Credit Scroll For The 64

Kenny Lawson

Give your home VCR movies a professional touch with this program for Commodore 64 and VCR owners. With it, your movies can display a scrolling screen of credits that you create and design.

Many people enjoy making home movies with a video camera and showing them to their friends and family on their VCR. With "Credit Scroll," you can add professional-looking scrolling credits to any home movie. Credit Scroll lets you enter lines of text, keyboard graphics, center text, and create scrolls up to 2000 lines long.

Getting Started

Credit Scroll is written entirely in BASIC. Type it in and save a copy to disk. Before you can use the program with your VCR, however, you need to make some connections.

Connecting your 64 to a VCR is easy. The only additional piece of hardware you'll need is a Y-connector with three RCA plugs—two female going to one male. Using Commodore's standard three-jack video cable, plug the chroma and luma (or video) connectors from the monitor end of the cable into the female ends of the Y-connector. Next, plug the video cable's remaining male plug into the VCR's audio dubbing jack, and plug the Y-connector's male plug into the video dubbing jack. These jacks will usually be on the front panel of your VCR, though some VCRs may have them on the rear. Now the VCR is ready to tape the output from your 64.

You should be able to see your computer's screen output on the TV connected to your VCR. If you can't, it's possible to create your credits with your computer connected to your usual monitor and then connect it to the VCR to record the credits (explained below). You'll have to experiment to find the solution that works best with your equipment.

Roll The Credits

Now, simply load Credit Scroll and type RUN. The screen prompts will explain how the program works. All you need to do is enter a line of less than 40 characters. If you enter more than 40 characters, the program reminds you. To enter blank lines, just press RETURN at the prompt.

After you've entered all of your text, type END at the prompt and press RETURN. The screen will tell you to press any key, and you'll have about three seconds before the actual scrolling begins. Before you press the key to start the scrolling, be sure your VCR is set up to record and is properly connected to your 64.

Program Notes

The machine language portion of Credit Scroll—contained in the DATA statements—uses the 64's vertical fine-scrolling register at location 53265 to move the lines of text upward vertically by one row of pixels at a time. Once the register is at the minimum value, the program uses a variation of the technique called double buffering—relocating the active screen memory while the scrolling register is reset—to give flicker-free text movement.

If you want to create scrolls longer than the current limit of 2000 lines, you can make one small adjustment to the program: Simply increase the number in the DIM statement in line 60 to the number of lines you'd like to be able to use.

Credit Scroll

For instructions on entering this program, please refer to "COMPUTE!'s Guide to Typing In Programs" elsewhere in this issue.