Source Code
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These source-code files were transcribed from scans made from Don Eyles's personal
copy of BURST120 (SUNBURST 120). They were scanned at archive.org's Boston
facility, and the scanning was sponsored by Mike Stewart. The code was transcribed
from these scans by a team of volunteers who are referenced in the program
comments. Comments from the original source code are in ALL-CAPS, whereas
comments added later in transcription are in Mixed-Case. In some cases, where
similar code blocks exist in previously-transcribed AGC programs (primarily
Luminary 99, from Apollo 11) those code blocks were used as a starting point and
then corrected to agree with the BURST120 scans. The full scans are available
at the Virtual AGC
project's collection at archive.org, while more-convenient reduced-size (but reduced-quality)
images are available at
the main Virtual AGC website. Report any errors noted by creating an
issue report at the Virtual AGC
project's GitHub repository. Notations on the program listing read, in part:YUL SYSTEM FOR AGC: REVISION 0 OF PROGRAM BURST120 BY NASA 2021106-031 DEC 7, 1967 THIS LISTING IS A COPY OF A VERSION OF THE PROGRAM INTENDED FOR USE IN THE ON-BOARD PRIMARY GUIDANCE COMPUTER IN THE UNMANNED FLIGHT OF APOLLO LUNAR MODULE 1 --- THE AS206 MISSION.Note that the date is the date of the printout, not the date of the program revision. |
044037,000002: ## Copyright: Public domain.
044038,000003: ## Filename: SINGLE_PRECISION_SUBROUTINES.agc
044039,000004: ## Purpose: A module for revision 0 of BURST120 (Sunburst). It
044040,000005: ## is part of the source code for the Lunar Module's
044041,000006: ## (LM) Apollo Guidance Computer (AGC) for Apollo 5.
044042,000007: ## Assembler: yaYUL
044043,000008: ## Contact: Ron Burkey <info@sandroid.org>.
044044,000009: ## Website: www.ibiblio.org/apollo/index.html
044045,000010: ## Mod history: 2016-09-30 RSB Created draft version.
044046,000011: ## 2016-10-19 RSB Transcribed ... I think it's identical to the
044047,000012: ## Aurora 12 version.
044048,000013: ## 2016-12-06 RSB Comments proofed using octopus/ProoferComments,
044049,000014: ## no changes made.
044050,000015:
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Page 1046 |
044052,000017: 5354 BLOCK 02
044053,000018: # SINGLE PRECISION SINE AND COSINE
044054,000019:
044055,000020: 5354 67746 SPCOS AD HALF # ARGUMENTS SCALED AT PI
044056,000021: 5355 55130 SPSIN TS TEMK
044057,000022: 5356 15360 TCF SPT
044058,000023: 5357 41130 CS TEMK
044059,000024: 5360 60000 SPT DOUBLE
044060,000025: 5361 55130 TS TEMK
044061,000026: 5362 15373 TCF POLLEY
044062,000027: 5363 57130 XCH TEMK
044063,000028: 5364 51130 INDEX TEMK
044064,000029: 5365 67744 AD LIMITS
044065,000030: 5366 40000 COM
044066,000031: 5367 61130 AD TEMK
044067,000032: 5370 55130 TS TEMK
044068,000033: 5371 15373 TCF POLLEY
044069,000034: 5372 15411 TCF ARG90
044070,000035: 5373 00006 POLLEY EXTEND
044071,000036: 5374 71130 MP TEMK
044072,000037: 5375 55131 TS SQ
044073,000038: 5376 00006 EXTEND
044074,000039: 5377 75416 MP C5/2
044075,000040: 5400 65415 AD C3/2
044076,000041: 5401 00006 EXTEND
044077,000042: 5402 71131 MP SQ
044078,000043: 5403 65414 AD C1/2
044079,000044: 5404 00006 EXTEND
044080,000045: 5405 71130 MP TEMK
044081,000046: 5406 20001 DDOUBL
044082,000047: 5407 55130 TS TEMK
044083,000048: 5410 00002 TC Q
044084,000049: 5411 50000 ARG90 INDEX A
044085,000050: 5412 47744 CS LIMITS
044086,000051: 5413 00002 TC Q # RESULT SCALED AT 1
044087,000052: 5414 31103 C1/2 DEC .7853134
044088,000053: 5415 65552 C3/2 DEC -.3216146
044089,000054: 5416 01124 C5/2 DEC .0363551
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044091,000056: # ENTER WITH ARGUMENT IN A, EXIT WITH ROOT IN A. IF GIVEN A NEGATIVE ARGUMENT, THE RETURN SKIPS WITH CCS RESULT.
