Here is the plain version with ECMA-48 color control functions, the game itself, and the game metadata.
This is documentation for the Russian roulette game provided in the sixth edition of VIPER magazine. Firstly, follows is a view of the program when it is first loaded into the tool:
200-201 0512-0513 ▀▀ ▄▀▄▀ 650A 25866 V5 ← 010
202-203 0514-0515 ▄ ▀ ▄ ▀ 2288 08840 Call 0648
204-205 0516-0517 ▀▀▀▀▄ █ F20A 61962 V2 ← key
206-207 0518-0519 ▀▀ ▄▀█ C305 49925 V3 ← ??? AND 005
208-209 0520-0521 ▀ ▄▀▀ 4304 17156 Skip next if V3 <> 004
20A-20B 0522-0523 ▄█ █ 1232 04658 Jump to 0562
20C-20D 0524-0525 ▀▄▀▄▄ █ A25A 41562 I ← 0602
20E-20F 0526-0527 ▀▀▄ ▀ 6110 24848 V1 ← 016
210-211 0528-0529 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
212-213 0530-0531 ▀▄▀▄▄▄█▄ A25F 41567 I ← 0607
214-215 0532-0533 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
216-217 0534-0535 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
218-219 0536-0537 ▀▄█ ▄▀ A264 41572 I ← 0612
21A-21B 0538-0539 ▀█ ▀ 6120 24864 V1 ← 032
21C-21D 0540-0541 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
21E-21F 0542-0543 ▀█▄ ▀ 6430 25648 V4 ← 048
220-221 0544-0545 ▀▀▀█ █ ▄ F415 62485 delay ← V4
222-223 0546-0547 ▀▀▀▀ █▄▄ F407 62471 V4 ← delay
224-225 0548-0549 ▀▀ ▀ 3400 13312 Skip next if V4 = 000
226-227 0550-0551 ▄▀ █ 1222 04642 Jump to 0546
228-229 0552-0553 ▄▄▄ 00E0 00224 Clear the screen
22A-22B 0554-0555 ▄███▄█▄█ 75FF 30207 V5 ← V5 + 255
22C-22D 0556-0557 ▀ ▀ ▀ 4500 17664 Skip next if V5 <> 000
22E-22F 0558-0559 ▄ ▀ ▄█ 1246 04678 Jump to 0582
230-231 0560-0561 ▀ █ 1202 04610 Jump to 0514
232-233 0562-0563 ▀▄█ ▄ ▀▄ A269 41577 I ← 0617
234-235 0564-0565 ▀▀▄ ▀ 6110 24848 V1 ← 016
236-237 0566-0567 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
238-239 0568-0569 ▀▄█ ▄▄█ A26E 41582 I ← 0622
23A-23B 0570-0571 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
23C-23D 0572-0573 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
23E-23F 0574-0575 ▀▄█▄ █▄ A273 41587 I ← 0627
240-241 0576-0577 ▀█ ▀ 6120 24864 V1 ← 032
242-243 0578-0579 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
244-245 0580-0581 ▄ ▀ ▄▀ 1244 04676 Jump to 0580
246-247 0582-0583 ▀▄█▄▄ ▀ A278 41592 I ← 0632
248-249 0584-0585 ▀▀▄ ▀ 6110 24848 V1 ← 016
24A-24B 0586-0587 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
24C-24D 0588-0589 ▀▄█▄▄▄▀▄ A27D 41597 I ← 0637
24E-24F 0590-0591 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
250-251 0592-0593 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
252-253 0594-0595 █ ▀ █ A282 41602 I ← 0642
