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Welcome to my personal home page. There are many pages on this site concerning various topics of an entertaining, yet somewhat technical, nature that many visitors should find fascinating.

The striking image on the entry page is from the section on the Mandelbrot Function.

The following link may be used to download and install the free-to-play game Raid: Shadow Legends. Note that this game is supported by optional in-game purchases; enjoy with discretion. Its object is to collect and build up powerful heroes for your team. It is available for several different platforms: Microsoft Windows on PC-compatible computers, the Macintosh, Android, and iOS.

The link offered at the beginning of the paragraph above is essentially an affiliate link: I may recieve in-game rewards if you keep progressing, and apparently so do you recieve extra ones for joining through this type of link as well, so the benefit is mutual.

It recieved a favorable review on this page and also this page on the same site; it was, in fact, seeing the latter review that led me to try it. Another positive review also appears here on another site.

Recent Updates:

A page has been added containing a brief chronology of the typewriter, highlighting various technical innovations in its history. Illustrations of some of the kinds of typewriter discussed have now been added. Another thing added, to this page, part of a discussion of extending the capabilities of the Selectric Composer, are samples of text typed on the IBM Executive Typewriter and the IBM Selectric Composer, and even the Vari-Typer, so that the reader can get some idea of their print quality. That discussion continues to, and concludes on, this page, which goes step by step through how I start from the principle of combining the capabilities of an ordinary Selectric typewriter with those of the Selectric Composer in a single machine, and continue by adding features to overcome some of the perceived limitations of the Selectric Composer. The pitfalls one runs into when trying to make a single machine so versatile are exhibited, and in some cases discussed. There is also a new page giving a history of computers in general, and the microcomputer revolution in particular. More recently, I have added this page, which, as it discusses recent events with respect to video cards, is related to that history of computers.

Do you live in Australia? This page explains why you have a unique opportunity to prove that the Earth is not flat, after all.

My page on Floating-Point Formats now mentions the floating-point format used by the TC-16 computer in the People's Republic of China, and by the Model 709, which was the prototype for it, as well, which is the first format I have encountered that does not seem to fit in my categorization of floating-point formats as belonging to three fundamental groups.

I have now added a page about devices used for lettering to the end of my pages about keyboards, as the legends on many keyboards were originally drawn using such devices rather than being printed with printer's type.

On my page about the Korean typewriter, having finally found significant new information about the mysterious Selectric element for typing in Korean, I have added this information at the bottom of that page. Also, on my page about large keyboards, I've accompanied the existing diagram of the Space Cadet keyboard by one of the Knight keyboard and one of the SAIL keyboard which preceded it, and I have also included a diagram of the keyboard of the 9210 Scientific Descriptive Printer, which was used for preparing programs in COLASL to run on the IBM STRETCH computer (the prototype of the IBM 7030). Also added are keyboard diagrams for both the Laning and Zierler system and the Klerer-May system. As well, on my page commenting on the keyboards for the IBM PC, I've added diagrams of the keyboards for the SANYO MBC-550 computer, the Spectravideo SV-328, the Televideo TS-1603, and the Fortune Systems 32:16, as well as replacing the small diagram of the keyboard of the Radio Shack Model II computer with a larger one. Also, more accurate diagrams of the appearance of the original keyboards for the IBM Personal Computer and the IBM Personal Computer AT, as well as the IBM Enhanced Keyboard, have been added.

After a long period of inactivity, my pages on Map Projections have, as their first addition of the current new series, a page concerning the conformal projection of the world on an ellipse! And (without waiting to complete the project of updating my own BASIC program to draw this one as well) I have also added on the following page the Adams-Cahill conformal projection of the world on the surface of an octahedron by means of the Dixon elliptic functions. Since then, another five pages have been added: one on the new Equal Earth projection, one on the Boggs Eumorphic projection, one on the Strebe projection, and one on perspective projections, as well as the page noted in the paragraph below on the Dietrich-Kitada projection. Additions have also been made to several other pages, including the ones about the Mercator projection, the Bonne projection, the Mollweide projection, the Hammer-Aitoff projection, Lambert's Conformal Conic projection, and even the Winkel Tripel projection. Possibly of particular interest, my page on the Ginzburg Projection now has coverage of the closely related Latitudinally Equal Differential Polyconic Projection, widely used for world maps in the People's Republic of China.

Unfortunately, I now realize that there may have been errors in my calculation of how the Dietrich-Kitada projection worked. I have corrected one, but there is likely to be another error as well.

