What this comparison shows

Two guidance computers, one clock

Both machines flew on the same vehicle, and both were clocked at 2.048 MHz. The multiplier on the clock row is therefore exactly 1×, and it says nothing at all about which computer did more work per second.

The instruction timings say it instead. They are the figures to read here, because on a core-memory machine an instruction time is a whole number of memory cycles, and the cycle is a physical property of the machine rather than a benchmark result. Each instruction is its own comparability group: an addition time and a multiplication time were obtained by timing different work. The multipliers therefore compare addition with addition and multiplication with multiplication.

Both machines have a rated power consumption from their own documentation, and the two figures are not turned into a multiplier, because a design rating states what a machine was specified to draw and not what it drew under any reproducible workload. Two ratings from two programs, fifteen years apart in engineering practice, would produce a number with no defensible meaning.

At a glance

This card lists what each record states. These are the six questions every machine in the catalog is asked. A row with answers from different methods has no bar or multiplier; the line beneath it explains the difference.

Question	Apollo Guidance Computer (Block II)MIT Instrumentation Laboratory / RaytheonGuidance computer · 1966Block II flight configuration	Saturn Launch Vehicle Digital ComputerIBM Federal Systems DivisionGuidance computer · 1966Four memory modules
CPU clock	Apollo Guidance Computer (Block II) (Block II flight configuration)2.048 MHzApollo Guidance Computer Block II processorConfirmed	Saturn Launch Vehicle Digital Computer (Four memory modules)2.048 MHzSaturn Launch Vehicle Digital ComputerConfirmed
Methods, caveats and sources for cpu clock Where these sit among 65 machines recorded this way 2 MHzBBC Micro Model B 2.048 MHzApollo Guidance Computer (Block II) 2.048 MHzSaturn Launch Vehicle Digital Computer 2.68 MHzSuper Nintendo Entertainment System Apollo Guidance Computer (Block II) — 8th-lowest of the 65 figures recorded this way. Saturn Launch Vehicle Digital Computer — 8th-lowest of the 65 figures recorded this way. Positions on a linear scale. See all 65 over time.
GPU clock	Apollo Guidance Computer (Block II) (Block II flight configuration)not applicableno gpu component is fitted to this record	Saturn Launch Vehicle Digital Computer (Four memory modules)not applicableno gpu component is fitted to this record
Memory capacity	Apollo Guidance Computer (Block II) (Block II flight configuration)2048 wordsConfirmed	Saturn Launch Vehicle Digital Computer (Four memory modules)not recorded for this variant
Memory bandwidth	Apollo Guidance Computer (Block II) (Block II flight configuration)unknownThe report describes the memory by cycle time and word length rather than by a transfer rate, which is how core-memory machines were specified.	Saturn Launch Vehicle Digital Computer (Four memory modules)unknownThe report specifies the memory by module capacity, word length and cycle time, and states no transfer rate.
Peak FP32	Apollo Guidance Computer (Block II) (Block II flight configuration)not applicableApollo Guidance Computer Block II processorThe AGC has no floating-point hardware. Its arithmetic unit is a one's-complement fixed-point adder with shifting gates, so there is no rate to state — the question does not apply.	Saturn Launch Vehicle Digital Computer (Four memory modules)not applicableSaturn Launch Vehicle Digital ComputerThe LVDC is a fixed-point machine, as its own characteristics table states in the type row. There is no floating-point rate to give.
Power	Apollo Guidance Computer (Block II) (Block II flight configuration)70 WConfirmed	Saturn Launch Vehicle Digital Computer (Four memory modules)137.0 WConfirmed
Methods, caveats and sources for power

Apollo Guidance Computer (Block II) (Block II flight configuration), the first record, is the multiplier baseline. Each section covers its own metrics. This comparison has no overall score. Bars are drawn to scale within a row and carry no number of their own.

Processing

Instruction rates, floating-point peaks, benchmark results and clocks. None of these converts into another.