254-255 0596-0597 ▀█ ▀ 6120 24864 V1 ← 032
256-257 0598-0599 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
258-259 0600-0601 ▄ █▄ ▀ 1258 04696 Jump to 0600
25A-25B 0602-0603 █▀▀ █ E888 59528
25C-25D 0604-0605 █ █ 8888 34952
25E-25F 0606-0607 ███ ███ EEEE 61166
260-261 0608-0609 █ █ 4848 18504 Skip next if V8 <> 072
262-263 0610-0611 ▄█▄ █▄▄ 48EE 18670 Skip next if V8 <> 238
264-265 0612-0613 █▄▀ █ █ AACA 43722 I ← 2762
266-267 0614-0615 ██ ▀ ▀ CAC0 51904 VA ← ??? AND 192
268-269 0616-0617 █▄█▄▀▄█▄ AAF7 43767 I ← 2807
26A-26B 0618-0619 █▄█ █▄█ 5577 21879
26C-26D 0620-0621 ▄█▄█ █ █ 55F5 22005
26E-26F 0622-0623 ██ █ █ 6565 25957 V5 ← 101
270-271 0624-0625 █ ▀▄█ █ 554D 21837
272-273 0626-0627 ▄█ ▄▀█ █ 4DD5 19925 Skip next if VD <> 213
274-275 0628-0629 █ █ █ 1515 05397 Jump to 1301
276-277 0630-0631 ▄█ ▄ ▄ ▄ 40D5 16597 Skip next if V0 <> 213
278-279 0632-0633 █ █ ▀█ 8B89 35721
27A-27B 0634-0635 █ ▄ █ █ 89A9 35241
27C-27D 0636-0637 █▀▄█▀ █▀ DBB2 56242 Draw 08×02 at VB,VB; VF ← XOR
27E-27F 0638-0639 █▀▄ █ 322A 12842 Skip next if V2 = 042
280-281 0640-0641 ▄ █ ▀█ 26A2 09890 Call 1698
282-283 0642-0643 █ █ █ █ AAAA 43690 I ← 2730
284-285 0644-0645 ▀ ▀ ▀ ▀ AA00 43520 I ← 2560
286-287 0646-0647 ▀ █ ▀ ▀ AA20 43552 I ← 2592
288-289 0648-0649 █ ▀▄ █ A292 41618 I ← 0658
28A-28B 0650-0651 ▀▀▄▄▀▀ 6618 26136 V6 ← 024
28C-28D 0652-0653 ▀▀▄ ▀▀▀ 6710 26384 V7 ← 016
28E-28F 0654-0655 ▀█▄█ ██▄ D677 54903 Draw 08×07 at V6,V7; VF ← XOR
290-291 0656-0657 ▄▄▄ ▄▄▄ 00EE 00238 Return
292-293 0658-0659 ▄ █ ▄ 082A 02090 Jump to COSMAC VIP 2090
294-295 0660-0661 ██▀▀▀██ 7F63 32611 VF ← VF + 099
296-297 0662-0663 ██ ▀ ██ 6B63 27491 VB ← 099
298-299 0664-0665 ███████ 7F7F 32639 VF ← VF + 127
29A-29B 0666-0667 ██▄▄▄██ 637F 25471 V3 ← 127Follows now is the fully annotated view of the program when it is loaded into the tool:
200-201 0512-0513 ▀▀ ▄▀▄▀ 650A 25866 V5 ← 010
202-203 0514-0515 ▄ ▀ ▄ ▀ 2288 08840 begin Call draw gun
204-205 0516-0517 ▀▀▀▀▄ █ F20A 61962 V2 ← key
206-207 0518-0519 ▀▀ ▄▀█ C305 49925 V3 ← ??? AND 005
208-209 0520-0521 ▀ ▄▀▀ 4304 17156 Skip next if V3 <> 004
20A-20B 0522-0523 ▄█ █ 1232 04658 Jump to lose
20C-20D 0524-0525 ▀▄▀▄▄ █ A25A 41562 I ← cl
20E-20F 0526-0527 ▀▀▄ ▀ 6110 24848 V1 ← 016
210-211 0528-0529 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
212-213 0530-0531 ▀▄▀▄▄▄█▄ A25F 41567 I ← ic
214-215 0532-0533 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
216-217 0534-0535 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
218-219 0536-0537 ▀▄█ ▄▀ A264 41572 I ← k!!
