Paperboy (USA)

Paperboy (USA) is on a CNROM board with 32,768 bytes of program. A crawl of 8,000 steps from power-on kept 39 paths that found new code. Played back over 101,779 frames, they executed 9,018 bytes of it, 28 percent.

What the rules named

The 276 routines the runs entered

Every place the game's code was entered, by a call, an interrupt or a jump through a table. The ones a rule named come first, with what the rule saw, and their names in the listing say what they are: a poll, an engine, a drain.

at	its name in the listing	entered by	times	what it is, and the evidence
$86BE	`handlers_86BE`	a call	156,809	The handler kept in memory: jumps 132,729, places it landed 79, address copied from $0008,$000D,$04B6,$04CF
$80EA	`poll_80EA`	a call	85,719	The poll: port $4016, reads a frame 13, strobes a frame 5 The poll: port $4017, reads a frame 8, strobes a frame 5
$8006	`nmi`	each frame (NMI)	39,502	The game inside the interrupt: frames it ran in 39,502, frames in all 39,619, the spin is at $80A1 The scroll writer: frames it ran in 39,502, writes in the blank 77,486
$853E	`drain_853E`	a call	38,791	The palette writers: frames it ran in 38,791, writes 1,585 The picture writer: frames it ran in 38,791, writes 9,666, in the blank 7,582, while drawing 2,084
$839E	`compare_839E`	a call	38,770	Where two things are compared: instructions 2, pairs of bytes 77, bytes in all 19, times compared 210,252, X positions at $0019,$001A,$001B,$001C,$001D,$001E,$001F,$0020,$0021,$0022,$0023,$0024, Y positions at $004F,$0050,$0051,$0052,$0057,$07D5 The sprite writers: frames it ran in 38,796, writes to the sprite page 4,871,921
$9C26	`engine_9C26`	a call	23,178	The jump engine: tables 3, jumps through them 11,578
$82D9	`compare_82D9`	a call	18,575	Where two things are compared: instructions 2, pairs of bytes 7, bytes in all 9, times compared 17,237, X positions at $001D,$001E,$001F,$0020,$0025, Y positions at $0050,$0051,$0052,$0057
$98C8	`engine_98C8`	a call	12,712	The jump engine: tables 4, jumps through them 5,608
$861A	`compare_861A`	a call	12,584	Where two things are compared: instructions 1, pairs of bytes 1, bytes in all 2, times compared 6, X positions at $001E,$0025
$8722	`engine_8722`	a call	4,678	The jump engine: tables 9, jumps through them 4,236
$8706	`engine_8706`	a call	4,674	The jump engine: tables 36, jumps through them 2,649
$8E3C	`random_8E3C`	a call	2,395	The random byte: frames it ran in 3,325, bytes $00C8, rotates 2, exclusive-ors 1
$A993	`dispatch_A993`	a table	1,729	The sound driver: frames it ran in 1,825, writes 4,436
$9543	`engine_9543`	a call	1,511	The jump engine: tables 1, jumps through them 2
$8A69	`engine_8A69`	a call	1,108	The jump engine: tables 1, jumps through them 6
$90B8	`compare_90B8`	a call	832	Where two things are compared: instructions 1, pairs of bytes 3, bytes in all 4, times compared 822, X positions at $001E,$001F,$0020,$0025
$A24E	`engine_A24E`	a call	186	The jump engine: tables 1, jumps through them 1
$80A4	`bank_80A4`	a call	157	The bank switch: writes 314, in the blank 14, while drawing 300
$80B3	`engine_80B3`	a call	58	The jump engine: tables 1, jumps through them 58
$A50B	`handlers_A50B`	a call	42	The handler kept in memory: jumps 223, places it landed 6, address copied from $0002,$0003
$8D16	`dispatch_8D16`	a table	4	The handler kept in memory: jumps 404, places it landed 13, address copied from $009D,$009E
$81F0		a call	305,019
$81B6		a call	60,620
$94FC		a table	46,208
$867E		a call	38,791
$A4E2		a call	30,782
$9F44		a table	25,445
$9FA4		a call	25,445
$9FB6		a call	25,445
$834D		a call	24,172
$84F3		a call	23,271
$8044		a call	23,207
$8DB6		a table	23,207
$8F86		a call	23,178
$A462		a call	23,178
$9BE0		a call	23,176
$832B		a call	21,746
$8618		a call	20,167
$9B65		a table	19,695
$865E		a call	19,064
$A512		a call	18,247
$A4CD		a call	17,158
$A522		a call	16,129
$8A70		a call	15,516
$8151		a call	14,523
$8A76		a call	13,400
$8A80		a call	13,002
$9C1C		a call	11,578
$8A0A		a call	11,498
$8A59		a call	11,100
$85C4		a call	9,698
$908B		a table	9,607
$8DC8		a call	8,919
