Machine Code and Your TV Screen 3:4.
Figure 1 will work as described without a 16K RAM pack. If you use the 16K, the screen is automatically filled up with spaces. Thus an “empty” line consists not of just the character 118 (the “enter” character), but of 32 spaces (character 0) followed by the “enter” character.
Figures 3 and 4:
70 IF A<64 THEN GOTO 50Figure 7:
120 GOTO 20For those especially desperate for a machine code translation of Figure 7, see Figure 1.
Figure 1.
Basic
Line Machine
number Code Label Mnemonics
20 237, 91, 12, 64 TWENTY: LD DE, (16396)
30 33, 20, 0 LD HL, 20
40 25 ADD HL, DE
50 126 FIFTY: LD A, (HL)
60 60 INC A
70 254, 38 CP 38
56, 5 JR C, ONE-TEN
80 54, 28 LD (HL), 28
90 43 DEC HL
100 24, -11 JR FIFTY
110 119 ONE-TEN: LD (HL), A
120 24, -22 JR TWENTY
Payroll 3:5, p. 4.
Change:
978 IF M$="Z" THEN GOTO 975PCB Differences 3:5
P. 4, col. 2, 1st par.
AB-A15 should be A8-A15.
The Logical Operators 3:5
P. 77, col. 3, last line:
(.9 OR P>=100)Brick Buster 3:5
The game worked for us with the code as printed in Figure 2. However, reader Carl S. Lucas, Jr., found it necessary to change the code at 40E4 from DB04 to DBFE in order to make the paddle move. This change also worked for us.
Line notes:
120: A (30)
190: Space (31)
Extensions to Basic 3:5
Figure 1.
500 REM ABE,IKE,Listings 4-8: Omit lines 1-5 in each.
The next to last paragraph of the article should begin: “You can plot…”
The author reports a minor bug that sometimes causes data to be misread. To correct the bug, type the programs as instructed in the article if you have not already done so. LOAD Listing 2 from tape, but do not press ENTER. Instead press EDIT, STOP, and then ENTER. Next type in:
POKE 16525,6
POKE 16533,32
RUNSAVE Listing 2 back to tape.