We've had quite a few calls on Keystroke Artist (ANTIC, Aug. 1983). The program does run as published, but it's a bit difficult to type in. When typing the string assignments in lines 4000 to 4070, use the chart on page 104 of the same issue for guidance on graphics characters.
Lines 4000 and 4030 contain 120 characters each and 4020 contains 122 characters. To enter these lines, you must first execute a POKE 82,0 command in Immediate Mode (without a line number) to allow sufficient space. Omit the space between the line number and the beginning of the line, and in 4020, omit the final quote mark.
Also, some of the characters in lines 4000 to 4070 are ambiguous. The twenty-first character in the second line of line 4000 is an inverse lower case L. The fourth character in the second line of line 4030, also appearing subsequently in the listing, is an inverse underline character (SHIFT] [-]). The ninth character in the same line is an inverse blank, as is the 14th character in the string CAL$ in line 4060. The eighteenth character in the second line of 4030 is a blank, as is the next to the last character of the string MIRROR$ in line 4040.
In line 1060, the inverse message: should read "CHANGE COLOR TO" followed by a semicolon and a colon.
Cassette users may have problems loading a saved picture file. If you have this problem, change the number 128 in lines 1160 and 1690 to a 0 before saving a picture. Files will take twice as much tape, but loads will be more reliable.
The article "Up and Down - Vertical Movement for Player/Missiles" is excellent. However, nowhere does the article mention how to load data for missiles. Please help!
San Jose, CA
All four missiles are set by the program to be two bits wide by one bit high when enabled. Unfortunately, this cannot be altered. -ANTIC ED
TALK IS CHEAP
There is an error in Figure 2: Diagram of voice-input circuit (ANTIC, p. 65, July 1983). The bottommost connection in the diagram should be labeled POT A (PIN 9), not GROUND (PIN 9).
In your June 1983 issue of ANTIC, was an article entitled "Dancin' Man." I have been dabbling in animation and I had not found an effective method of erasing a character after it was drawn. From reading your article I discovered - ? CHR$(125), a milestone in my computer education. I now see the light!
Having read the article "Start Interrupting" (ANTIC, June 1983), I wrote a display list interrupt to turn the background color to black at the bottom of the screen in one of my programs. However, whenever the program performs input or output to the disk or printer, the whole screen goes black. Can this be corrected?
Your display list interrupt works by writing a new color (black) directly to the screen background hardware register after the twenty-first mode line. When the last mode line is drawn, a stage two VBI (vertical blank interrupt) occurs which updates the hardware register from the shadow register which contains the color blue.
Disk and printer I/O are time-criticle routines; during these, stage two VBI routines are not performed. That is why the screen stays black - the hardware register is not being updated. As soon as time-critical I/O is finished, the screen returns to its proper colors.
Disk and printer I/O are time-criticle routines; during these, stage two VBI routines are not performed. That is why the screen stays black - the hardware register is not being updated. As soon as time-critical I/O is finished, the screen returns to its proper colors.--ANTIC ED