21A-21B 0538-0539 ▀█ ▀ 6120 24864 V1 ← 032
21C-21D 0540-0541 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
21E-21F 0542-0543 ▀█▄ ▀ 6430 25648 V4 ← 048
220-221 0544-0545 ▀▀▀█ █ ▄ F415 62485 delay ← V4
222-223 0546-0547 ▀▀▀▀ █▄▄ F407 62471 delay V4 ← delay
224-225 0548-0549 ▀▀ ▀ 3400 13312 Skip next if V4 = 000
226-227 0550-0551 ▄▀ █ 1222 04642 Jump to delay
228-229 0552-0553 ▄▄▄ 00E0 00224 Clear the screen
22A-22B 0554-0555 ▄███▄█▄█ 75FF 30207 V5 ← V5 + 255
22C-22D 0556-0557 ▀ ▀ ▀ 4500 17664 Skip next if V5 <> 000
22E-22F 0558-0559 ▄ ▀ ▄█ 1246 04678 Jump to win
230-231 0560-0561 ▀ █ 1202 04610 Jump to begin
232-233 0562-0563 ▀▄█ ▄ ▀▄ A269 41577 lose I ← ba
234-235 0564-0565 ▀▀▄ ▀ 6110 24848 V1 ← 016
236-237 0566-0567 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
238-239 0568-0569 ▀▄█ ▄▄█ A26E 41582 I ← n
23A-23B 0570-0571 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
23C-23D 0572-0573 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
23E-23F 0574-0575 ▀▄█▄ █▄ A273 41587 I ← g!!
240-241 0576-0577 ▀█ ▀ 6120 24864 V1 ← 032
242-243 0578-0579 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
244-245 0580-0581 ▄ ▀ ▄▀ 1244 04676 self Jump to self
246-247 0582-0583 ▀▄█▄▄ ▀ A278 41592 win I ← w
248-249 0584-0585 ▀▀▄ ▀ 6110 24848 V1 ← 016
24A-24B 0586-0587 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
24C-24D 0588-0589 ▀▄█▄▄▄▀▄ A27D 41597 I ← in
24E-24F 0590-0591 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
250-251 0592-0593 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
252-253 0594-0595 █ ▀ █ A282 41602 I ← !!!!
254-255 0596-0597 ▀█ ▀ 6120 24864 V1 ← 032
256-257 0598-0599 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
258-259 0600-0601 ▄ █▄ ▀ 1258 04696 end Jump to end
25A 0602 ███ █ E8 232 cl
25B 0603 █ █ 88 136
25C 0604 █ █ 88 136
25D 0605 █ █ 88 136
25E 0606 ███ ███ EE 238
25F 0607 ███ ███ EE 238 ic
260 0608 █ █ 48 072
261 0609 █ █ 48 072
262 0610 █ █ 48 072
263 0611 ███ ███ EE 238
264 0612 █ █ █ █ AA 170 k!!
265 0613 ██ █ █ CA 202
266 0614 ██ █ █ CA 202
267 0615 ██ C0 192
268 0616 █ █ █ █ AA 170
269 0617 ████ ███ F7 247 ba
26A 0618 █ █ █ █ 55 085
26B 0619 ███ ███ 77 119
26C 0620 █ █ █ █ 55 085
26D 0621 ████ █ █ F5 245
26E 0622 ██ █ █ 65 101 n
26F 0623 ██ █ █ 65 101
270 0624 █ █ █ █ 55 085
271 0625 █ ██ █ 4D 077
272 0626 █ ██ █ 4D 077
273 0627 ██ █ █ █ D5 213 g!!
274 0628 █ █ █ 15 021
275 0629 █ █ █ 15 021
276 0630 █ 40 064
277 0631 ██ █ █ █ D5 213
278 0632 █ █ ██ 8B 139 w
279 0633 █ █ █ 89 137
27A 0634 █ █ █ 89 137
27B 0635 █ █ █ █ A9 169
27C 0636 ██ ██ ██ DB 219
27D 0637 █ ██ █ B2 178 in
27E 0638 ██ █ 32 050
27F 0639 █ █ █ 2A 042
280 0640 █ ██ 26 038
281 0641 █ █ █ A2 162
282 0642 █ █ █ █ AA 170 !!!!
