Chapter 7
Using 48 BASIC

Subjects covered...

	Using the +3 as a 48K Spectrum
	Entering 48 BASIC mode
	The keyboard under 48 BASIC
	Program entry
	Editing the current line

The +3 has the ability to act exactly like a 48K Spectrum (or Spectrum
+). This achieved by selecting the option 48 BASIC from the opening
menu. In 48 BASIC mode, many of the enhanced features of the +3 (such
as the disk drive, extra memory, full screen editor, multi-channel
sound, RS232/MIDI/AUX interfaces and RAMdisk) cannot be used. The
JOYSTICK 1 and JOYSTICK 2 sockets will still operate, however.

The 48 BASIC mode is included for compatibility reasons only - there
is no advantage in using 48 BASIC (instead of +3 BASIC mode) to write
programs, and it is not recommended. The following information is
included for reference only, or for anybody who is used to the old 48K
Spectrum and wants to use the machine immediately without having to
learn about the +3 BASIC editor.

There are, in fact, two methods of entering the 48 BASIC mode: the
first is by selecting the 48 BASIC option from the opening menu (if
you don't know how to select a menu option, refer back to chapter 2).
When 48 BASIC starts up, you will see the following on the screen...

    +-------------------------------------------------------------+
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    |                                                             |
    | (C) 1982 Amstrad                                            |
    +-------------------------------------------------------------+

The second method allows you to enter the 48 BASIC mode while editing
a +3 BASIC program. To do this (while in +3 BASIC mode), type...

	spectrum

...and press ENTER. The +3 will respond with an OK message [not on any
+3 I've ever used...] and will have changed to 48 BASIC mode,
retaining any program that you had in memory. Once in 48 BASIC mode,
there is no way back to +3 BASIC mode apart from resetting the +3 (or
switching off, then on again).

One major difference between 48 BASIC and +3 BASIC is in the entering
and editing of programs. (Note also that in +3 BASIC the tokens
SPECTRUM and PLAY have replaced the user defined graphics characters
for the keys T and U under 48 BASIC (values 163 and 164).)

Once in 48 BASIC mode, the keyboard performs as follows:

All the BASIC commands, functions and operators are available directly
from the keyboard rather than needing to be spelled out. In order to
accommodate all these functions and commands, some keys have five or
more distinct meanings, obtained partly by 'shifting' the keys (i.e.
pressing either CAPS SHIFT or SYMB SHIFT together with the required
key); and partly by having the machine in different modes. The
flashing cursor contains a letter (K, L, C, E or G) to indicate which
mode you are operating in.

K (for Keywords) mode automatically replaces L (for Letters mode when
the machine is expecting a command or program line (rather than input
data), and from its position on the line the +3 knows that it should
expect either a line number or a keyword. K mode occurs at the
beginning of a line, or after a colon ':' (except in a string), or
after the keyword THEN. Whenever the K cursor appears, the next key
pressed will be interpreted as either a keyword or a line number, as
follows...

+-----------------------------------------------------------------------------+
|TRUE |INV. |     |     |     |     |     |     |     |     |     |     |     |
|VIDEO|VIDEO|    1|    2|    3|    4|    5|    6|    7|    8|    9|    0|SPACE|
|-----------------------------------------------------------------------------|
|       |     |PLOT |DRAW |REM  |RUN  |RAND.|RETRN|IF   |INPUT|POKE |PRINT|   |
| DELETE|     |    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
|-------------------------------------------------------------------------+   |
|         |     |NEW  |SAVE |DIM  |FOR  |GOTO |GOSUB|LOAD |LIST |LET  |       |
|         | EDIT|    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
|-----------------------------------------------------------------------------|
|            |     |COPY |CLEAR|CONT.|CLS  |BORDR|NEXT |PAUSE|     |          |
|            |     |    Z|    X|    C|    V|    B|    N|    M|    .|          |
|-----------------------------------------------------------------------------|
|     |     |     | /-- | --\ |                       | ||  | /\  |     |     |
|     |    ;|    "| \-- | --/ |                 SPACE | \/  | ||  |    ,|     |
+-----------------------------------------------------------------------------+

                            The keyboard in K mode


L (for Letters) mode normally occurs at all times (other than K mode,
described above). Whenever the L cursor appears, the next key pressed
will be interpreted as per the legends on the key-tops themselves,
i.e....

+-----------------------------------------------------------------------------+
|TRUE |INV. |     |     |     |     |     |     |     |     |     |     |     |
|VIDEO|VIDEO|    1|    2|    3|    4|    5|    6|    7|    8|    9|    0|SPACE|
|-----------------------------------------------------------------------------|
|       |     |     |     |     |     |     |     |     |     |     |     |   |
| DELETE|GRAPH|    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
|-------------------------------------------------------------------------+   |
| EXTEND  |     |     |     |     |     |     |     |     |     |     |       |
|  MODE   | EDIT|    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
|-----------------------------------------------------------------------------|
|            |CAPS |     |     |     |     |     |     |     |     |          |
| CAPS SHIFT | LOCK|    Z|    X|    C|    V|    B|    N|    M|    .|CAPS SHIFT|
|-----------------------------------------------------------------------------|
|SYMB |     |     | /-- | --\ |                       | ||  | /\  |     |SYMB |
|SHIFT|    ;|    "| \-- | --/ |                 SPACE | \/  | ||  |    ,|SHIFT|
+-----------------------------------------------------------------------------+

                            The keyboard in L mode


In both K and L modes, pressing SYMB SHIFT together with a key will be
interpreted as follows...

