This code appears in the following versions (click to see it in the source code):
Code variations between these versions are shown below.
Name: TT25 Type: Subroutine Category: Universe
.TT25Deep dive: Generating system data Galaxy and system seeds
Other entry points: TT72 Used by TT70 to re-enter the routine after displaying "MAINLY" for the economy type
In the 6502SP version, you can send the Data on System screen to the printer by pressing CTRL-f6.
Tap on a block to expand it, and tap it again to revert.
JSR TTX69 \ Print a paragraph break and set Sentence Case
The cassette version doesn't show extended system descriptions in the Data on System screen, and neither does the disc version when we are in flight, so both of these show the information one line lower on-screen than in the other versions.
This variation is blank in the Disc (docked), 6502 Second Processor and Master versions.
INC YC \ Move the text cursor down one more line
JSR TT146 \ If the distance to this system is non-zero, print \ "DISTANCE", then the distance, "LIGHT YEARS" and a \ paragraph break, otherwise just move the cursor down \ a line LDA #194 \ Print recursive token 34 ("ECONOMY") followed by JSR TT68 \ a colon LDA QQ3 \ The system economy is determined by the value in QQ3, \ so fetch it into A. First we work out the system's \ prosperity as follows: \ \ QQ3 = 0 or 5 = %000 or %101 = Rich \ QQ3 = 1 or 6 = %001 or %110 = Average \ QQ3 = 2 or 7 = %010 or %111 = Poor \ QQ3 = 3 or 4 = %011 or %100 = Mainly CLC \ If (QQ3 + 1) >> 1 = %10, i.e. if QQ3 = %011 or %100 ADC #1 \ (3 or 4), then call TT70, which prints "MAINLY " and LSR A \ jumps down to TT72 to print the type of economy CMP #%00000010 BEQ TT70 LDA QQ3 \ If (QQ3 + 1) >> 1 < %10, i.e. if QQ3 = %000, %001 or BCC TT71 \ %010 (0, 1 or 2), then jump to TT71 with A set to the \ original value of QQ3 SBC #5 \ Here QQ3 = %101, %110 or %111 (5, 6 or 7), so subtract CLC \ 5 to bring it down to 0, 1 or 2 (the C flag is already \ set so the SBC will be correct) .TT71 ADC #170 \ A is now 0, 1 or 2, so print recursive token 10 + A. JSR TT27 \ This means that: \ \ QQ3 = 0 or 5 prints token 10 ("RICH ") \ QQ3 = 1 or 6 prints token 11 ("AVERAGE ") \ QQ3 = 2 or 7 prints token 12 ("POOR ") .TT72 LDA QQ3 \ Now to work out the type of economy, which is LSR A \ determined by bit 2 of QQ3, as follows: LSR A \ \ QQ3 bit 2 = 0 = Industrial \ QQ3 bit 2 = 1 = Agricultural \ \ So we fetch QQ3 into A and set A = bit 2 of QQ3 using \ two right shifts (which will work as QQ3 is only a \ 3-bit number) CLC \ Print recursive token 8 + A, followed by a paragraph ADC #168 \ break and Sentence Case, so: JSR TT60 \ \ QQ3 bit 2 = 0 prints token 8 ("INDUSTRIAL") \ QQ3 bit 2 = 1 prints token 9 ("AGRICULTURAL") LDA #162 \ Print recursive token 2 ("GOVERNMENT") followed by JSR TT68 \ a colon LDA QQ4 \ The system's government is determined by the value in \ QQ4, so fetch it into A CLC \ Print recursive token 17 + A, followed by a paragraph ADC #177 \ break and Sentence Case, so: JSR TT60 \ \ QQ4 = 0 prints token 17 ("ANARCHY") \ QQ4 = 1 prints token 18 ("FEUDAL") \ QQ4 = 2 prints token 19 ("MULTI-GOVERNMENT") \ QQ4 = 3 prints token 20 ("DICTATORSHIP") \ QQ4 = 4 prints token 21 ("COMMUNIST") \ QQ4 = 5 prints token 22 ("CONFEDERACY") \ QQ4 = 6 prints token 23 ("DEMOCRACY") \ QQ4 = 7 prints token 24 ("CORPORATE STATE") LDA #196 \ Print recursive token 36 ("TECH.LEVEL") followed by a JSR TT68 \ colon LDX QQ5 \ Fetch the tech level from QQ5 and increment it, as it INX \ is stored in the range 0-14 but the displayed range \ should be 1-15 CLC \ Call pr2 to print the technology level as a 3-digit JSR pr2 \ number without a decimal point (by clearing the C \ flag) JSR TTX69 \ Print a paragraph break and set Sentence Case LDA #192 \ Print recursive token 32 ("POPULATION") followed by a JSR TT68 \ colon SEC \ Call pr2 to print the population as a 3-digit number LDX QQ6 \ with a decimal point (by setting the C flag), so the JSR pr2 \ number printed will be population / 10 LDA #198 \ Print recursive token 38 (" BILLION"), followed by a JSR TT60 \ paragraph break and Sentence Case LDA #'(' \ Print an opening bracket JSR TT27 LDA QQ15+4 \ Now to calculate the species, so first check bit 7 of BMI TT75 \ s2_lo, and if it is set, jump to TT75 as this is an \ alien species LDA #188 \ Bit 7 of s2_lo is clear, so print recursive token 28 JSR TT27 \ ("HUMAN COLONIAL") JMP TT76 \ Jump to TT76 to print "S)" and a paragraph break, so \ the whole species string