283 0643 █ █ █ █ AA 170
284 0644 █ █ █ █ AA 170
285 0645 00 000
286 0646 █ █ █ █ AA 170
287 0647 █ 20 032
288-289 0648-0649 █ ▀▄ █ A292 41618 draw gun I ← gun
28A-28B 0650-0651 ▀▀▄▄▀▀ 6618 26136 V6 ← 024
28C-28D 0652-0653 ▀▀▄ ▀▀▀ 6710 26384 V7 ← 016
28E-28F 0654-0655 ▀█▄█ ██▄ D677 54903 Draw 08×07 at V6,V7; VF ← XOR
290-291 0656-0657 ▄▄▄ ▄▄▄ 00EE 00238 Return
292 0658 █ 08 008 gun
293 0659 █ █ █ 2A 042
294 0660 ███████ 7F 127
295 0661 ██ ██ 63 099
296 0662 ██ █ ██ 6B 107
297 0663 ██ ██ 63 099
298 0664 ███████ 7F 127
299 0665 ███████ 7F 127
29A 0666 ██ ██ 63 099
29B 0667 ███████ 7F 127The register usage is as follows:
The program begins by initializing register 5 and then entering the prime loop of the program, which I name ``begin'' by convention, which starts with calling the draw gun routine:
200-201 0512-0513 ▀▀ ▄▀▄▀ 650A 25866 V5 ← 010
202-203 0514-0515 ▄ ▀ ▄ ▀ 2288 08840 begin Call draw gunThe prime loop, sans the draw gun routine, is responsible for the entire game. Once the routine returns, the program waits for input to simulate pulling the trigger and then generates the 1/4 chance of losing, jumping to the lose routine in that case:
204-205 0516-0517 ▀▀▀▀▄ █ F20A 61962 V2 ← key
206-207 0518-0519 ▀▀ ▄▀█ C305 49925 V3 ← ??? AND 005
208-209 0520-0521 ▀ ▄▀▀ 4304 17156 Skip next if V3 <> 004
20A-20B 0522-0523 ▄█ █ 1232 04658 Jump to loseOtherwise, the game displays ``CLICK!!'' drawn using three sprites:
20C-20D 0524-0525 ▀▄▀▄▄ █ A25A 41562 I ← cl
20E-20F 0526-0527 ▀▀▄ ▀ 6110 24848 V1 ← 016
210-211 0528-0529 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
212-213 0530-0531 ▀▄▀▄▄▄█▄ A25F 41567 I ← ic
214-215 0532-0533 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
216-217 0534-0535 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
218-219 0536-0537 ▀▄█ ▄▀ A264 41572 I ← k!!
21A-21B 0538-0539 ▀█ ▀ 6120 24864 V1 ← 032
21C-21D 0540-0541 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XORThe game then enters a delay of 48/60 of a second using a simple subloop:
21E-21F 0542-0543 ▀█▄ ▀ 6430 25648 V4 ← 048
220-221 0544-0545 ▀▀▀█ █ ▄ F415 62485 delay ← V4
222-223 0546-0547 ▀▀▀▀ █▄▄ F407 62471 delay V4 ← delay
224-225 0548-0549 ▀▀ ▀ 3400 13312 Skip next if V4 = 000
226-227 0550-0551 ▄▀ █ 1222 04642 Jump to delayThe game then clears the screen to ease screen management and decrements the game counter by adding two's complement negative one to the iteration counter. It then checks if the game has iterated the appropriate number of times and jumps to the win routine if so; if not, it finishes the loop:
228-229 0552-0553 ▄▄▄ 00E0 00224 Clear the screen
22A-22B 0554-0555 ▄███▄█▄█ 75FF 30207 V5 ← V5 + 255
22C-22D 0556-0557 ▀ ▀ ▀ 4500 17664 Skip next if V5 <> 000
22E-22F 0558-0559 ▄ ▀ ▄█ 1246 04678 Jump to win
230-231 0560-0561 ▀ █ 1202 04610 Jump to beginThe lose routine displays ``BANG!!'' drawn using three sprites and then ends the game. It is interesting to note that, as CHIP-8 lacks an instruction to exit the game, the game simply enters an infinite loop upon finishing:
232-233 0562-0563 ▀▄█ ▄ ▀▄ A269 41577 lose I ← ba
234-235 0564-0565 ▀▀▄ ▀ 6110 24848 V1 ← 016
236-237 0566-0567 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
238-239 0568-0569 ▀▄█ ▄▄█ A26E 41582 I ← n
23A-23B 0570-0571 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
23C-23D 0572-0573 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
23E-23F 0574-0575 ▀▄█▄ █▄ A273 41587 I ← g!!
