Glitchoidz Report

A Machine Code Graphics Line-Drawing Subroutine, 2:6.

Listing 3: Delete one INC HL at address 40A1H

Listing 6: Insert equals signs between the letters and numbers in the LET statements.

Making Backups for Machine Language Tapes, 3:1.

Section 2. Copying with PEEK and POKE.

The second paragraph should begin: PRINT PEEK 16388+256*PRINT PEEK 16389 . . .

In the third paragraph the SAVE directions should read: To SAVE, enter GOTO 370 . . .

A Small Business Payroll Program, 3:2.

Add to the menu routines the marital status options: 1—single; 2—married; 3—head of household.

Math Support for Your ZX81, 3:2.

The alternate lines referred to in the last paragraph are:

870 INPUT A$
880 IF A$="" THEN GOTO 910
890 INPUT B$
900 GOTO 800
910 CLS
920 RUN

To superimpose graphs, add:

810 FOR X=-W TO W
830 INPUT Y

To improve response to the menu:

40 LET A=VAL INKEY$*150
50 CLS
60 GOTO A

Minotaur, 3:2.

Enter the list of variables in the immediate mode (i.e., without line numbers; e.g., LET A=1). A through I=1; J=512; K=16396; L=33; O=0; P=1; Q=2; R=3; S=5; T=20; U=31; V=128. Check by pressing PRINT (variable letter) and ENTER. Do not use RUN or CLEAR since these wipe out the variables.

To start type GOTO P; when the cursor appears, enter the density (0-1; try .35). To restart at the same density, type GOTO T. To set up the same maze again, press BREAK (except when entering density), type in RAND n (n = a number from 1 to 16535). Use the same number to repeat the maze. After the RAND command, type GOTO T to start. At density .35, RAND 19, RAND 20, and RAND 40 produce challenging mazes. The author would appreciate reports of “good numbers”; be sure to include the density setting.

Knowing Your Strengths, 3:2.

The author comments:

One of your astute readers in translating the program into TRS-80 Basic caught an unnecessary negative and a flow error which gives spurious results when attempting to RECALCulate new section or material sections. Make the following corrections:

Changes:

1545 IF N=4 THEN GOTO 2050
2140 LET S2=(W*L)/6*Z)

1545 corrects the flow and 2140 eliminates the unnecessary negative.

Add:

3005 IF N=4 THEN GOTO 3020
3035 IF N=4 THEN GOTO 3050
3075 IF N=4 THEN GOTO 3090

These skip the W, L, and X1 inputs.

Eliminating the printout (line 1622) will save screen space.

To eliminate unnecessary, screen consuming decimal places change:

3505 PRINT ". . . PT.)="; INT
S2;"#PSI"

Some additional output I have found helpful:

3515 PRINT "STRESS="; INT (100/(S
/32));"#PCT. OF YIELD"