Modifications Or Corrections To Previous Articles
VIC Worm Of Bemer
The listing for the VIC version of this game from the April issue (p. 74) contains Commodore 64 color codes which are not available on the VIC. These cause no serious problems, but the |<6>| or |<8>| character should be omitted in lines 7715, 7730, and 10000.
Super Directory For 64 And IBM
Commodore 64 users have found that using "Super Directory" (Program 1, p. 173) from the April issue to load and run programs can cause problems if the program selected uses the BASIC function RND. An overflow error will be encountered because Super Directory alters a memory location used in calculating random numbers. Brian T. Bennett has discovered that the problem can be solved by changing line 1150 to:
1150 POKE 139, 128 : GOTO 5000
The IBM version (Program 4, p. 176) cannot be used to load and run programs from a disk with the write-protect notch covered. This is due to the way DOS handles the Write-Protect Error. Note also that the program as presented will work only with DOS 2.0 or 2.1.
Tl Mozart Machine
Music aficionados may have detected a sour note in the tunes played by the TI version of this program from the January issue (Program 4, p. 168). The solution is to change the next to the last DATA element in line 480 from 287 to 587. Thanks to Kevin M. Norberg for this correction.
Atari Roader Improvements
Mike La Fave offers the following revision to this game from the March issue (Program 3, p. 70) to allow you to steer your racer with a joystick instead of the keyboard:
220 P = STICK(0) : IF P = 11 THEN N = N - 1 : GOTO 240 230 IF P = 7 THEN N = N + 1
Also, Keith Christleib suggests the following additions to include an engine sound as the car speeds down the track:
201 SOUND 3, 135, 2, 9 315 SOUND 3, 0, 0, 0
Reader Mike Levesque notes that the "64Key" program from the February issue (p. 160) uses the same area of memory as the DOS Wedge program supplied with the 1541 demo disk. To use these two valuable utilities together, he suggests changing the following lines:
20 FOR 1 = 51789 TO 51967 50 IF X<>23734 THEN PRINT "THERE IS AN ERROR IN YOUR DATA STATEMENTS" : END 60 PRINT"SYS 51789 TO ACTIVATE" : END
Next, change the DATA element 205 to 202 in the following lines: 100, 120, 130, 140, 150, 190, 220, 300, and 320. Finally, remove the, 0 from the end of line 430 and delete line 440. These changes relocate 64Key to the area immediately above the Wedge, allowing the two to coexist in harmony and still leaving locations 49152-51788 free for other uses.
64 Explorer RESET Switch
Columnist Larry Isaacs recommends a revision of RESET switch circuit for the 64 featured in his March column (p. 172). Larry based his design on the schematic diagram of the 64 included in the Programmer's Reference Guide. However, the actual circuitry in the 64 has since been slightly modified and, as a result, it is no longer safe to ground the RESET line directly. Although Larry has used his switch for several months without incident, it presents some risk of damaging the chips inside the computer, and you should consider this before attempting to use the switch on your computer.
As an alternative, Lester Iwamasa of Custom Concepts, who pointed out the danger of using the original circuit, has provided the following circuit which performs a RESET without the possibility of damage to the computer:
If you're not up to building this circuit yourself, you can obtain it for $21.95, plus $2.00 shipping, from:
30117 3rd Pl. SW
Federal Way, WA 98003