+-----------------------------------------------------------------------------+
|     |     | !   | @   | #   | $   | %   | &   | '   | (   | )   | _   |     |
|     |     |    1|    2|    3|    4|    5|    6|    7|    8|    9|    0|     |
|-----------------------------------------------------------------------------|
|       |     | <=  | <>  | >=  | <   | >   |AND  |OR   |AT   | ;   | "   |   |
|       |     |    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
|-------------------------------------------------------------------------+   |
|         |     |STOP |NOT  |STEP |TO   |THEN | ^   | -   | +   | =   |       |
|         |     |    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
|-----------------------------------------------------------------------------|
|            |     | :   |pound| ?   | /   | *   | ,   | .   | .   |          |
|            |     |    Z|signX|    C|    V|    B|    N|    M|    .|          |
=======-----------------------------------------------------------------=======
=SYMB== ;   | "   | /-- | --\ |                       | ||  | /\  | ,   =SYMB==
=SHIFT=    ;|    "| \-- | --/ |                 SPACE | \/  | ||  |    ,=SHIFT=
=======-----------------------------------------------------------------=======

                The keyboard using SYMB SHIFT in K or L mode


Using CAPS SHIFT in L mode simply converts small letters to capitals.
In K mode, however, CAPS SHIFT does not affect the keywords.

C (for Capitals) mode is a variant of L mode whereby all letters
appear as capitals. The CAPS LOCK key is used to change from L mode to
C mode, and back again.

E (for Extended) mode is used to obtain further characters, mostly
tokens. It is entered by pressing the EXTEND MODE key, and lasts for
only one character (or key depression) thereafter. Whenever the E
cursor appears, the next key pressed will be interpreted as follows...


             <--------- all number keys change PAPER colour ----------->

+-----------------------------------------------------------------------------+
|     |     |blue |red  |mgnta|green|cyan |yellw|white|brght|brght|black|     |
|     |     |    1|    2|    3|    4|    5|    6|    7|off 8|on  9|    0|SPACE|
|-----------------------------------------------------------------------------|
|       |     |SIN  |COS  |TAN  |INT  |RND  |STR$ |CHR$ |CODE |PEEK |TAB  |   |
|       |     |    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
===========---------------------------------------------------------------+   |
= EXTEND ==     |READ |RESTR|DATA |SGN  |ABS  |SQR  |VAL  |LEN  |USR  |       |
== MODE ===     |    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
===========-------------------------------------------------------------------|
|            |     |LN   |EXP  |LPRNT|LLIST|RUN  |INKY$|PI   |     |          |
|            |     |    Z|    X|    C|    V|    B|    N|    M|     |          |
|-----------------------------------------------------------------------------|
|     |     |     |     |     |                       |     |     |     |     |
|     |     |     |     |     |                 SPACE |     |     |     |     |
+-----------------------------------------------------------------------------+

                              The keyboard in E mode


Applying CAPS SHIFT while in E mode, the next key pressed will be
interpreted as follows...


             <--------- all number keys change INK colour ------------->

+-----------------------------------------------------------------------------+
|     |     |blue |red  |mgnta|green|cyan |yellw|white|flash|flash|black|     |
|     |     |    1|    2|    3|    4|    5|    6|    7|off 8|on  9|    0|SPACE|
|-----------------------------------------------------------------------------|
|       |     |ASN  |ACS  |ATN  |VERFY|MERGE| [   | ]   |IN   |OUT  |(C)  |   |
|       |     |    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
===========---------------------------------------------------------------+   |
= EXTEND ==     | ~   | |   | \   | {   | }   |CIRCL|VAL$ |SCRN$|ATTR |       |
== MODE ===     |    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
==============-----------------------------------------------------============
==============     |BEEP |INK  |PAPER|FLASH|BRGHT|OVER |INVRS|     ============
= CAPS SHIFT =     |    Z|    X|    C|    V|    B|    N|    M|     =CAPS SHIFT=
==============-----------------------------------------------------============
|     |     |     |     |     |                       |     |     |     |     |
|     |     |     |     |     |                 SPACE |     |     |     |     |
+-----------------------------------------------------------------------------+

                    The keyboard using CAPS SHIFT in E mode


Applying SYMB SHIFT while in E mode, the next key pressed will be
interpreted as follows...

