Mega Apocalypse.txt

https://youtu.be/nbmgK4fMPtM




.C:becf   AE EC BD   LDX $BDEC
.C:bed2   BD 80 04   LDA $0480,X
.C:bed5   4A         LSR A
.C:bed6   4A         LSR A
.C:bed7   A8         TAY
.C:bed8   BD 80 04   LDA $0480,X
.C:bedb   79 D1 BF   ADC $BFD1,Y
.C:bede   9D 80 04   STA $0480,X
.C:bee1   BD 80 02   LDA $0280,X
.C:bee4   79 D1 BF   ADC $BFD1,Y
.C:bee7   9D 80 02   STA $0280,X
.C:beea   BC 00 02   LDY $0200,X
.C:beed   D9 6F BE   CMP $BE6F,Y
.C:bef0   90 03      BCC $BEF5






.C:61cc   A2 7F      LDX #$7F
.C:61ce   8E EC BD   STX $BDEC
.C:61d1   A9 40      LDA #$40
.C:61d3   9D 00 03   STA $0300,X
.C:61d6   A9 FF      LDA #$FF
.C:61d8   9D 80 03   STA $0380,X
.C:61db   CA         DEX
.C:61dc   10 F3      BPL $61D1




break bf5e
Removes old star position, plots new star position



NMI vector at $21 for sample playback
Yes, stored into $d418 which is SID volume
$2c and $55 store sample data into volume
It has upper and lower nybble shifting for each sample byte


https://youtu.be/nbmgK4fMPtM

00:12 Introduction
00:24 Tape version
00:47 Cyberload turbo load
07:00 Making a single compressed file
10:38 Game ues a bitmap screen
11:20 Sprites usage, bullets and stars
12:04 Is this a large lookup table?
13:00 Matching stars motion with memory access
14:40 Experimenting to understand code logic
16:30 Looking at the stars update code
21:00 More stars in the title screen
22:00 Understanding the star draw logic
24:00 Very quick star remove and draw code
30:21 Sound sample memory and ode