APL Campfire

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Humorous promotional logo.

The APL Campfire was a recurring meeting hosted by Adám Brudzewsky every fourth Sunday at 18:00 UTC, from 9 May 2021 until 12 June 2022, switching to an irregular schedule after that. Each session is about an hour. The event focuses on the history of APL programming, inviting participants to tell stories of their experiences in an informal setting. The meetings are recorded for future reference.[1]

APL Campfires are held using Zoom:


The series started after Joel Wittenberg contacted Dyalog Ltd., wanting to reconnect with the APL community. He started the APL Dinosaurs Facebook group, and suggested a live meeting. Via Zoom, he met with his friend Harry Saal and Dyalog employee Adám Brudzewsky for an hour on May 9, 2021. The meeting was deemed so enjoyable, that the group decided to make it a scheduled recurring event.


Date Speakers Subjects discussed Recording
May 9 Harry J. Saal, Joel Wittenberg, Adám Brudzewsky APL on mainframes, ⎕FMT's G,[2] and more
Jun 6 Joel Wittenberg, Ron Murray Murray's history with APL, including APL/700 and the APL Machine, and at Microsoft. Wittenberg's early exposure to Iverson Notation and PAT. 1:06:28
Jul 4 Len Shustek, Joey Tuttle, Joel Wittenberg Shustek at IBM, Standord, SLAC, making APL\360 a multi-user system, running it under other OSs, MFT & (Experimental) MVT, the Computer History Museum, APL.SV, Phil S. Abrams 1:06:24
Aug 1 Gitte Christensen[3], Joey Tuttle, Joel Wittenberg Working at IPSA, Ian Sharp, 666 BOX (early email), MagicStore, meeting people online (including Morten Kromberg), Christensen's first APL application, APL conferences, the boxed/nested split, Ken Iverson's Rationalized APL and J, the Rank operator, IBM/Insight Systems/Adaytum/Cognos/Dyadic Systems/Dyalog Ltd., Alex Morrow 1:06:22
Aug 29 Ray Polivka[4], Jon McGrew, Joey Tuttle, Walter Fil, Joel Wittenberg ILLIAC, at IBM, Fred Brooks, Adin Falkoff, APL\360, IBM 7030 Stretch, IVSYS/7090, Ken Iverson, Science Research Associates, computer assisted instruction, IBM 1500, teaching APL, books (own and others'), SIGAPL, SHARE, APL conferences, Iverson Award, Garth Foster, APL Quote Quad, Minnowbrook, upcoming fourth book, APL 5100, )MSG, MCM/70 1:47:56
Sep 26 Andy Shiers[5] and Geoff Streeter 40 years of Dyalog APL, early days of Dyadic Systems 1:05:42
Oct 24 Jim Brown, Ron Murray Early days at IBM and Syracuse University. Discussions with Ken Iverson and Adin Falkoff, extending base value () and represent () to work on higher rank arrays. Ragged arrays vs nested arrays. ⎕AX as prototyping too; to switch axiom system for enclosing a scalar. Origin of foo as a placeholder name in programming. Resistance to APL at IBM. Interesting internal applications at IBM: a stock application (still in use today) and QMF (Query Management Facility). Using APL for models of primitives and extensions. Behaviour of outer product (∘.), strand notation, prototypes for each on empty arrays, system labels. NARS2000's ball arithmetic. Differences in floating point results of APL vs PL/I implementations of IBM's internal planning system. The meaning of monadic Up Arrow () and Right Shoe (). Influence from Lisp (first as and "last" as ), symbols, Mike Jenkins's Matrix Inverse and Matrix Divide (), Disjoined arrays using a dedicated Disjoined Array Computer (DAC), hardware APL machines/processors, shared variables. 1:26:13
Nov 21 Zbigniew "Ziggy" Stachniak[6], Bob Armstrong Timeline leading to MCM/70: Mers Kutt, York APL, Intel 8008, APL '73, speed of 0.7÷⍳255, battery-operation, European tour and selling the computer as a personal calculator, users of MCM/70, IBM possible "inspiration" to create the IBM 5100, the display technology, the applications libraries including games, York University Computer Museum, using APL for arts, the MCM/70 emulator. 1:09:21
Dec 19 Charles Brenner Larry Breed, Roger Moore, IBM at Yorktown Heights, Ken Iverson's A Programming Language, Adin Falkoff, Eugene McDonnell, APL\360, implementing (high-rank) Transpose and Rotate with APL models, Imlac, APL\1130, the modem precursor, generating poetry by sampling trigrams, STSC, Roy Sykes, optimised transpose of Boolean arrays, Bob Bernecky, John Gilmore, control structures, APL2000, John Scholes, Roger Hui, IPSA, dfns.dws, IBM 650, uses of APL, forensic mathematics, Adrian Smith 1:13:16