+-----------------------------------------------------------------------------+
|     |     |DEFFN|FN   |LINE |OPEN#|CLOS#|MOVE |ERASE|POINT|CAT  |FORMT|     |
|     |     |    1|    2|    3|    4|    5|    6|    7|    8|    9|    0|SPACE|
|-----------------------------------------------------------------------------|
|       |     |ASN  |ACS  |ATN  |VERFY|MERGE| [   | ]   |IN   |OUT  |(C)  |   |
|       |     |    Q|    W|    E|    R|    T|    Y|    U|    I|    O|    P|   |
===========---------------------------------------------------------------+   |
= EXTEND ==     | ~   | |   | \   | {   | }   |CIRCL|VAL$ |SCRN$|ATTR |       |
== MODE ===     |    A|    S|    D|    F|    G|    H|    J|    K|    L| ENTER |
===========-------------------------------------------------------------------|
|            |     |BEEP |INK  |PAPER|FLASH|BRGHT|OVER |INVRS|     |          |
|            |     |    Z|    X|    C|    V|    B|    N|    M|     |          |
=======-----------------------------------------------------------------=======
=SYMB==     |     |     |     |                       |     |     |     =SYMB==
=SHIFT=     |     |     |     |                 SPACE |     |     |     =SHIFT=
=======-----------------------------------------------------------------=======

                    The keyboard using SYMB SHIFT in E mode


G (for Graphics) mode occurs when GRAPH is pressed, and lasts until it
is pressed again (or 9 is pressed on its own). A number key will give
a mosaic graphics, and each of the letter keys (apart from V, W, X, Y
and Z) will give a user-defined graphics which, until it is defined,
will look identical to a capital letter. Whenever the G cursor
appears, the next key pressed will be interpreted as follows...

+-----------------------------------------------------------------------------+
|     |     |..## |##.. |#### |.... |..## |##.. |#### |.... |graph|     |     |
|     |     |....1|....2|....3|..##4|..##5|..##6|..##7|....8|off 9|     |SPACE|
|-----------------------------------------------------------------------------|
|       |     | Q   |     | E   | R   | T   |     | U   | I   | O   | P   |   |
| DELETE|GRAPH|     |     |     |     |     |     |     |     |     |     |   |
|-------------------------------------------------------------------------+   |
|         |     | A   | S   | D   | F   | G   | H   | J   | K   | L   |       |
|         |     |     |     |     |     |     |     |     |     |     |       |
|-----------------------------------------------------------------------------|
|            |     |     |     | C   |     | B   | N   | M   |     |          |
|            |     |     |     |     |     |     |     |     |     |          |
|-----------------------------------------------------------------------------|
|     |     |     |     |     |                       |     |     |     |     |
|     |     |     |     |     |                 SPACE |     |     |     |     |
+-----------------------------------------------------------------------------+

                             The keyboard in G mode


Applying CAPS SHIFT while in G mode inverts the mosaic graphics (i.e.
the ink colour becomes the paper colour, and the paper becomes the ink
colour). Hence, the next key pressed will be interpreted as follows...

+-----------------------------------------------------------------------------+
|     |     |##.. |..## |.... |#### |##.. |..## |.... |#### |graph|     |     |
|     |     |####1|####2|####3|##..4|##..5|##..6|##..7|####8|off 9|     |SPACE|
|-----------------------------------------------------------------------------|
|       |     | Q   |     | E   | R   | T   |     | U   | I   | O   | P   |   |
| DELETE|GRAPH|     |     |     |     |     |     |     |     |     |     |   |
|-------------------------------------------------------------------------+   |
|         |     | A   | S   | D   | F   | G   | H   | J   | K   | L   |       |
|         |     |     |     |     |     |     |     |     |     |     |       |
==============-----------------------------------------------------============
==============     |     |     | C   |     | B   | N   | M   |     ============
==CAPS SHIFT==     |     |     |     |     |     |     |     |     =CAPS SHIFT=
==============-----------------------------------------------------============
|     |     |     |     |     |                       |     |     |     |     |
|     |     |     |     |     |                 SPACE |     |     |     |     |
+-----------------------------------------------------------------------------+

                    The keyboard using CAPS SHIFT in G mode


General keyboard notes

If any key is held down for more than 2 or 3 seconds, it will start
repeating. Keyboard input appears in the bottom half of the screen as
it is typed, each character (single symbol or compound token) being
inserted just before the cursor. The cursor can be moved left and
right using the cursor control keys left and right (to the left of the
space bar). The character to the left of the cursor can be removed
using DELETE.

When ENTER is pressed, the line is either executed, entered into the
program, or used as input data. If the line contains a syntax error,
however, a flashing question mark '?' appears next to the error.

As program lines are entered, a listing is displayed in the top half
of the screen. The last line entered is called the current line and is
indicated by the symbol '>' after the line number. Any line in the
program may be selected as the current line (for editing purposes) by
using the up and down cursor keys (to the right of the space bar). To
then edit the select current line, press the EDIT key. (Editing takes
place at the bottom of the screen.)

When a command is executed or a program is run, output is displayed in
th top half of the screen and remains there until either ENTER or the
cursor up or down key is pressed. At the bottom of the screen appears
a report giving a code (digit or letter) referred to in part 29 of
chapter 8. This report remains on the screen until a key is pressed
and the +3 returns to K mode.