Clock frequencycpu

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Nominal clock	Apollo Guidance Computer (Block II) (Block II flight configuration)2.048 MHzConfirmed baseline Recorded as Apollo Guidance Computer Block II processor: Vendor-rated. Stated by the vendor. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)2.048 MHzConfirmed 1×the baselinecaveat Recorded as Saturn Launch Vehicle Digital Computer: Vendor-rated. Stated by the vendor. Caveat The same clock rate as the Apollo Guidance Computer, and the coincidence says nothing about their speed: the LVDC is a serial machine that spends four clocks per bit, so it adds in 82 µs against the AGC's 23.4 µs. Multiplier `a ÷ b` (ratio v1, to 4 significant digits) Saturn Launch Vehicle Digital Computer: 2.048 MHz Apollo Guidance Computer (Block II): 2.048 MHz Compares clock-frequency at cpu scope, obtained by nominal-clock. Valid only within this comparability group, and reported to 4 significant digits — the precision of the least precise input. Sources ntrs-19700023342

Peak FP32 ratecpu

Both records address this quantity, but neither states a value. The figures are recorded as an explicit absence, so there is nothing to compare.

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Theoretical peak	Apollo Guidance Computer (Block II) (Block II flight configuration)not applicableThe AGC has no floating-point hardware. Its arithmetic unit is a one's-complement fixed-point adder with shifting gates, so there is no rate to state — the question does not apply. baseline Recorded as Apollo Guidance Computer Block II processor: Stated by the vendor. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)not applicableThe LVDC is a fixed-point machine, as its own characteristics table states in the type row. There is no floating-point rate to give. baseline states none Recorded as Saturn Launch Vehicle Digital Computer: Stated by the vendor. Multiplier No multiplier: Apollo Guidance Computer (Block II) (Block II flight configuration) records no value here, so there is nothing to divide by. Sources ntrs-19700023342

Peak FP64 ratecpu

Both records address this quantity, but neither states a value. The figures are recorded as an explicit absence, so there is nothing to compare.

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Theoretical peak	Apollo Guidance Computer (Block II) (Block II flight configuration)not applicableNo floating-point hardware. The double-precision instructions in the Block II order code operate on pairs of 15 bit fixed-point words, which is not double-precision floating point. baseline Recorded as Apollo Guidance Computer Block II processor: Stated by the vendor. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)not applicableFixed-point machine. The 26 bit data word carries 25 magnitude bits and a sign bit, not an exponent. baseline states none Recorded as Saturn Launch Vehicle Digital Computer: Stated by the vendor. Multiplier No multiplier: Apollo Guidance Computer (Block II) (Block II flight configuration) records no value here, so there is nothing to divide by. Sources ntrs-19700023342

Instruction execution timecpu

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Addition instruction	Apollo Guidance Computer (Block II) (Block II flight configuration)23.4 µsConfirmed baseline Recorded as Apollo Guidance Computer Block II processor: Vendor-rated. Stated by the vendor. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)82 µsConfirmed 3.5×the baseline Recorded as Saturn Launch Vehicle Digital Computer: Vendor-rated. Stated by the vendor. Multiplier `a ÷ b` (ratio v1, to 2 significant digits) Saturn Launch Vehicle Digital Computer: 82 µs Apollo Guidance Computer (Block II): 23.4 µs Compares instruction-execution-time at cpu scope, obtained by add-instruction. Valid only within this comparability group, and reported to 2 significant digits — the precision of the least precise input. Sources ntrs-19700023342
Division instruction	Apollo Guidance Computer (Block II) (Block II flight configuration)not recorded	Saturn Launch Vehicle Digital Computer (Four memory modules)656 µsConfirmed baseline states none Recorded as Saturn Launch Vehicle Digital Computer: Vendor-rated. Stated by the vendor. Multiplier No multiplier: Apollo Guidance Computer (Block II) (Block II flight configuration) records no value here, so there is nothing to divide by. Sources ntrs-19700023342
Multiplication instruction	Apollo Guidance Computer (Block II) (Block II flight configuration)46.8 µsConfirmed baselinecaveat Recorded as Apollo Guidance Computer Block II processor: Vendor-rated. Stated by the vendor. Caveat Not comparable with the addition time: a different instruction is a different comparability group, and the ratio between them describes this machine's order code rather than its speed. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)328 µsConfirmed 7.01×the baseline Recorded as Saturn Launch Vehicle Digital Computer: Vendor-rated. Stated by the vendor. Multiplier `a ÷ b` (ratio v1, to 3 significant digits) Saturn Launch Vehicle Digital Computer: 328 µs Apollo Guidance Computer (Block II): 46.8 µs Compares instruction-execution-time at cpu scope, obtained by multiply-instruction. Valid only within this comparability group, and reported to 3 significant digits — the precision of the least precise input. Sources ntrs-19700023342

Memory

Capacity, bandwidth, bus width and timing. Binary and decimal prefixes are kept as the source wrote them.

