ORIGINALLY PUBLISHED IN LIMA NEWSLETTER SEPTEMBER 1994
 
      TI'S OFFICIAL EQUIVALENT OF "TEACH YOURSELF
     ASSEMBLY LANGUAGE"  
          described by Charles Good 
          Lima Ohio User Group 
      
          We had the blue book that came with the console and the "Teach
     Yourself  Basic" cassette to help us learn TI BASIC.  We had the
     "Teach Yourself Extended Basic" to help us learn XB.  And TI gave us
     the EA manual to help us learn 9900 assembly language.  The only
     problem is that the EA manual is not in any way an assembly language
     tutorial.  It is a very complicated reference guide.  For years TI
     owners have desired an assembly language course, and for years one has
     existed.  TI's official assembly language tutorial was published not
     by TI's Consumer Products Group (which produced all 99/4A hardware and
     software) but by the company's Digital Systems Group.  A copy of the
     first edition of this 1979 assembly language tutorial came to light at
     the 1992 Chicago faire and was acquired by Lee Bendick.  Now I have
     been given a complete set of the second edition. 
           
          That's right, I said 990, not 9900.  The only official TI module
     actually developed on a 99/4A system using the Editor/Assembler
     package was the game Hopper.  All other assembly language software for
     the 99/4 and 99/4A was written on computers that used TI's 990 cpu,
     mostly on the 990/10 "mini computer".  These computers had 64K of
     memory to play with, a 16 bit data bus to major peripherals, and were
     physically quite large.  They had reel to reel tape drives the size of
     a tall somewhat narrow refrigerator with a big glass door you opened
     to get at the tape.  The hard drives of 990 systems were the size of
     washing machines, and like washing machines in the spin cycle these
     hard drives took lots of time to get up to full speed when they were
     turned on.  Card readers, type writer-like printers, and 8 inch disk
     drives were parts of these computers.  The keyboard and CPU display
     included a box full of LEDs and switches.  The LEDs could show memory
     and register contents and the switches could be used to alter these
     values.  When you turned all these components on at once the room
     lights were likely to dim.  As I write this article, one of these
     computers is sitting on the loading dock of the technical school
     laboratory building where I work waiting to be junked.  This is the
     type of monsterous "mini computer" that was used for serious computing
     at the time the 99/4 "micro computer" was released in 1979.  
           
          What I have is the "990 Software Development Using the DS990
     System Self Study Guide"; original issue 1 April 1979, revision 15
     February 1982.  I have the 1982 revision.  This includes volume 1 and
     2 of the self study guide (TI part numbers 2267627-9701 and
     2267627-9702), a nice binder (TI part 2309913-0001) containing a set
     of 8 audio C60 cassette tapes recorded on both sides (TI part numbers
     2309914-0001 through -0008, copyright 1979) that are keyed to specific
     pages in the self study guide, and the "DX10 Operators Self study
     Guide" (TI part 2267629-9701, copyright 1981) which describes the
     operation system (the DOS) used on the DS990 computer.  All of these
     are published by TI's "Education and Development Center, Digital
     Systems Group". 
           
          9900 assembly language is a very large subset of 990 assembly
     language, containing 69 of the 990's 72 kinds of instructions.  This
     means that almost everything learned about 990 assembly language in
     this official TI tutorial would be helpful in mastering assembly
     programming on a 99/4A system.  This tutorial, with its accompanying
     audio tapes was probably used by TI to help train the programmers who
     wrote assembly code contained in 99/4A command modules.  This is
     suggested by side 1 of tape 2 and pages 4-3 of the study guide which
     state, "This module covers the assembly language instruction set for
     the 990 computer family and the TMS 9900 microprocessor.  This
     instruction set is upwardly compatible; in other words, programs you
     write for the TMS 9900 microprocessor can also run on the other
     members of the 990 computer family." 
           
          Each lesson is on an audio cassette tape.  You are supposed to
     have the the study guide in front of you as you listen to the tape.
     Each lesson is divided into very short segments.  You can stop the
     tape and replay these segments until they are understood.  Some
     lessons are specific to the 990/10 computer hardware and DX10
     operating system  and describe use of the particular editor and
     assembler used on this computer.  But at least half of the lesson
     pages and audio tapes are appropriate those interested in learning
     assembly programming on and for the 99/4A.  In particular, the lession
     called "Instruction Set" (lesson 4) would be useful.  This includes
     both sides of 3 of the 8 audio tapes and 174 pages of text.   What you
     don't get in these lessons is specific information on programming the
     "bells and whistles" of a 99/4A such as color graphics, sprites,
     and music. 
      
          This rare documentaiton is available by copy or loan to members
     of the Lima User Group.  We charge 3 cents per page for copying pages.
     Audio tape copying, on your blank tapes, is free. 
     .PL 1