And now I have perhaps made the most exciting addition to the section on map projections yet. Many years ago, at the library specializing in maps at the University I attended, I noticed an old German book with a lot of maps in an unusual projection I hadn't seen before. It stuck in my mind. Eventually, I learned about the Van der Grinten IV projection, and assumed that this was the map projection I had seen so long ago. But I learned that I was mistaken. A forum post by a noted cartographer, on the web site of his company, noted that one Bruno Dietrich wrote an unusual book with many thematic maps in a novel map projection, not described, and years later, a Japanese cartographer, Kozo Kitada, assuming the projection was equal-area, as it appeared to be, worked out what the construction of the projection must have been. The forum post described enough of its properties that I was able, particularly with the aid of maps on-line in that projection to let me see what I was aiming at, to also work out how that projection would have had to work. So my site now has a page on what that map projection really was - it turns out that instead of being a conventional projection like the Van der Grinten IV, it was equal-area - and (after a difficult debugging session) I got my little BASIC map-drawing program to handle that projection (it may be the second map-drawing program in existence that does so), so now I present my web page about the Dietrich-Kitada projection.

Having on this site both a page discussing, at length, measurements used by printers and a page going into detail about unit systems used for some typesetting machines, I have finally decided that it would also be appropriate to add a page illustrating the development of typefaces over the years. This brief page goes very quickly over the highlights of the story that can be found in many introductory books about printing.

Finally, I have added to this site a page concerning one of the most popular mathematical subjects:

I had long delayed doing so, despite the topic being a natural for this page, as there are many other excellent pages on this subject on the Web. At present, it is quite a modest page on the subject, and I do expect to expand it.

Cryptography Entry Page
Index Page

Pencil and Paper SystemsElectrical and Mechanical Cipher MachinesTelecipher MachinesThe Computer EraPublic-Key CryptographyMiscellaneous Topics

Map Projections Entry/Index Page

Cylindrical ProjectionsAzimuthal ProjectionsConic ProjectionsPseudocylindrical and Pseudoconic ProjectionsPolyconic ProjectionsConventional ProjectionsOther Conformal ProjectionsOther Equal-Area ProjectionsMiscellaneous Projections

A brief page with a few annotations about the Girl Genius web comic, for which a link banner appears to the right, is now on this site.


Featured Images

A Short History of Type

A Brief Chronology of the Typewriter

Signal Flag Systems
The Vocalization of Hebrew
Introduction to HTML
Color Charts
Building Blocks and the Pythagorean Triangle
Efficient and Flexible Text Encoding
Design for a Tall Building

Movie and TV Aspect Ratios
A Limitation of Color Photography
Color Filter Array Designs

Don't Touch That Dial!
Color Television Madness
Four Speakers from Two Channels?
A Problem in Applied Geometry

Chinese Character Encodings

A Phonemic Alphabet
Two Schemes For Elections
Patterns in Nature and Myth

A Note on Large Numbers
A Unified Architecture for Telephone Numbers
On Philosophy and Ethics


A Brief History of Computers in General, and the Personal Computer in ParticularHow Does A Computer Work?What Computers Are Made FromComputer ArithmeticThe General Layout of a ComputerThe Subroutine CallThe Old Days: Computing Without RAMThe Old Days: Decimal ComputersInterleaved Memory and StridePipelined and Out-of-Order ProcessingClassic VLIWThe Perfect Computer?Minimizing ChangeNot Quite RISCA Historical View of FORTRANRemembering APLComputer Architectural PreferencesComputer Front PanelsThe Punched CardPrint Train TriviaPrinting Terminals and Proportional SpacingDigital Magnetic Tape RecordingReforming ASCII and Unicode

Keyboards Entry/Index Page

Large KeyboardsKeyboards for Genuinely Large Character SetsComments on the Keyboard of the IBM PCKeyboard ArrangementsThe Keyboard Overlay ProblemMaking Keyboards More CompactAn Attempt at a Popular KeyboardAnother Problem in Applied GeometryScan Codes Demystified


The Slide RuleInfinityArchimedean SolidsPolycube PuzzlesThe Fourth DimensionRotations of a DodecahedronExamples of GroupsTwo Famous EquationsEuler's ConstantSquaring the CircleThe Weird World of the GudermannianSphere PackingsGödel's Theorem and the Halting ProblemMagic SquaresThe Mandelbrot FunctionDiophantus at the Printer's ShopChange RingingNotations for FractionsAlternate Number BasesBayesian Statistics and the Doomsday ArgumentProbability

Tilings Entry/Index Page

The 17 Wallpaper GroupsPentagonal TilingsOctagonal TilingsDodecagonal TilingsHeptagonal Tilings

