K240 Save Game

Disassembly of K240 v2.000 reveals a series of nine calls to the dos.library Write() function, beginning at position $03414 in the main game executable. It's reasonable to conclude that these form K240's save game function. All but one section are given explicit sizes except PART1, whose size can be surmised knowing the save game filesize of 151,850 bytes.

Section	Start (bytes)	Size (bytes)	Content	Referenced
PART0	0	18	Game filename and alien	Directly
PART1	18	30	Alien data	Directly
PART2	48	55810	??	Directly
PART3	55858	37800	Ships	By pointer
PART4	93658	33600	Buildings	By pointer
PART5	127258	18000	Asteroid and colony data	By pointer
PART6	145258	1920	??	By pointer
PART7	147178	2336	??	By pointer
PART8	149514	2336	??	By pointer
END	151850	-	-	-

Save game format

Part 0

Start (bytes)	Size (bytes)	Content
0	16	Game filename (string)
17	2	Current alien number

The last two bytes are probably the alien number, beginning with Kll-Kp-Qua as 01. An alien number of 00 means the game was saved between games.

Part 1

30 bytes long. It appears to be part of the alien data file a1data4 to a6data4, the thirty bytes after the first four bytes of the file. Disassembly suggests the following format.

Position	Type	Default value
$20300	Long	$20a68 (ptr)
$20304	Word	$0001
$20306	Word	$003c
$20308	Word	$0000
$2030a	Word	$0046
$2030c	Word	$00c8
$2030e	Word	$0019
$20310	Word	$0014
$20312	Word	$0000
$20314	Word	$0000
$20316	Word	$0002
$20318	Word	$0004
$2031a	Word	$0006
$2031c	Word	$0010
$2031e	Word	$0028
$20320	Byte	$08
$20321	Byte	$00

Part 2

A complex, 55,810-byte structure containing over a hundred game variables. The default values are stored in the game executable, beginning at position $20a8c. Disassembly using IRA gives 186 labels in the area used for this part of the save game.

This structure is currently poorly understood.

Start (bytes)	Size (bytes, decimal)	Content
0	80	20 longs ??
80	160	Ore prices
240	112	??
352	53,856	Asteroid maps
54,208	1,602	??

There are 24 asteroid maps of 2,244 bytes, or 32 lines of 68 byte width.

Part 3

This 37,800 byte section holds data on 700 ships, storing 54 bytes per ship. This includes alien ships. What happens when more than 700 ships are built is untested.

This data structure is detailed in Ships: Current ship data.

Part 4

A 33,600 byte data structure. It stores the current building data for 24 asteroids, for 100 buildings per asteroid, storing 14 bytes per building.

The data structure is detailed in K240 buildings, "Current building data".

Part 5

A 18,000 byte structure which stores asteroid and colony data for 24 asteroids, storing 750 bytes per asteroid. Includes alien asteroids.

The data structure is only partially decoded so far.

Datatype	Start (bytes, decimal)	Description
15-17 bytes?	40	Asteroid name
10 words	62	Amount of each ore on asteroid
11 words	100	Number of each missile at asteroid
Word	170	Number of spy satellites in asteroid
Word	684	Current population
3 words	694	Power production, usage, and surplus
3 words	700	Air production, usage, and surplus
3 words	706	Food production, usage, and surplus
3 words	712	Water production, usage, and surplus

Part 6

Unknown 1,920 byte structure. If it stores data on a per-asteroid basis, it stores 80 bytes per asteroid.

Part 7

Unknown 2,336 byte structure.

Part 8

Unknown 2,336 byte structure.

Save game code snippet

This code snippet is taken from a disassembly of K240 v2.00 using IRA, and begins at hexadecimal position $03414.

LAB_010D:
    MOVE.L    0(A0,D0.W),D1    
    MOVE.L    D1,LAB_0B3D    ; file to open
    MOVE.L    #$000003ee,D2  ; mode (write)
    JSR       -30(A6)        ; dos.library Open()
    MOVE.L    D0,SECSTRT_1   ; store file pointer
    BEQ.W     LAB_010F       

    MOVE.L    SECSTRT_1,D1   ; File pointer
    MOVE.L    #LAB_0B59,D2   ; Source buffer
    MOVEQ     #18,D3         ; length (18 bytes)
    JSR       -48(A6)        ; dos.library Write()
    TST.L     D0             ; Check if file write was successful
    BMI.W     LAB_0111       ; If not, close and delete the file

    MOVE.L    SECSTRT_1,D1   ; File pointer
    MOVE.L    #LAB_0C7C,D2   ; Source buffer
    MOVE.L    #LAB_0C8C,D3   ; length (LAB_0C8C bytes)
    SUB.L     D2,D3          
    JSR       -48(A6)        ; dos.library Write()
    TST.L     D0             ; Check if file write was successful
    BMI.W     LAB_0111       ; If not, close and delete the file

    MOVE.L    SECSTRT_1,D1   ; file pointer
    MOVE.L    #LAB_0C99,D2   ; buffer
    MOVE.L    #$0000da02,D3  ; length (55,810 bytes)
    JSR       -48(A6)        ; dos.library write
...