is "(HUMAN COLONIALS)" .TT75 LDA QQ15+5 \ This is an alien species, and we start with the first LSR A \ adjective, so fetch bits 2-7 of s2_hi into A and push LSR A \ onto the stack so we can use this later PHA AND #%00000111 \ Set A = bits 0-2 of A (so that's bits 2-4 of s2_hi) CMP #3 \ If A >= 3, jump to TT205 to skip the first adjective, BCS TT205 ADC #227 \ Otherwise A = 0, 1 or 2, so print recursive token JSR spc \ 67 + A, followed by a space, so: \ \ A = 0 prints token 67 ("LARGE") and a space \ A = 1 prints token 68 ("FIERCE") and a space \ A = 2 prints token 69 ("SMALL") and a space .TT205 PLA \ Now for the second adjective, so restore A to bits LSR A \ 2-7 of s2_hi, and throw away bits 2-4 to leave LSR A \ A = bits 5-7 of s2_hi LSR A CMP #6 \ If A >= 6, jump to TT206 to skip the second adjective BCS TT206 ADC #230 \ Otherwise A = 0 to 5, so print recursive token JSR spc \ 70 + A, followed by a space, so: \ \ A = 0 prints token 70 ("GREEN") and a space \ A = 1 prints token 71 ("RED") and a space \ A = 2 prints token 72 ("YELLOW") and a space \ A = 3 prints token 73 ("BLUE") and a space \ A = 4 prints token 74 ("BLACK") and a space \ A = 5 prints token 75 ("HARMLESS") and a space .TT206 LDA QQ15+3 \ Now for the third adjective, so EOR the high bytes of EOR QQ15+1 \ s0 and s1 and extract bits 0-2 of the result: AND #%00000111 \ STA QQ19 \ A = (s0_hi EOR s1_hi) AND %111 \ \ storing the result in QQ19 so we can use it later CMP #6 \ If A >= 6, jump to TT207 to skip the third adjective BCS TT207 ADC #236 \ Otherwise A = 0 to 5, so print recursive token JSR spc \ 76 + A, followed by a space, so: \ \ A = 0 prints token 76 ("SLIMY") and a space \ A = 1 prints token 77 ("BUG-EYED") and a space \ A = 2 prints token 78 ("HORNED") and a space \ A = 3 prints token 79 ("BONY") and a space \ A = 4 prints token 80 ("FAT") and a space \ A = 5 prints token 81 ("FURRY") and a space .TT207 LDA QQ15+5 \ Now for the actual species, so take bits 0-1 of AND #%00000011 \ s2_hi, add this to the value of A that we used for CLC \ the third adjective, and take bits 0-2 of the result ADC QQ19 AND #%00000111 ADC #242 \ A = 0 to 7, so print recursive token 82 + A, so: JSR TT27 \ \ A = 0 prints token 82 ("RODENT") \ A = 1 prints token 83 ("FROG") \ A = 2 prints token 84 ("LIZARD") \ A = 3 prints token 85 ("LOBSTER") \ A = 4 prints token 86 ("BIRD") \ A = 5 prints token 87 ("HUMANOID") \ A = 6 prints token 88 ("FELINE") \ A = 7 prints token 89 ("INSECT") .TT76 LDA #'S' \ Print an "S" to pluralise the species JSR TT27 LDA #')' \ And finally, print a closing bracket, followed by a JSR TT60 \ paragraph break and Sentence Case, to end the species \ section LDA #193 \ Print recursive token 33 ("GROSS PRODUCTIVITY"), JSR TT68 \ followed by a colon LDX QQ7 \ Fetch the 16-bit productivity value from QQ7 into LDY QQ7+1 \ (Y X) JSR pr6 \ Print (Y X) to 5 digits with no decimal point JSR TT162 \ Print a space
LDA #'M' \ Print "M" JSR TT27 LDA #226 \ Print recursive token 66 (" CR"), followed by a JSR TT60 \ paragraph break and Sentence Case LDA #250 \ Print recursive token 90 ("AVERAGE RADIUS"), followed JSR TT68 \ by a colon \ The average radius is calculated like this: \ \ ((s2_hi AND %1111) + 11) * 256 + s1_hi \ \ or, in terms of memory locations: \ \ ((QQ15+5 AND %1111) + 11) * 256 + QQ15+3 \ \ Because the multiplication is by 256, this is the \ same as saying a 16-bit number, with high byte: \ \ (QQ15+5 AND %1111) + 11 \ \ and low byte: \ \ QQ15+3 \ \ so we can set this up in (Y X) and call the pr5 \ routine to print it out LDA QQ15+5 \ Set A = QQ15+5 LDX QQ15+3 \ Set X = QQ15+3 AND #%00001111 \ Set Y = (A AND %1111) + 11 CLC ADC #11 TAY JSR pr5 \ Print (Y X) to 5 digits, not including a decimal \ point, as the C flag will be clear (as the maximum \ radius will always fit into 16 bits) JSR TT162 \ Print a space
Extended system descriptions are shown in the enhanced versions, though in the disc version they are only shown when docked, as the PDESC routine isn't present in the flight code due to memory restrictions.
This variation is blank in the Cassette, Disc (flight) and Electron versions.
JSR TTX69 \ Print a paragraph break and set Sentence Case \ By this point, ZZ contains the current system number \ which PDESC requires. It gets put there in the TT102 \ routine, which calls TT111 to populate ZZ before \ calling TT25 (this routine) JMP PDESC \ Jump to PDESC to print the system's extended \ description, returning from the subroutine using a \ tail call