Generating system names

Producing system names from twisted seeds and two-letter tokens

There are 256 systems in each of the eight galaxies in Elite, and each of those 2048 systems has a unique name, as shown in the system charts like this one from the start of the game:

System names aren't stored as plain text, as there simply isn't enough memory in Elite. Instead they are generated from the three 16-bit seeds for that system, and in the case of the selected system, those seeds live at QQ15. See the deep dive on galaxy and system seeds for more information about the seeds.

The process of printing the system name is done by the cpl routine. It works as follows, where s0, s1, s2 are the seeds for the system in question:

1. Check bit 6 of s0_lo. If it is set then we will generate four two-letter pairs for the name (8 characters in total), otherwise we will generate three pairs (6 characters).
2. Generate the first two letters by taking bits 0-4 of s2_hi. If this is zero, jump to the next step, otherwise we have a number in the range 1-31. Add 128 to get a number in the range 129-159, and convert this to a two-letter token (see variable QQ16 for the list of two-letter tokens).
3. Twist the seeds by calling TT54 and repeat the previous step, until we have processed three or four pairs, depending on step 1. The results of the final twist are ignored.

See the deep dive on twisting the system seeds for an explanation of the twisting process.

As the process above involves twisting the seeds three or four times, they will be changed, so we also need to back up the original seeds before starting the above process, and restore them afterwards. Also, the C flag is changed by the twisting process, and the C flag that results from the final twist feeds into the calculation of the system's star size on the Short-range Chart (with a clear C flag producing either a small or medium star, and a set C flag producing either a medium or large star).

Probably the best way to understand the process is to run through some examples, so let's do that now.

Two-letter system name: Ra
--------------------------

There is only one system in the whole game with a two-letter name: Ra in the first galaxy.

To generate the letter pairs, we start with the system's seeds and twist them twice to generate three letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%10000111	%10101010	%00001100	%00111000	%10000000	%01010011
1	%00001100	%00111000	%10000000	%01010011	%00010100	%00110101
2	%10000000	%01010011	%00010100	%00110101	%10100000	%11000000

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%0	-	Three pairs
-	s2_hi bits 0-4	%00000	0	Pair 1: Skip
1	s2_hi bits 0-4	%10100	128 + %10100 = 148	Pair 2: "RA"
2	s2_hi bits 0-4	%00000	0	Pair 3: Skip

Three-letter system name: Ara
-----------------------------

There are two system in the whole game with three-letter names: Ara in the first galaxy and Rea in the third galaxy. Let's look at Ara here.

To generate the letter pairs, we start with the system's seeds and twist them twice to generate three letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%00101000	%00000000	%00011100	%11000000	%01001111	%01001101
1	%00011100	%11000000	%01001111	%01001101	%10010100	%00001101
2	%01001111	%01001101	%10010100	%00001101	%00000000	%00011010

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%0	-	Three pairs
-	s2_hi bits 0-4	%01111	128 + %01111 = 143	Pair 1: "A"
1	s2_hi bits 0-4	%10100	128 + %10100 = 148	Pair 2: "RA"
2	s2_hi bits 0-4	%00000	0	Pair 3: Skip

Four-letter system name: Lave
-----------------------------

Lave is the iconic starting system in Elite, so let's see how this name is generated.

To generate the letter pairs, we start with the system's seeds and twist them twice to generate three letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%10101101	%00111000	%00010100	%10011100	%00010101	%00011101
1	%00010100	%10011100	%00010101	%00011101	%11010110	%11110001
2	%00010101	%00011101	%11010110	%11110001	%00000000	%10101010

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%0	-	Three pairs
-	s2_hi bits 0-4	%10101	128 + %10101 = 149	Pair 1: "LA"
1	s2_hi bits 0-4	%10110	128 + %10110 = 150	Pair 2: "VE"
2	s2_hi bits 0-4	%00000	0	Pair 3: Skip

Five-letter system name: Arexe
------------------------------

Arexe is a key system in the Constrictor mission, as that's where the stolen ship jumps from the first to the second galaxy. The clue appears when you dock at Reesdice:

A STRANGE LOOKING SHIP LEFT HERE A WHILE BACK. LOOKED BOUND FOR AREXE.

