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Further reading □ Overview □ About Ferranti □ Brochure □ Architecture □ Architecture □ 1-Level Storage □ Words □ Instructions □ Order Code □ Animated □ Hardware □ Fixed Store □ Supervisor □ Overview □ Scheduler □ Core Memory □ Atlas Card □ Atlas Console □ Console Details □ Chilton □ Chilton Atlas □ Downstairs □ Manchester □ Manchester Atlas □ London □ London Atlas □ London Software □ Atlas II □ Atlas 2 Brochure □ Titan Autocode □ Cambridge Atlas □ Closure □ Atlas Closure
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⟶ ACL ⟶ Technology ⟶ ATLAS
⟶ ACL ⟶ Technology ⟶ ATLAS
ACL ACD C&A INF CCD CISD Archives
Further reading ⇓

□ Overview □ About Ferranti □ Brochure
Architecture
□ Architecture □ 1-Level Storage □ Words □ Instructions □ Order Code □ Animated
Hardware
□ Fixed Store □ Supervisor □ Overview □ Scheduler □ Core Memory □ Atlas Card □ Atlas Console □ Console Details
Chilton
□ Chilton Atlas □ Downstairs
Manchester
□ Manchester Atlas
London
□ London Atlas □ London Software
Atlas II
□ Atlas 2 Brochure □ Titan Autocode □ Cambridge Atlas
Closure
□ Atlas Closure