Chess Entry/Index Page

The Rules of ChessA Little History

A Few OpeningsChess NotationThe Immortal Game (Anderssen-Kieseritzky)The Immortal 50th Game (La Bourdonnais-MacDonnell)

Comments on the RulesThe Crisis in ChessDynamic ScoringA Proposed Rating SystemTournament Tiebreaking

Well-Known Forms of ChessTraditional Enlarged Forms of ChessWarring States ChessThe Game of the Three KingdomsJetan, Barsoom's Game of ChessThe Game of BattleChess-DraughtsHexagonal ChessHexagonal Chess, Part 2Triangular Chess?S. Waider's Chess for Three PlayersEnlarged and Improved ChessFour-Player ChessThe Game of War

Leaping Bat ChessRandom Variant ChessChess 2016Corrected Random Variant ChessOriginal Random Variant ChessThree-Dimensional ChessEngagement ChessFive-Player ChessAn Unusual Board for Three-Player ChessSpectral Realm ChessHalf-Shogi ChessTemporary Marsellais ChessAntimatter Universe ChessAn Ordinary VariantAntimatter Universe Flag ChessYet Another Ordinary VariantRotating Spaceship ChessA Problem CorrectedPrequel ChessReformed ShatranjTwo Off-Centre Ordinary VariantsSnake ChessTomorrow's Chess?Tiebraker ChessExciting ChessWinning Chess

Checkers Entry/Index Page

Two-Move and Three-Move RestrictionsThe Perfect Game [of checkers]?Other Forms of CheckersHasami Shogi, Seega, and Other Related GamesLudus LatrunculorumEnglish Gothic Double Checkers

Board Games

Board Games Other Than ChessA Few Board Games of InterestComments on Wei Ch'i (or Go, or Baduk)Other Uses for a Go BoardThe Greatest Modern Board Game of SkillBackgammonThe Jungle GameRithmomachyThe Perfect [board] Game?Making Wargames More ComplicatedMaking Full Use of Three Ordinary DiceThe World is RoundMaking Board Games More ComplicatedSpace Battles in Three DimensionsThe Real Game of BridgeSiberian Semi-Contract Whist (or Bridge)Bridge for Six: Trivial WhistCounting Tricks Before They're HatchedThe Semi-Tarock Deck

Science Entry/Index Page

A Few Words About StarsA Space Habitat DesignTravel to MarsLining up the PlanetsThe Equation of TimeIntroducing Special RelativityThe Inconstant MoonThe Einstein-Podolsky-Rosen experimentsThe Fine-Structure ConstantPunctuated Equilibria

Telescopes Entry/Index Page

How a Telescope WorksKinds of TelescopesTelescope MountingsEyepiecesIntroduction to Geometrical Optics

Calendars Entry/Index Page

Perpetual CalendarsA Luni-Solar CalendarA Simplified Calendar ProposalJulian Day NumbersA Martian CalendarA Modest Proposal for the Abolition of the Leap SecondHappy Easter!Happy Hanukkah!The Mayan Calendar

Unit Conversions Unit Conversions

Printer's UnitsTemperature ScalesFrom Gold Coins to Cadmium LightGauge is Not ScaleThe Size of the Piano KeyboardSome Unusual Units of LengthOld Feet and Old PoundsAvoiding the Metric System


The Musical ScaleMore Complicated TemperamentsA Bit About Musical NotationSome Interesting KeyboardsA Bit About ChordsApproximating Equal TemperamentThe Hammond OrganA Minor Mystery: The Chorus Tone GeneratorHow Does a Violin Work?

A Computer Architecture
A Computer Architecture
Entry/Index Page

Memory-Reference InstructionsAdditional InstructionsBasic ArchitectureTagged Operation ModesRestricted FunctionalityOff-Chip Processing

Concertina II
Entry/Index Page

Instruction SetOpcodes

A Computer Language
A Computer Language
Preview Page

Basic InformationWriting an EXALT ProgramArithmetic StatementsControl StructuresType DeclarationStorage ClassesSubprogramsParallel ProcessingUser-Defined TypesProgram Source ModificationExpression EvaluationInput/OutputDatabase ManagementException HandlingAdvanced FeaturesAppendix II: Implementation Notes

Contact Information and Notes

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Here is an Amazon link to an author (one David N. Brown, of Mesa, Arizona). Without an affiliate code, so I won't make money if you buy his books. This is here to help deal with malicious USENET posts about the author which currently have an unjustified high search ranking.

Here are some other legitimate links about this author.

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Copyright (c) 2000, 2001, 2002, 2004, 2005, 2008, 2010, 2011, 2012 John J. G. Savard