To generate the letter pairs, we start with the system's seeds and twist them three times to generate four letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%01011001	%01111010	%10100100	%11110000	%11101111	%10110011
1	%10100100	%11110000	%11101111	%10110011	%11101110	%00011101
2	%11101111	%10110011	%11101110	%00011101	%10000010	%11000000
3	%11101110	%00011101	%10000010	%11000000	%01100000	%10010000

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%1	-	Four pairs
-	s2_hi bits 0-4	%01111	128 + %01111 = 143	Pair 1: "A"
1	s2_hi bits 0-4	%01110	128 + %01110 = 142	Pair 2: "RE"
2	s2_hi bits 0-4	%00010	128 + %00010 = 130	Pair 3: "XE"
3	s2_hi bits 0-4	%00000	0	Pair 4: Skip

Six-letter system name: Errius
------------------------------

Also a key player in the Constrictor mission, Errius is the first clue we get when we arrive in the second galaxy - and its hint is certainly the most memorable:

GET YOUR IRON ASS OVER TO ERRIUS.

To generate the letter pairs, we start with the system's seeds and twist them twice to generate three letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%10010101	%10000000	%10111000	%10100000	%01110000	%11011010
1	%10111000	%10100000	%01110000	%11011010	%10111110	%11111010
2	%01110000	%11011010	%10111110	%11111010	%11101000	%01110100

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%0	-	Three pairs
-	s2_hi bits 0-4	%10000	128 + %10000 = 144	Pair 1: "ER"
1	s2_hi bits 0-4	%11110	128 + %11110 = 158	Pair 2: "RI"
2	s2_hi bits 0-4	%01000	128 + %01000 = 136	Pair 3: "US"

Seven-letter system name: Geinona
---------------------------------

Let's look at a seven-letter name now - and how about picking the 42nd system in the first galaxy, as that's an auspicious number?

To generate the letter pairs, we start with the system's seeds and twist them three times to generate four letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%10011001	%11000000	%10001111	%00001000	%01100011	%10111101
1	%10001111	%00001000	%01100011	%10111101	%10001100	%10000101
2	%01100011	%10111101	%10001100	%10000101	%01111111	%01001010
3	%10001100	%10000101	%01111111	%01001010	%01101111	%10001100

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%1	-	Four pairs
-	s2_hi bits 0-4	%00011	128 + %00011 = 131	Pair 1: "GE"
1	s2_hi bits 0-4	%01100	128 + %01100 = 140	Pair 2: "IN"
2	s2_hi bits 0-4	%11111	128 + %11111 = 159	Pair 3: "ON"
3	s2_hi bits 0-4	%01111	128 + %01111 = 143	Pair 4: "A"

Eight-letter system name: Tibedied
----------------------------------

Tibedied is the first system in the first galaxy, so these are the only seeds that are hard-coded into the game. They are embedded into the default commander at NA%, in bytes #3 to #8.

To generate the letter pairs, we start with the system's seeds and twist them three times to generate four letter pairs. The twists are as follows:

Twist	s0_hi	s0_lo	s1_hi	s1_lo	s2_hi	s2_lo
-	%01011010	%01001010	%00000010	%01001000	%10110111	%01010011
1	%00000010	%01001000	%10110111	%01010011	%00010011	%11100101
2	%10110111	%01010011	%00010011	%11100101	%11001101	%10000000
3	%00010011	%11100101	%11001101	%10000000	%10011000	%10111000

And this gives us the following result:

Twist	Seed bits	Bits	Calculation	Result
-	s0_lo bit 6	%1	-	Four pairs
-	s2_hi bits 0-4	%10111	128 + %10111 = 151	Pair 1: "TI"
1	s2_hi bits 0-4	%10011	128 + %10011 = 147	Pair 2: "BI"
2	s2_hi bits 0-4	%01101	128 + %01101 = 141	Pair 3: "DI"
3	s2_hi bits 0-4	%11000	128 + %11000 = 152	Pair 4: "ED"