A few months ago, I was asked to judge RUN's writing contest. As a high school English teacher, I thought it would be an excellent opportunity to show students the writing process, so I hauled my C-128 into the classroom, hooked it up to a VCR that fed into a 27-inch monitor, and booted up one of the contest entries that I considered quite good.
Unfortunately, I couldn't use my computer monitor to read the text aloud while the class looked at the big screen, because the big screen hogged the video. I was forced to sit in front of the big screen with my back to the class while a student at the blind computer pressed the next-screen key every time I signaled.
Anyone doing a video presentation wants a private screen so they can face their audience. With the C-128's dual video modes, it was easy to create a machine language routine that let me use two monitors at once. My program, VIC/VDC, copies the VDC (80-column) display to the VIC (40-column composite) display, and vice versa. That way, you can use the computer monitor in VDC mode and the VCR monitor in VIC mode, without buying new cables or messing around with wires.
The two modes, however, have different screen widths--80 columns versus 40 columns. With this program, you can use the VDC's double-pixel mode to make the 80-column screen look like it has only 40.
This routine works by adding commands to the Escape vocabulary as follows:
ESCAPE/TAB: Copy one screen to another.
ESCAPE/_ (back-arrow): Toggle the copy direction (VIC to VDC, or vice versa).
ESCAPE/+ (plus sign): Set 80-column mode to double-width.
One note: You don't need two monitors hooked up to test the program. Just put your computer in SLOW mode (type SLOW and press return) and flip your display button back and forth.
The program resides in memory locations 3072 to 3487, so it isn't compatible with software that uses that area. It runs in Direct mode and can be incorporated into any software you write.
To get started, copy both the machine language file VIC/VDC and the Basic loader VIC/VDC MAIN to a work disk using ReRUN's menu. If you wish to make additional copies of the program, simply run the Basic loader. To use the program, load the machine language file with the command BLOAD "VIC/VDC". Then call it by typing SYS 3328. Anytime you hit run-stop/restore, you'll need to enter the SYS again.
