change color
when coincidental with
screen image)

New System Variables

XL+XR [ Left+Right Grafix window ]
YT+YB [ Top+Bottom Grafix window ]
CL+CR [Left+right Character window]
CT+CB [Top+Bottom Character window]
CF [ Character Font ]
CC [ Character Color ]
FA [ Foreground Color 1 ]
FB [ Foreground Color 2 ]
FC [ Foreground Color 3 ]
BC [ Background Color ]
LC [ Last Character on screen ]
NB [Print # Base (Bin, Hex, Dec)]

New System Functions

Address Operator <- (Left arrow)
Putting a left arrow in front
of a variable, will yield its'
physical memory address.

Example:
PRINT <-A
Will print:
-32598

Which is the memory location where A's value is stored.

Hex number Operator "!"
Putting a ! in front of a
number, flags it as Hexadecimal.

Example:

PRINT !2FF Yields 767 the
Decimal equivalent.

Byte access Operator "BYTE"
BYTE(Variable, Byte #)

Example: BYTE(A,0)=1;BYTE(A,1)=1;
PRINT A
Yields: 257, The word value
PRINT BYTE(A,1)
Yields: 1, the High byte value

Token Abbreviation

Tokens may be Abbreviated by
typing the first letter or two of
the word followed by a period

Examples:

PRINT = P. (Nothing else starts
with P )
DATA = DA. (DEFAULT also starts
with D )

Viper Keyboard Tokens

Control Token
Character Command
A RND
B BOX
C CLEAR
D DATA
E EDIT
F FOR
G GOSUB
H ERASE
I INPUT
J GOTO
K IF
L LIST
M GO
N NEXT
O CIRCLE
P PRINT
Q SNAP
R RETURN
S STEP
T TO
U POINT
V DEFAULT
W SHOW
X RUN
Y SCROLL
Z ZERO

TAPE FUNCTIONS

300 baud Bally BASIC Compatibility

:PRINT :INPUT :LIST

These 3 commands are implemented in the
same way as in Bally BASIC.

Due to the increased speed of extended
BASIC, NT (Note Time) should be set to 3
when using :PRINT to ensure a good load
using :INPUT in Bally BASIC.

2000 baud Astro BASIC Compatibility

PUT %(variable),number

PUT in Ext. BAS. is compatible with
:PRINT %(variable),number in Astro
BASIC. Here, the variable would be the
beginning address of a block of memory
and number, the word count of the block.
[PUT @(variable),number is also valid]

GET %(variable)

GET in Ext. BAS. is compatible with
:INPUT %(variable) in Astro BASIC.
Here, variable is the beginning
address in memory to be loaded from tape.

LOAD

LOAD in Ext. BAS. is equivalent to
:INPUT %(-24576) in Astro BASIC.

An Ext. BAS. program saved to tape
using the SAVE command, can then be
loaded under Astro BASIC using the
command :INPUT %(-24576).

SAVE

SAVE is equivalent to
A=-24576;:PRINT %(A),(%(20000)-A)/2+RM

Using the sequence above to save an
Astro BASIC program will allow you
to input it under Ext. BAS. with LOAD

VERIFY

VERIFY is equivalent to :LIST in Astro
BASIC. It functions the same, returning
a ? if it detects an error.  V. is all
that is necessary to verify a tape made
with SAVE or PUT.


End of Part 1