Commodore Plus 4 - Page 60

48 The BASIC Language
Option 1 inverts the color values, so the shape is drawn as a reversed image of
the saved area.
Option 2 overlays the shape on the existing screen pattern.
Option 3 displays only that part of the shape that covers an existing screen
pattern.
Option 4 inverts the part of the existing screen pattern covered by the shape.
Chapter 4 further explains the GSHAPE and SSHAPE commands.
HEADER Abbr. heA
HEADER disk name, Idisk id, Ddrive, ON Uunit
Before you can store information on a new, blank disk, you must prepare the
disk by formatting it. Formatting, also called headering, puts the blank disk into
the format required by your disk drive. The disk is divided into blocks and a
directory for the disk is prepared. Headering is necessary because blank disks are
manufactured to be used in any brand of disk drive, and you need to format the
disk so that it is compatible with your disk drive.
You MUST header a new disk before you can save files on it, but use the
HEADER command with great care because headering completely and perma
nently erases any files already on the disk. You can header a used disk if you are
willing to erase its current contents.
Parameters: "disk name", lid code, D drive number, U unit number
1. The disk name (in quotes) can be up to 16 characters long.
2. Give the disk a unique two-character code. Use two characters for an id
code, not just one. Type an I before the id code.
3. Drive numbers are either 0 or 1. The order of the id code and drive number
parameters can be reversed.
4. Unit number is an optional parameter. Use it only if you have more than one
disk drive connected to your computer and you are using a device other than unit
8 in the header procedure. You must precede the unit number with U, and the unit
number must be between 8 and 11. You can type ON before U, but ON is not
required.
Are You Sure?
When you issue a HEADER command and press RETURN in immediate mode,
the command is not executed immediately. First, the computer displays the
question ARE YOU SURE? This question gives you a chance to make sure the
disk does not contain information you want to keep.
To proceed with the headering procedure, type Y or YES and press RETURN.
To abort the header, just press RETURN. In program mode, the question is not
asked.