044092,000057: # MINUS ZERO RETURNS LIKE PLUS ZERO.
044093,000058: # MAXIMUM ERROR IN ANSWER IS NO GREATER THAN 2 BITS.
044094,000059: # INTERRUPT PROGRAMS USING SPROOT MUST SAVE AND RESTORE SR.
044095,000060:
044096,000061:
044097,000062:
044098,000063: 5417 55132 SPROOT TS SQRARG # ENTER WITH C(A) = Y
044099,000064: 5420 10000 CCS A
044100,000065: 5421 15425 TCF POSARG # IF PNZ, CONTINUE
044101,000066: 5422 00002 TC Q # RETURN WITH 0 FOR +0
044102,000067: 5423 24002 INCR Q
044103,000068: 5424 00002 TC Q # RETURN WITH 0 FOR -0
044104,000069:
044105,000070: 5425 00006 POSARG EXTEND
044106,000071: 5426 23131 QXCH ROOTRET # WILL BE CALLING SPROOT1
044107,000072: 5427 65504 AD 63/64+1 # B(A) = Y - 1
044108,000073: 5430 54000 OVSK
044109,000074: 5431 15473 TCF SPROOT2
044110,000075: 5432 57132 XCH SQRARG # ARG JUGGLING
044111,000076:
044112,000077: 5433 55132 SPROOT3 TS SQRARG
044113,000078: 5434 54021 TS SR # C(A) = Y
044114,000079: 5435 56021 XCH SR # (LOSE 1 BIT)
044115,000080: 5436 55130 TS HALFY # HALFY = Y/2
044116,000081: 5437 65502 AD -1/8 # FORM Y/2 - 1/8
044117,000082: 5440 10000 CCS A # TEST FOR FIRST GUESS
044118,000083: 5441 65503 AD 5/8+1 # Y .G. 1/4, X = Y/2 + 1/2
044119,000084: 5442 05447 TC HIGUESS # +0 IMPOSSIBLE FROM ADDITION
044120,000085: 5443 15444 NOOP # Y .LE. 1/4, X/2 = Y + 1/16
044121,000086: 5444 37751 CAF BIT11 # 1/16
044122,000087: 5445 61132 AD SQRARG # SQRARG = Y
044123,000088: 5446 60000 DOUBLE # X FROM X/2
044124,000089: 5447 05462 HIGUESS TC SPROOT1
044125,000090: 5450 05462 TC SPROOT1 # ITERATE TWICE
044126,000091: 5451 57131 XCH ROOTRET # SAVE ANSWER AND GET Q
044127,000092: 5452 10000 CCS A
044128,000093: 5453 57131 XCH ROOTRET # NO SHIFT NEEDED
044129,000094: 5454 05460 TC ROOTBCK
044130,000095: 5455 57131 XCH ROOTRET # Q NEG, SHIFT RIGHT THREE
044131,000096: 5456 00006 EXTEND
044132,000097: 5457 77750 MP BIT12 # EXP -3
044133,000098: 5460 51131 ROOTBCK INDEX ROOTRET # ROOTRET = Q - 1
044134,000099: 5461 00001 TC 1 # RETURN, C(A) = SQRT(Y)
044135,000100:
044136,000101: 5462 56021 SPROOT1 XCH SR # SR = X/2
044137,000102: 5463 41130 CS HALFY # NEWTON ITER X = X/2 + (Y/2 / X/2) / 2
044138,000103: 5464 22007 ZL
044139,000104: 5465 00006 EXTEND
044140,000105: 5466 10021 DV SR # C(SR) = X/2 DV DOES NOT EDIT
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044142,000107: 5467 56021 XCH SR
044143,000108: 5470 00006 EXTEND
044144,000109: 5471 60021 SU SR
044145,000110: 5472 00002 TC Q # C(A) = X (NEXT)
044146,000111:
044147,000112: 5473 41131 SPROOT2 CS ROOTRET # SET RETURN Q NEG, AS FLAG
044148,000113: 5474 55131 TS ROOTRET
044149,000114: 5475 37755 CAF BIT7 # SHIFT FOR SIGNIFCANCE
044150,000115: 5476 00006 EXTEND
044151,000116: 5477 71132 MP SQRARG
044152,000117: 5500 30001 CA L # B(A) = 0
044153,000118: 5501 05433 TC SPROOT3
044154,000119:
044155,000120: 5502 73777 -1/8 OCTAL 73777
044156,000121: 5503 24001 5/8+1 OCTAL 24001
044157,000122: 5504 37401 63/64+1 OCTAL 37401
044158,000123:
End of include-file SINGLE_PRECISION_SUBROUTINES.agc. Parent file is MAIN.agc