Memory capacity (words)memory

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Design capacity	Apollo Guidance Computer (Block II) (Block II flight configuration)36 864 wordsConfirmed2048 wordsConfirmed baselinecaveat Recorded as Apollo Guidance Computer core rope memory: Vendor-rated. Stated by the vendor. Apollo Guidance Computer erasable core memory: Vendor-rated. Stated by the vendor. Caveat A word is 15 bit plus parity. Converting this capacity to bytes needs the word width and is published as a derived claim, never as a unit conversion.The first eight locations are central and special registers rather than general storage. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)4096 wordsConfirmed several parts statedcaveat Recorded as Saturn LVDC toroidal core memory module: Vendor-rated. Stated by the vendor. Caveat A word here is 28 bit, against the Apollo Guidance Computer's 16. Word counts from machines with different word widths are not a like-for-like capacity comparison. Multiplier No multiplier: the machine states this quantity for more than one part, so there is no single figure to divide. Sources ntrs-19700023342

Memory capacity (words)whole-system

Only one of these records states this figure in this form, so there is nothing here to compare it with.

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Design capacity	Apollo Guidance Computer (Block II) (Block II flight configuration)2048 wordsConfirmed baselinecaveat Recorded as Derived. Computed here from figures the vendor stated. Caveat Adds 1 memory-capacity-words figure obtained by design-capacity. Left out: 36 864 words of fixed rope memory (woven at manufacture and unwritable in flight, so it is storage the machine reads from rather than memory it works in). A total is only as trustworthy as the decision about what belongs in it, so both the terms and the exclusions are named records. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)not recorded

Memory bandwidthmemory

Both records address this quantity, but neither states a value. The figures are recorded as an explicit absence, so there is nothing to compare.

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Theoretical peak	Apollo Guidance Computer (Block II) (Block II flight configuration)unknownThe report describes the memory by cycle time and word length rather than by a transfer rate, which is how core-memory machines were specified. baselinecaveat Recorded as Stated by the vendor. Caveat Unknown, and the absence says something about the era rather than about the document. A machine whose timing is quoted as an 11.7 microsecond memory cycle is being described in the unit that mattered; bytes per second is a later question, and multiplying the cycle time by the word length to answer it would be this project’s arithmetic rather than the report’s. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)unknownThe report specifies the memory by module capacity, word length and cycle time, and states no transfer rate. baseline states nonecaveat Recorded as Stated by the vendor. Caveat Unknown for the same reason as the Apollo Guidance Computer’s, and the pair is worth seeing together: two machines of the same program and the same year, both described in microseconds and words, neither in bytes per second. Multiplier No multiplier: Apollo Guidance Computer (Block II) (Block II flight configuration) records no value here, so there is nothing to divide by. Sources ntrs-19700023342

Energy

A cooling-design target, a specified rating and a measured wall draw are separate quantities, and only the last supports a multiplier.

Rated power consumptionwhole-system

Method	Apollo Guidance Computer (Block II)Block II flight configuration	Saturn Launch Vehicle Digital ComputerFour memory modules
Rated power	Apollo Guidance Computer (Block II) (Block II flight configuration)70 WConfirmed baselinecaveat Recorded as Vendor-rated. Stated by the vendor. Caveat A design figure for the whole unit, not a measured draw under a stated workload and not a cooling-design target. It is not comparable with a component TDP in either direction. Sources ntrs-19760016247	Saturn Launch Vehicle Digital Computer (Four memory modules)137.0 WConfirmed not a ratiocaveat Recorded as Vendor-rated. Stated by the vendor. Caveat A design figure for the computer alone, excluding the data adapter that connects it to the rest of the instrument unit. It is not a measured draw and not a cooling-design target. Multiplier No multiplier: this quantity is not defined consistently enough for one figure to be divided by another. Sources ntrs-19700023342

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