preface ;;Quote: programmer's manual for the Ferranti Mark I based on the Manchester "baby" machine

preface+;;Quote: understand the programmer's manual through the machine itself

1 ;;Quote: computers carry out any definite rule of thumb process that a human could do in a disciplined but unintelligent manner

1+;;Quote: computers are like a human with a desk calculator and paper obeying explicit instructions

3 ;;Quote: use the 5-bit teleprinter code to represent binary numbers; 0=/, 1=E, 2=@, 3=A; need to memorize

3+;;Quote: Turing wrote binary numbers with the low-bit first, divided into blocks of five

4 ;;Quote: the magnetic store is divided into tracks; each half-track is loaded into a page of memory; each page, a cathode ray tube, contains 64 lines of 20 binary digits each

7 ;;Quote: the state of the machine at one prepulse is completely determined by its state at the previous one; consists of electronic store, accumulator, and instruction number

7+;;Quote: programming is not interested in the state of the machine at every moment; only at prepulses

7+;;Quote: the transition function is 'obeying an instruction'

11 ;;Quote: use check sheets to verify a routine experimentally; step through the routine, recording all details

11+;;Quote: a large character indicates the same character repeated eight times

24 ;;Quote: use dummy stops to stop machine in between major operations

24 ;;Quote: use hoot instructions to listen to a routine's progress; repeated pulses generates a steady note, rich in harmonies; a single pulse is audible

25 ;;Quote: use switches for experimenter input; e.g., finding zero of a function or playing chess

25 ;;Quote: the Ferranti Mark I included a hardware random number generator; e.g., random walk probability

26 ;;Quote: the Ferranti Mark I included a real-time clock accurate to five seconds

44 ;;Quote: stepping through a program and comparing the results to a check sheet is the quickest way to find errors

44+;;Quote: the monitor tubes show the current state of the machine

48 ;;Quote: need conventions to reduce uncertainty about a machine's state; computers have very great flexibility

49 ;;Quote: always keep the powers-of-two table and the routine changing sequence (PERM) in memory; the later simplifies call and return from a routine

59 ;;Quote: programs should only depend on the official account of a subroutine, not speed; allows alteration

59 ;;Quote: programming is controlling the activity of a digital computer by expressing one's will on punched tapes and other input medium

59 ;;Quote: programming is achieved by working up from simple requirements to more complex ones; e.g., Fourier analysis via cosine calculations

59+;;Quote: the subroutines of any routine may themselves have subroutines; like bigger and lesser fleas

60 ;;Quote: a routine calculates a function of the state of the machine and stores the result, independent of the majority of the content of the store

61 ;;Quote: advice on programming, make a plan; a baffling piece of advice that is independent of rules

61 ;;Quote: programming must balance machine time, storage space, programmer's time, and result accuracy; they all cost something

63 ;;Quote: to estimate timing for a routine, the plan should include the instructions in the inner loop

63 ;;Quote: if you can think of a method using pencil and paper, you can usually implement it by machine

63 ;;Quote: break a problem into subroutines; this simplifies the problem and creates useful routines for other problems

63 ;;Quote: program subroutines before the main program; subroutine definition may change and details are not known until later

64 ;;Quote: use block schematic diagrams for subroutine planning; blocks of English joined by arrows; replace blocks by instructions

64+;;Quote: in block schematic diagrams, annotate test arrows with the tested item or loop count

65 ;;Quote: keep pages about five-sixths full with extra space after each sequence of instructions; use for fixing mistakes or storing numbers

66 ;;Quote: program repetitive instructions as First Part, Entry Point, Second Part, Loop Test; place loop count at beginning or end

75 ;;Quote: describe a routine accurately; include preconditions, postconditions, validity conditions, accuracy, time taken, and method

79 ;;Quote: intermittent machine errors are exasperating; run tests, check identities, make duplicate runs

79+;;Quote: use burst computations to workaround intermittent machine errors; if both burst runs differ, rerun using saved state

80 ;;Quote: run programmed checks often to detect problems early, avoid disastrous results, and diagnosis problems

81 ;;Quote: check sheets will catch most errors if performed conscientiously; forget purpose and method of the machine to avoid anticipating a result

81 ;;Quote: check sheets miss errors due to preconceived ideas, insufficient test cases, not checking alterations, or alternating check sheet but not the program

82 ;;Quote: check sheets should test every instruction of the program and all points of difficulty

84 ;;Quote: check magnetic tracks by computing checksums of their contents and comparing with known good values

84 ;;Quote: summary of Ferranti Mark I on a cheat sheet; functions, instruction codes, character codes, input and PERM routine, conventions