Howdy,

Here are a bunch of programs that you may find interesting.
Besides the ones listed in a FILES /1, there are also several
BASIC programs.

PATCH1.5 is a program to allow the reatributing of attribute
      protected files on PTDOS1.5 (not 1.4). I don't have
      the source code unfortunately but it is pretty simple.
      Type PATCH1.5 and it will execute and return to
      PTDOS. Then REATR the file(s). For safety, you should
      re-boot afterwards as PTDOS will continue to ignore
      the attribute protects.

MESSAGE, !MESSAGE, BUILD, MES.S, and MES.TEMP are a group of
      useless programs I did for fun. Studying the source
      is a good way (maybe) to understand how to use the
      overlay handler and how to interface to PTDOS in general.

      MESSAGE will type a random (almost) message on the screen
      whenever run. I use it in my START.UP file to avoid
      the same old boot-ups over and over.

      !MESSAGE is a utility file that contains the 32 messages
      that MESSAGE may choose from. !MESSAGE should be on
      the default diskette.

      MES.S is the source code for MESSAGE.

      BUILD is a DO file that I use to create or replace
      messages in the utility file !MESSAGE. It expects to run
      on the default disk and requires !MESSAGE and MES.TEMP.

      MES.TEMP is the source file for a message.

FORMAT is the text formatter originally described in Software
      Tools, by Kernighan and Plauger. This version was
      written by Mike Gabrielson and printed in the May 79
      issue of Dr. Dobb's. I added the necessary interfacing
      to work with PTDOS. Mostly what I'm donating here, is
      the typing effort. I don't think it violates anything
      and Gabrielson includes no copyright message so I
      assume it is for general use. I did not include the
      comments when I entered the code so one should
      reference Dr. Dobbs and Software Tools for help
      with the program. Type FORMAT sourcefile, outfile.
      Enter #1 in outfile to run to screen. FORMAT.S
      is the source file. TEXT is a sample file to be
      formatted.

Extended Disk BASIC programs:
 (actually, these should all run on extended cassette BASIC too)

PRIMES is a fast program for generating prime numbers. The
      algorithm is from a fairly recent CACM article by
      Gries. I'm sorry I don't have the date. The program
      could be extended by using PEEKs and POKEs instead
      of an array to represent the sieve as each element
      in the sieve can have only two values.

FACTOR is a program to factor an integer into it's prime
      components. It utilizes the same algorithm as the
      PRIMES program and could be extended in the same way.

KWIKSORT is a quiksort or partition-exchange sort. Is neat
      in that it utilizes user-definable multi-line functions
      recursively, with aoutomatic stacking of local variables.

QUIKSORT same as above but with modifications suggested by
      Knuth.

HEAPSORT from Knuth

SHELSORT from Knuth

SORT is another sort suggested by Knuth which seems to
      approach the speed of the quiksort but may not have
      the disadvantages(when the file is in order, for example)
      Knuth rates the mathematical evaluation of this
      sort at 50 points, his maximum.

MAZE is another example using recursive functions. It was
      inspired by a contest a friend entered in which the
      object was to find the longest possible word in a
      given matrix of random letters. The words are allowed
      to twist and turn as much as necessary but must not
      use the same letter twice. Try words like: location,
      tatterdemalion, pharmaceutical to see it work.
      (Should be entered in lower-case)

FIND+ was originally inspired by the IEEE mico-mouse contest.
      This was the best program I came up with, and it
      naturally uses a recursive function. Note that it
      will require lots of memory to run! SET your BUffer
      = 9000h and use the MBASIC on this disk.

FIND another mouse program but with a unique idea that
      causes interesting behaviour sometimes.
      Consider an array where the walls are valued at 999
      and the corriders are set at 0 and the "cookie" is
      set at -1. Have the mouse increment any location
      he's at by 1 and then go to the lowest adjacent
      number. It works but looks funny sometimes. Also
      takes much less memory than FIND+. Watch its
      behaviour in the top right corner.

PERMTEST generates the all the permutations of a given
      array in order. Makes a good problem. This
      algorithm from Dijkstra.

I also have the commented, source code for the Falconer
Floating Point package (Dr. Dobb's, March and April 79) on
disk. If you want it, I'll send it along, but read his
copyright notices etc... in the March issue first to be
sure it's legal. It took about 3 days to type but is a very
nice package. Based on 3 bytes however, so it would not
be the best package for use with the Pascal.

Have you seen any update documentation for PTDOS 1.5 (rev G)?
We have the disk here, but the only change I have found is an
improved DBASIC which cuts out the need for ZIP 0 etc ...
Have you been able to make XREF work as described in the
manual? For me, it lists the lines numbers for each symbol, but
no cross-ref line numbers, and the value shown for the symbol
is incorrect (typically the first address of the program).
I heard once that a EDBASIC was to be released that ran in the
top 12K of a 64K system and wrapped around to allow bigger
programs. Has anyone got it?

I'm looking forward to getting the SLAC Pascal. It sounds like a
good system. I especially like being able to get the source
code for everything. Should interface an AM9511 chip to the SOL
and rewrite the P-Code interpreter to take advantage of it's
floating point and integer arithmetic capabilities.

You have a good newsletter and I look forward to the next issue.

Thank you,

Preston Briggs

Interactive Computers, Clear Lake City