$8FD6		a call	7,457
$9E98		a call	7,204
$8629		a call	6,264
$88A4		a table	5,358
$872F		a call	5,145
$8319		a call	4,907
$84EA		a call	4,173
$9BC3		a table	3,473
$9899		a table	3,355
$98A4		a table	3,220
$98B2		a table	3,157
$98BD		a table	2,980
$81AA		a call	2,491
$864D		a call	2,449
$A4E6		a call	2,364
$9E50		a table	2,121
$9B25		a table	2,119
$817A		a call	2,080
$818B		a call	2,080
$9AB2		a table	2,055
$A537		a table	2,010
$9E62		a table	1,834
$A36F		a call	1,798
$9E7A		a table	1,662
$A356		a table	1,648
$95A4		a table	1,623
$95C4		a call	1,623
$9E8C		a table	1,589
$862B		a call	1,572
$864F		a call	1,570
$A69B		a table	1,454
$A87C		a table	1,281
$8790		a table	1,277
$8883		a table	1,274
$A90E		a table	1,258
$9698		a call	1,224
$8A65		a table	1,108
$A1D6		a table	894
$86CC		a call	892
$9553		a table	858
$9594		a call	858
$860F		a call	843
$98A1		a table	831
$98AC		a table	807
$98BA		a table	783
$952A		a table	762
$98C5		a table	760
$953D		a table	749
$8D8D		a table	681
$A61D		a table	558
$8678		a call	502
$8290		a call	477
$90A5		a table	426
$90B2		a table	406
$8505		a call	404
$8530		a call	404
$863A		a call	396
$A1C2		a call	384
$907B		a call	315
$8643		a call	256
$A7BA		a table	252
$8261		a call	223
$82B8		a call	223
$A248		a call	212
$8244		a call	198
$986E		a table	198
$A4BD		a table	198
$A1AF		a table	193
$A1BC		a table	191
$866F		a call	183
$9494		a table	170
$A683		a table	166
$94CE		a table	154
$A36B		a table	150
$94F0		a table	149
$94F5		a table	149
$9883		a table	140
$A5E1		a table	128
$9527		a table	127
$953A		a table	127
$9057		a table	121
$A208		a table	110
$86C1		a call	109
$825C		a call	104
$9066		a table	104
$A1F6		a table	104
$95BD		a table	101
$95C1		a call	101
$811A		a call	96
$94E3		a table	92
$9075		a table	90
$A502		a table	83
$A50A		a table	83
$8716		a call	80
$9652		a call	72
$94EB		a table	62
$A605		a table	62
$86D5		a call	56
$91B1		a call	56
$9235		a call	56
$E100		a call	53
$A235		a table	48
$A21B		a table	47
$A242		a table	47
$852A		a call	44
$A228		a table	44
$9E5F		a table	43
$87BC		a table	42
$87CA		a table	42
$87D9		a table	42
$87F1		a table	42
$8813		a table	42
$882D		a table	42
$883E		a table	42
$885C		a table	42
$8861		a table	42
$8868		a table	42
$887B		a table	42
$A7B0		a table	42
$8782		a table	41
$8785		a table	41
$A4ED		a call	41
$8048		power-on	39
$8092		a table	39
$809A		a table	39
$813E		a call	39
$8754		a table	39
$9BDE		a call	39
$88C8		a table	36
$95CB		a call	36
$9E4D		a table	36
$9E74		a table	36
$9AAF		a table	34
$9E89		a table	34
$889C		a table	33
$821D		a call	31
$9AA1		a table	31
$89CC		a table	29
$89D1		a table	29
$89D6		a table	29
$9B50		a table	29
$9F31		a table	29
$9F36		a table	29
$A7C9		a call	29
$A7DC		a table	29
$A7E3		a table	29
$A7EA		a table	29
$A805		a table	29
$A897		a table	29
$A929		a table	29
$90A2		a table	28
$9F24		a call	28
$8568		a call	27
$8927		a table	27
$8928		a table	27
$89DC		a call	27
$8A09		a table	27
$9ACA		a call	27
$9D37		a call	27
$9EF8		a call	27
$90AF		a table	26
$9AC4		a table	24
$9493		a table	21
$9A84		a table	18
$A58D		a table	16
$A5B2		a table	16
$A1F3		a table	15
$9E43		a table	14
$A205		a table	14
$88F0		a table	13
$9159		a call	13
$916E		a table	13
$917B		a table	13
$9486		a call	13
$A1AC		a table	13
$8A8B		a call	12
$8A94		a table	12
$A1B9		a table	12
$9054		a table	11
$9063		a table	11
$8AA8		a call	10
$8AB0		a table	10
$8AB1		a table	10
$8AB6		a table	10
$9072		a table	10
$9BB2		a table	10
$8AC5		a table	9
$88FB		a table	8
$890F		a table	8
$8A52		a table	8
$9481		a call	8
$A218		a table	7
$A225		a table	7
$8917		a table	6
$A232		a table	6
$A23F		a table	6
$8953		a table	5
$8AF7		a table	5
$891C		a table	4
$8AD1		a table	4
$8D05		a table	4
$8D27		a table	4
$8D30		a table	4
$8D36		a table	4
$9FD1		a call	4
$A12B		a call	4
$A40A		a call	4
$879B		a table	3
$951D		a table	3
$95BA		a table	3
$875F		a table	2
$8945		a table	2
$8979		a table	2
$8DB5		a table	2
$999C		a table	2
$A4C9		a table	2
$A633		a table	2
$8DA0		a table	1
$904A		a table	1
$9975		a table	1
$9C29		a table	1
$A1A7		a table	1
$A1C5		a table	1