Animated Order Code

The Bible

The following SVG animation gives a flavour of the Atlas Order Code

Basic B-Register Arithmetic 100 ba'= s - ba 101 ba'= s 102 ba'= ba - s 103 ba'= - s 104 ba'= ba + s 110 s'= s - ba 111 s'= - ba 112 s'= ba - s 113 s'= ba 114 s'= ba + s 120 ba'= n - ba 121 ba'= n 122 ba'= ba - n 123 ba'= - n 124 ba'= ba + n Note: The B-Carry Digit is set by instructions ending 0, 2 or 4. Logical B-Register Operations 107 ba'= ba & s 117 s'= ba & s 127 ba'= ba & n 164* ba'= ba + (bm & n) 165* ba'= bm & n 106 ba'= ba a s 116 s'= ba a s 126 ba'= ba a n 147 ba'= ba b s 167 ba'= ba b n * If Bm is B0, bm & n = n . Note: 164 sets the B-Carry Digit. Test Instructions ba' = n if :- 210 bm is odd (i.e. bit 23 = 1) 211 bm is even (i.e. bit 23 = 0) 214 bm = 0 215 bm ≠ 0 216 bm ≥ 0 217 bm < 0 224 bt = 0 225 bt ≠ 0 226 bt ≥ 0 227 bt < 0 234 ax = 0 235 ax ≠ 0 236 ax ≥ 0 237 ax < 0 Test and Count Codes 200 If bm ≠ 0, ba' = n and bm' = bm + 0.4 201 If bm ≠ 0, ba' = n and bm' = bm + 1.0 202 If bm ≠ 0, ba' = n and bm' = bm - 0.4 203 If bm ≠ 0, ba' = n and bm' = bm - 1.0 220 If bt ≠ 0, ba' = n and bm' = bm + 0.4 221 If bt ≠ 0, ba' = n and bm' = bm + 1.0 222 If bt ≠ 0, ba' = n and bm' = bm - 0.4 233 If bt ≠ 0, ba' = n and bm' = bm - 1.0 Accumulator Transfer Instructions 324 am' = s Q 325 am' = - s QE 334 am' = s 335 am' = - s AO 314 am' = s NL 315 am' = - s NL AO 367 am' = | s | QE 344 l ' = sx , am' = am 345 l ' = sx , m' = sign of s ay ' = ay 346 s ' = am , a ' = 0 356 s ' = am , a ' = a 347 s ' = al , l ' = 0 357 s ' = al , a ' = a Other Accumulator Instructions 364 ax ' = 8 ax , ay' = ay 365 ax ' = ax / 8 , ay' = ay 310 a ' = a + s if ay ≤ sy QE NL (otherwise am ' = am + s, l spoiled) 311 a ' = a - s if ay ≤ sy QE NL (otherwise am ' = am - s, l spoiled) 352 a ' = am × s , sign l ' = sign m ' E AO 353 a ' = - am × s , sign l ' = sign m ' E AO 376 al ' = a / | s | if a ≥ 0 E DO ay ' = exponent of quotient, m ' = "remainder" 377 al ' = | am | / | s | E DO ay ' = exponent of quotient, m ' = "remainder" 361 am ' = a RE NL 354 am ' = a rounded by adding AO NL 355 a ' = al × 8 -13 Q 366 a ' = | am | QE B-register Extracodes 1300 ba ' = int. pt. of s am ' = frac. pt. of s 1301 ba ' = int. pt. of am am ' = frac. pt. of am 1302 ba ' = ba × n 1303 ba ' = - ba × n 1304 ba ' = ba / n b 97 ' = remainder } 21-bit integers 1312 ba ' = ba × n 1313 ba ' = - ba × n 1314 ba ' = ba / n b 97 ' = remainder } 24-bit integers Shifts 1340 ba ' = ba × 2 -n arithmetic 1341 ba ' = ba × 2 n arithmetic 1342 ba ' = ba × 2 -n circular 1343 ba ' = ba × 2 n circular 1344 ba ' = ba × 2 -n logical 1345 ba ' = ba × 2 n logical Trigonometric Functions 1730 am ' = sin s 1731 am ' = sin aq 1732 am ' = cos s 1733 am ' = cos aq 1734 am ' = tan s 1735 am ' = tan aq 1720 am ' = arcsin s ( - π /2 ≤ am' ≤ π /2 ) 1721 am ' = arcsin aq ( - π /2 ≤ am' ≤ π /2 ) 1722 am ' = arccos s ( 0 ≤ am' ≤ π ) 1723 am ' = arccos aq ( 0 ≤ am' ≤ π ) 1724 am ' = arctan s ( - π /2 < am' < π /2 ) 1725 am ' = arctan aq ( - π /2 < am' < π /2 ) 1726 am ' = arctan aq/s ( - π ≤ am' ≤ π ) Arithmetic Extracode Functions 1700 am ' = log s 1701 am ' = log aq 1702 am ' = exp s 1703 am ' = exp aq 1704 a ' = integral part of s 1705 a ' = integral part of a 1706 a ' = sign of s 1707 a ' = sign of a 1710 am ' = r s 1711 am ' = r aq 1712 am ' = t aq 2 + s 2 1760 am ' = am 2 1713 am ' = aq s ( aq ≥ 0 ) 1714 am ' = 1 / s DO 1715 am ' = 1 / am DO 1757 am ' = s / am DO 1774 am ' = am / s QRE 1775 am ' = aq / s 1776 s ' = quotient Q am ' = remainder Q if used immediately after 1574, 1575, 1774, 1775. 1756 s ' = am , am ' = s 1766 am ' = | s | AO 17667 am ' = | am | AO Double Length Arithmetic 1500 a' = a + s: 1501 a' = a - s: 1502 a' = - a + s: 1504 a' = s: 1505 a' = - s: 1542 a' = a × s: 1543 a' = - a × s: 1556 s:' = a 1565 a' = - a 1566 a' = | a | 1567 a' = | s: | 1576 a' = a / s: Standardised, Rounded Arithmetic 320 am' = am + s QRE 321 am' = am - s QRE 322 am' = - am + s QRE 360 am' = a NL, QRE 362 am' = am × s QRE 363 am' = - am × s QRE 374 am' = am / s QRE DO Standardised, Unrounded Arithmetic 300 a' = am + s QE 301 a' = am - s QE 302 a' = - am + s QE 340 a' = a NL, QE 342 a' = am × s QE 343 a' = - am × s QE Unstandardised Arithmetic 330 a' = am + s AO 331 a' = am - s AO 332 a' = - am + s AO 341 a' = a NL, E 372 a' = am × s EAO 373 a' = - am × s EAO 375 al' = am / | s | m' = remainder E Set B-test 150 bt' = s - ba 152 bt' = ba - s 170 bt' = n - ba 172 bt' = ba - n Note: These 4 instructions set the B-Carry Digit F E R R A N T I   L T D ATLAS COMPUTER SUMMARIZED PROGRAMMING INFORMATION LONDON COMPUTER CENTRE, 68 NEWMAN ST., LONDON, W.1. Telephone: MUSeum 5040 © FERRANTI LTD 1963 Office and Works, West Gorton, Manchester 12. Telephone: East 1301 LIST CS 384 June 1963
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