Jan 16 Curtis Jones, André Orlans, Harry Saal, Adám Brudzewsky Early days of APL. Does APL (still) have a niche? 1:07:40
Feb 13 Curtis Jones, Jon McGrew Drawing graphs of magnetic bubble memory using the 20 PLOT and 10 FINEPLOT workspace, getting the APL2 idiom list released to to SIGAPL, making TryAPL2 free for schools, computing the decay time of voic coil motors, communicating with the HP-IB, liaising between IBM departments that produced APL code, Ray Polivka's roles, editing APL Quote Quad, golfing the implementation of Conway's Game of Life, David Liebtag marking session text for execution, GRAPHPAK, STARMAP. 1:20:21
Mar 13 David Selby[7], Jon McGrew IBM Havant, speeding up Grade using radix sort, APLSV, self-learning APL, "hacking" APLSV, implementing auxiliary processors in assembly language, including AP124 for screen control, Norman D. Thomson, APL83, implementing APL for IBM System/7 and IBM Series/1 in APL/IL (Intermediate Language; an APL-like low-level macro language), Adin Falkoff, working on large data, compiling IL to RISC, the IBM APL Community, extensive internal uses of APL at IBM, APL conference disks inspired by Mike Cowlishaw, improving APL/PC, Japanese APL, hardware, IBM bureaucracy, porting APL2 to the PC, Jim Brown, the APL2 logo, porting APL2 to IBM RT PC, migrating (partially) from IL to C, comparison with other programming languages, regrets, notable personalities, Diamond 2:07:47
Apr 10 Adám Brudzewsky Growing up with APL as a "natural language", using list arithmetic to implement Boolean array logic. 01:10:44
May 8[8] Paul Jackson[9] PL/I, IBM 2741, testing arguments in lack of error trapping, "broken keyboard" exercises (implementing primitives in terms of others), ngn/apl and his extensions to it, Ken Iverson, writing various programs, comparison of typewriter terminals like IBM 3270, "STAPLE" (Strutured APL Extensions) compiling control structures to branching, auxiliary processors, MVS, SAX, Dfn, evolution of J, Variant, Index origin, modern times. 02:39:02
Jun 12[10] Paul Jackson Floating point computations, typing APL glyphs, fonts, SAX, J, running APL and J online. 01:43:11


Mar 12 Norman Thomson[11] IBM in Hursley, use of computers, PL/I, language of reasoning, teaching APL, catergories of APL users, the importance of grasping the concept of rank, APL2, anecdotes from APL conferences, Eigen analysis, J demonstration of computing and using Eigen values 1:21:52


  1. YouTube playlist
  2. "Joel Wittenberg made critical assessments of that design and suggested important elaborations which were incorporated in later designs." Adin Falkoff: A pictorial format function for patterning decorated numeric displays. APL81.
  3. 2016 Iverson Award winner.
  4. 1990 Iverson Award winner and co-author of three authoritative APL textbooks.
  5. At Dyadic Systems since 1987, now Dyalog's Chief of Operations.
  6. Computing historian, associate professor of computer science at York University in Toronto, and author of Inventing the PC.
  7. One of the highest level Data Scientists in IBM; Principal Data Scientist and Master Inventor for IBM Weather Business Solutions, AI Applications Cloud and Cognitive Software. Developed APL/PC and APL2/PC.
  8. Arranged in cooperation with with APL BUG.
  9. Was mentioned multiple times by David Selby
  10. Note: One week later than usual.
  11. Author of APL Programs for the Mathematics Classroom and co-author, with R. Polivka of APL2 in Depth.

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