Where it waits

Loops a rule named that sit inside a routine and are not themselves a place the code is entered.

at	its name in the listing	what it is, and the evidence
$80A1	`spin_80A1`	The idle spin: turns 271,492,681, turns a frame 6,852

The tables it jumps through

A table of addresses the game picks one from. Some sit right after a call to a jump engine; others are anywhere in the cartridge, and we find them by where the address the game jumped through was loaded from. Some games jump by pushing an address and returning to it, and some keep a table as two, the low bytes of its addresses in one place and the high bytes in another; both are found the same way. An entry is counted as far as the runs saw one taken; the true table may be longer. The last column is the byte of memory whose value picked the entry, where we could follow it: the game's mode, or what one of its objects is doing.

at	reached	entries	taken	chosen by the byte at
$98AA	by a return	1	1

The memory its routines share

762 bytes of memory were written by one routine and read by another, and 52 places were reached through an index, which is what a table or a set of object slots in memory looks like.

The console's 2,048 bytes of memory, one row for each 256. A numbered span is a column of one of the object tables drawn below, counted in the same order, as long as the table and filled as it is there. Where a table's columns overlap, its things lie one after another, each with all its properties, so the table is one outline with a mark where each property starts. A dark square is a position a rule saw compared. A tick under a row is one of the 24 busiest shared bytes. The second row is the page the processor keeps its stack in. Reaches through an index that belong to no table are not drawn: the loops that clear memory reach nearly every byte.

Reaches through an index: those that hold positions, then the longest

from	bytes reached	instructions	positions it holds
$003F	25	22	5 down
$000D	25	17	13 across
$0200	253	2
$0300	212	8
$0301	211	4
$0302	193	2
$0201	177	1
$0202	177	1
$0203	177	1
$0773	80	3
$0535	62	3
$05CD	44	8

What travels with a position

Arrays that at least two routines step through together with an array of positions, across the same range. That is what a table of the things on the screen looks like in memory: one array for each property, one slot for each thing. We can say which arrays hold positions, which of the others get added into them, which is what a speed does, which pick the way through a jump table, which is what a state or a kind does, and which are only ever counted down, which is what a timer does. What the rest hold is not named yet.

Table 1: 5 arrays of up to 25 slots that 25 routines step through together. Each column is an array at its address and each row a slot, so one thing on the screen is one row across all of them. X and Y are positions, and the darker squares are the slots a rule saw compared. + is added into a position, which is what a speed does. → chose a jump, which is what a state or a kind does. ↓ is only ever counted down, which is what a timer does. A plain outline travels with them and is not named yet.

slots	arrays	routines	positions across	positions down	added into them	choosing a jump	counted down	travelling with them
25	5	25	$000D	$003F				$0026, $0058, $0071

The 24 busiest shared bytes

byte	reads and writes	routines writing	routines reading
$0000	3,832,705	6	6
$009E	1,765,306	6	6
$009D	1,765,286	4	6
$0450	1,548,190	3	4
$0094	1,032,023	3	3
$0001	942,470	6	6
$0095	727,004	3	3
$0002	619,366	6	6
$0451	594,190	5	6
$0097	519,015	2	1
$0098	385,524	1	6
$0005	379,892	2	6
$00B1	255,097	4	2
$0006	193,856	4	6
$0025	163,118	3	6
$0007	139,445	4	6
$044B	137,742	6	6
$0099	122,733	1	6
$003E	121,721	2	3
$041F	117,721	6	6
$0438	117,719	6	6
$04F9	117,194	6	6
$04FA	114,323	6	6
$04FB	114,305	6	6

This page shows none of the game's bytes. The listing these figures were read from stays with the cartridge.

All the games