240-241 0576-0577 ▀█ ▀ 6120 24864 V1 ← 032
242-243 0578-0579 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
244-245 0580-0581 ▄ ▀ ▄▀ 1244 04676 self Jump to selfThe win routine is identical in structure to the lose routine, but displays ``WIN!!!!'' instead and then ends the game:
246-247 0582-0583 ▀▄█▄▄ ▀ A278 41592 win I ← w
248-249 0584-0585 ▀▀▄ ▀ 6110 24848 V1 ← 016
24A-24B 0586-0587 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
24C-24D 0588-0589 ▀▄█▄▄▄▀▄ A27D 41597 I ← in
24E-24F 0590-0591 ▀▀▄▄ ▀ 6118 24856 V1 ← 024
250-251 0592-0593 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
252-253 0594-0595 █ ▀ █ A282 41602 I ← !!!!
254-255 0596-0597 ▀█ ▀ 6120 24864 V1 ← 032
256-257 0598-0599 ▀▀▄█ ▄ █ D135 53557 Draw 08×05 at V1,V3; VF ← XOR
258-259 0600-0601 ▄ █▄ ▀ 1258 04696 end Jump to endFollowing the prime loop are the CL, IC, K!, BA, N, G!!, W, IN, and !!!! sprites and an insignificant byte; it's reasonable to assume this byte is padding so that the following code is aligned to an even address; there's no reason seen for its particular value, however:
25A 0602 ███ █ E8 232 cl
25B 0603 █ █ 88 136
25C 0604 █ █ 88 136
25D 0605 █ █ 88 136
25E 0606 ███ ███ EE 238
25F 0607 ███ ███ EE 238 ic
260 0608 █ █ 48 072
261 0609 █ █ 48 072
262 0610 █ █ 48 072
263 0611 ███ ███ EE 238
264 0612 █ █ █ █ AA 170 k!!
265 0613 ██ █ █ CA 202
266 0614 ██ █ █ CA 202
267 0615 ██ C0 192
268 0616 █ █ █ █ AA 170
269 0617 ████ ███ F7 247 ba
26A 0618 █ █ █ █ 55 085
26B 0619 ███ ███ 77 119
26C 0620 █ █ █ █ 55 085
26D 0621 ████ █ █ F5 245
26E 0622 ██ █ █ 65 101 n
26F 0623 ██ █ █ 65 101
270 0624 █ █ █ █ 55 085
271 0625 █ ██ █ 4D 077
272 0626 █ ██ █ 4D 077
273 0627 ██ █ █ █ D5 213 g!!
274 0628 █ █ █ 15 021
275 0629 █ █ █ 15 021
276 0630 █ 40 064
277 0631 ██ █ █ █ D5 213
278 0632 █ █ ██ 8B 139 w
279 0633 █ █ █ 89 137
27A 0634 █ █ █ 89 137
27B 0635 █ █ █ █ A9 169
27C 0636 ██ ██ ██ DB 219
27D 0637 █ ██ █ B2 178 in
27E 0638 ██ █ 32 050
27F 0639 █ █ █ 2A 042
280 0640 █ ██ 26 038
281 0641 █ █ █ A2 162
282 0642 █ █ █ █ AA 170 !!!!
283 0643 █ █ █ █ AA 170
284 0644 █ █ █ █ AA 170
285 0645 00 000
286 0646 █ █ █ █ AA 170
287 0647 █ 20 032Lastly, there is the draw gun routine, which merely displays the gun sprite and then returns. As it is only called from one location, it would be simple to move this routine and then eliminate the call instruction, the return instruction, and the padding byte immediately following this routine:
288-289 0648-0649 █ ▀▄ █ A292 41618 draw gun I ← gun
28A-28B 0650-0651 ▀▀▄▄▀▀ 6618 26136 V6 ← 024
28C-28D 0652-0653 ▀▀▄ ▀▀▀ 6710 26384 V7 ← 016
28E-28F 0654-0655 ▀█▄█ ██▄ D677 54903 Draw 08×07 at V6,V7; VF ← XOR
290-291 0656-0657 ▄▄▄ ▄▄▄ 00EE 00238 Return
292 0658 █ 08 008 gun
293 0659 █ █ █ 2A 042
294 0660 ███████ 7F 127
295 0661 ██ ██ 63 099
296 0662 ██ █ ██ 6B 107
297 0663 ██ ██ 63 099
298 0664 ███████ 7F 127
299 0665 ███████ 7F 127
29A 0666 ██ ██ 63 099
29B 0667 ███████ 7F 127