Replacing data in NES ROMS

[Whipon]

I played a bit with Destiny of an Emperor (U) [!] {NES}.
I managed to hack it in the following way:


First I'll post the RAM Addresses of the game I used to hack it:

; [COLOR="RoyalBlue"]Destiny of an Emperor (U)
#1 6076-03-98967F	Money
#1 6079-03-98967F	Food
#1 60D0-03-01869F	General 1 - Max Soldiers
#1 6160-03-01869F	General 1 - Current Soldiers
#1 619C-01-FF		General 1 - Strength
#1 61A8-01-FF		General 1 - Intelligence
#1 60D4-03-01869F	General 2 - Max Soldiers
#1 6164-03-01869F	General 2 - Current Soldiers
#1 619D-01-FF		General 2 - Strength
#1 61A9-01-FF		General 2 - Intelligence
#1 60D8-03-01869F	General 3 - Max Soldiers
#1 6168-03-01869F	General 3 - Current Soldiers
#1 619E-01-FF		General 3 - Strength
#1 61AA-01-FF		General 3 - Intelligence
#1 60DC-03-01869F	General 4 - Max Soldiers
#1 616C-03-01869F	General 4 - Current Soldiers
#1 619F-01-FF		General 4 - Strength
#1 61AB-01-FF		General 4 - Intelligence
#1 60E0-03-01869F	General 5 - Max Soldiers
#1 6170-03-01869F	General 5 - Current Soldiers
#1 61A0-01-FF		General 5 - Strength
#1 61AC-01-FF		General 5 - Intelligence
#1 60E4-03-01869F	General 6 - Max Soldiers
#1 6174-03-01869F	General 6 - Current Soldiers
#1 61A1-01-FF		General 6 - Strength
#1 61AD-01-FF		General 6 - Intelligence
#1 60E8-03-01869F	General 7 - Max Soldiers
#1 6178-03-01869F	General 7 - Current Soldiers
#1 61A2-01-FF		General 7 - Strength
#1 61AE-01-FF		General 7 - Intelligence
#1 61F8-02-FFFF		Tactic Points - Max
#1 61FB-02-FFFF		Tactic Points - Current
#1 61FE-02-0000		Tactic Points - Used
#1 65A0-01-05		General 1 - Tactic 1
#1 65A1-01-0A		General 1 - Tactic 2
#1 65A2-01-0F		General 1 - Tactic 3
#1 65A3-01-13		General 1 - Tactic 4
#1 65A4-01-1E		General 1 - Tactic 5
#1 65A5-01-1A		General 1 - Tactic 6
#1 65A6-01-05		General 2 - Tactic 1
#1 65A7-01-0A		General 2 - Tactic 2
#1 65A8-01-0F		General 2 - Tactic 3
#1 65A9-01-13		General 2 - Tactic 4
#1 65AA-01-1E		General 2 - Tactic 5
#1 65AB-01-1A		General 2 - Tactic 6
#1 65AC-01-05		General 3 - Tactic 1
#1 65AD-01-0A		General 3 - Tactic 2
#1 65AE-01-0F		General 3 - Tactic 3
#1 65AF-01-13		General 3 - Tactic 4
#1 65B0-01-1E		General 3 - Tactic 5
#1 65B1-01-1A		General 3 - Tactic 6
#1 65B2-01-05		General 4 - Tactic 1
#1 65B3-01-0A		General 4 - Tactic 2
#1 65B4-01-0F		General 4 - Tactic 3
#1 65B5-01-13		General 4 - Tactic 4
#1 65B6-01-1E		General 4 - Tactic 5
#1 65B7-01-1A		General 4 - Tactic 6
#1 65B8-01-05		General 5 - Tactic 1
#1 65B9-01-0A		General 5 - Tactic 2
#1 65BA-01-0F		General 5 - Tactic 3
#1 65BB-01-13		General 5 - Tactic 4
#1 65BC-01-1E		General 5 - Tactic 5
#1 65BD-01-1A		General 5 - Tactic 6
#1 65BE-01-05		General 6 - Tactic 1
#1 65BF-01-0A		General 6 - Tactic 2
#1 65C0-01-0F		General 6 - Tactic 3
#1 65C1-01-13		General 6 - Tactic 4
#1 65C2-01-1E		General 6 - Tactic 5
#1 65C3-01-1A		General 6 - Tactic 6
#1 65C4-01-05		General 7 - Tactic 1
#1 65C5-01-0A		General 7 - Tactic 2
#1 65C6-01-0F		General 7 - Tactic 3
#1 65C7-01-13		General 7 - Tactic 4
#1 65C8-01-1E		General 7 - Tactic 4
#1 65C9-01-1A		General 7 - Tactic 6[/COLOR]

Infinite & Max Soldiers,
$C00F: E8 E8 E8 => 20 8C FE
3C01F E8 E8 E8 => 20 8C FE

$FE8C
3FE9C

E8 E8 E8
8A
48
A2 00
A9 9F
9D D0 60
9D 60 61
A9 86
9D D1 60
9D 61 61
A9 01
9D D2 60
9D 62 61
8A
C9 18 
D0 03
68
AA
60
18 69 04
AA
90 DA
60

Max Stats,
$EEF9: CA CA CA => 20 70 FF
3EF09 CA CA CA => 20 70 FF

$FF70:
3FF80
CA CA CA
8A
48
A2 00
A9 FF
9D 9C 61
9D A8 61
8A
C9 06 
D0 03
68
AA
60
18 69 01
AA
90 EA
60

Infinite Money and Food,

$EECB 20 FF C2 => 20 50 FE
3EEDB 20 FF C2 => 20 50 FE

$FE50:
3FE60

A9 7F
8D 76 60
8D 79 60
A9 96
8D 77 60
8D 7A 60
A9 98
8D 78 60
8D 7B 60
20 FF C2
60

All the Best Tactics,

$C07C 20 99 C0 => 20 00 FB
3C08C 20 99 C0 => 20 00 FB

$FB00:
3FB10

8A
48
A2 00
A9 05
9D A0 65
A9 0A
9D A1 65
A9 0F
9D A2 65
A9 13
9D A3 65
A9 1E
9D A4 65
A9 1A
9D A5 65
8A
C9 24 
D0 06
68
AA
20 99 C0
60
18 69 06
AA
90 D1
20 99 C0
60

Infinite & Max Tactic Points,

$EEDD 20 FC C0 => 20 37 FB
3EEED 20 FC C0 => 20 37 FB

$FB37:
3FB47

A9 9F
8D F8 61
8D FB 61
A9 86
8D F9 61
8D FC 61
A9 01
8D FA 61
8D FD 61
A9 00
8D FE 61
8D FF 61
8D 00 62
20 FC C0
60

I want to give my thanks to Pugsy and Ugetab. Without their help this hack would not exist .

Now to the question:

How can I recognize parts of any NES rom (I understand I must search addresses between $8000 and $FFFF) that are safe to replace with my own code injection?.
Destiny of an Emperor has not lots of FFs or 00s. The only part I found with dozens of them was not usefull because that part of the rom changes a lot in game. So using it crashed the game. So I had to arbitrary replace parts of the rom. I played the game past the middle of it and I can't found any bugs or crashes.

Thanks in advance n_n.

Whipon.

[scarface200729]

A good place for researching romhacking would be romhacking.net. Maybe they might have the answer to the question in their forums too.

[Whipon]

=)

I didnt' searched the forums at RHDN. I'll give it a try.
Anyway, I posted the question here, because all I know about rom hacking comes from the nice people here ñ_ñ. Just wanted to know wich areas of the rom are safe to replace with my own code.
Thank you.
Whipon.