By Tom R. Halfhill — originally published in COMPUTE!’s Gazette Issue 2, August 1983
Each month, COMPUTE!’s Gazette for Commodore will tackle some common questions we are asked by new VIC-20/Commodore 64 owners and by people shopping for their first home computer.
Q. I recently bought a Commodore disk drive. When I try to save programs on some new blank disks I bought, something goes wrong. The red light on the disk drive starts flashing, and the program is not saved. I’ve tried this with several disks, all brand-new, and none of them work. What is happening?
A. As you probably know, a flashing red light on a Commodore disk drive indicates some sort of error condition. There are several things to check for if you have this problem. Some might seem obvious, but check them anyway.
First, if you have a Commodore 64, make sure you are using a VIC-1541 disk drive. The older VIC-1540 drives – which look identical – will not work with the 64 without special adjustments. The 1540 drives are intended for VIC-20s. The newer 1541 drives work with both computers.
Second, check all the plug connections. Be certain the plugs are firmly seated.
Third, make sure the disk drive is level. We’ve found that some Commodore disk drives are sensitive to this.
Fourth, the disk drive should not be too near the TV set or monitor. This goes for Datassette recorders, cassette tapes, and disks, too. TVs and monitors generate strong magnetic fields which can interfere with disk drives and recorders, and which can erase tapes and disks. Try moving the disk drive or Datassette as far away from the TV as its cord allows. Sometimes it helps to move the storage device to the other side of the TV, because some TVs generate a stronger magnetic field on one side than on the other.
Fifth, examine the floppy disk on which you’re trying to save the program. When you’re holding the disk as if inserting it in the drive, you should see a tiny notch cut into the left side of the protective sleeve. This is a write-enable notch. The notch allows data to be recorded on the disk. If the notch is absent, or covered with a piece of tape, the disk is write-protected. This means the disk drive will read the disk and load programs, but will not allow programs to be saved. Commercial software on disk usually is write-protected so you can’t accidentally erase it. New blank disks should have uncovered notches. Never defeat the write-protection on a disk unless you’re sure you know what you’re doing.
The final problem to check for actually happened to someone we know. The disk drive worked fine with the disk that came with it, but would not save programs on some new blank disks – the drive would stop with the red light flashing. After checking everything else, it turned out the new disks were not formatted. Without going into detail here, formatting is basically a way of preparing a new disk so the disk drive can use it. All new disks must be formatted before their first use. Once a disk is formatted, it need never be formatted again – unless you want to reuse it for some other purpose (formatting completely erases a disk). New blank disks are not sold preformatted because different brands of computers use different disk formats, and the formats usually are incompatible.
To learn how to format a new disk, consult page 15 of the VIC-1541 User’s Manual, or pages 17 and 18 of the VIC-1540 User’s Manual.
Q. Why do I have to press the RETURN key each time I type in a command or a line of a BASIC program?
A. To tell the computer to accept and act on what you’ve typed.
When you type something on the keyboard, even though it appears on the screen, the computer is not aware of anything until you press RETURN. Before pressing RETURN; you are free to back up the cursor and make changes to your typing. Pressing RETURN tells the computer to accept the input, and it will respond in one of two ways:
If you do not type a number before the input, the computer will act on the input immediately after you press RETURN. This is called immediate mode or command mode. For example, if you type PRINT “HELLO” and press RETURN, the computer will immediately print the word HELLO on the screen, or anything else you’ve typed between the quotation marks. The computer interprets PRINT as an immediate mode command.
But if you type 10 PRINT “HELLO” and press RETURN, nothing happens immediately. The number 10 (or any number up to 63999) tells the computer that what follows is a line of a program.
The computer then interprets PRINT as a program instruction. It will not execute, or carry out, the instruction until you run the program by typing the command RUN (followed, of course, by a RETURN).