Model 100 Tokenizer

A tokenizer for TRS-80 Model 100 (AKA "M100") BASIC language. Converts .DO files to .BA.

tokenize FOO.DO FOO.BA

Although, this documentation refers to the "Model 100", this program also works for the Tandy 102, Tandy 200, Kyocera Kyotronic-85, and Olivetti M10, which all have identical tokenization.

This does not work for the NEC PC-8201/8201A/8300 whose N82 BASIC has a different tokenization.

Introduction

The Tandy/Radio-Shack Model 100 portable computer can save its BASIC files in ASCII (plain text) or in a "tokenized" format where the keywords — such as FOR, IF, PRINT, REM — are converted to a single byte. Not only is this more compact, but it loads much faster.

The problem

Programs for the Model 100 are generally distributed in ASCII format, but that has two downsides: ① the user must LOAD and re-SAVE the file on their machine to tokenize it as only tokenized BASIC can be run and ② the machine may not have enough storage space for the tokenized version while the ASCII version is also in memory.

The solution

This program solves that problem by tokenizing on the host computer before downloading to the Model 100. Additionally, this project provides a decommenter and cruncher (whitespace remover) to save bytes in the tokenized output at the expense of readability.

File extension terminology

Tokenized BASIC files use the extension .BA. ASCII formatted BASIC files should be given the extension .DO so that the Model 100 will see them as text documents, although people often misuse .BA for ASCII.

Programs in this project

• tokenize: A shell script which ties together all the following.

• m100-tokenize: Convert M100 BASIC program from ASCII (.DO) to executable .BA file.

• m100-sanity: Clean up the BASIC source code (sort lines and remove duplicates).

• m100-jumps: Analyze the BASIC source code and output a list of lines that begin with a comment and that are referred to by other lines in the program. Input should have been run through m100-sanity.

• m100-decomment: Modify the BASIC source code to remove REM and ' comments except it keeps lines mentioned on the command line (output from m100-jumps). This can save a lot of space if the program was well commented.

• m100-crunch: Modify the BASIC source code to remove all whitespace in an attempt to save even more space at the expense of readability.

Compilation & Installation

Presuming you have flex installed, just run make to compile.

$ git clone https://github.com/hackerb9/tokenize
$ make
$ make install

Optionally, you can compile by hand

 flex m100-tokenize.lex  &&  gcc lex.tokenize.c

Flex creates the file lex.tokenize.c from m100-tokenize.lex. The main() routine is defined in m100-tokenize-main.c, which is #included by m100-tokenize.lex.

Usage

One can either use the tokenize wrapper or run the executables manually.

The tokenize wrapper

The "tokenize" script is easiest. By default, the output will be exactly the same, byte for byte, as a .BA file created on actual hardware.

Synopsis

tokenize INPUT.DO [ OUTPUT.BA ]
tokenize [ -d | --decomment ] INPUT.DO [ OUTPUT.BA ]
tokenize [ -c | --crunch ] INPUT.DO [ OUTPUT.BA ]

The -d option decomments before tokenizing.

The -c option decomments and removes all optional whitespace before tokenizing.

Example

$ tokenize PROG.DO
Output file 'PROG.BA' already exists. Overwrite [yes/No/rename]? R
Old file renamed to 'PROG.BA~'

Running m100-tokenize and friends manually

Certain programs should usually be run to process the input before the final tokenization step, depending upon what is wanted. m100-sanity is strongly recommended. (See Abnormal code below.)

flowchart LR;
m100-sanity ==> m100-tokenize
m100-sanity ==> m100-jumps ==> m100-decomment
m100-decomment --> m100-crunch --> m100-tokenize
m100-decomment --> m100-tokenize

Loading

Programs used	Effect	Same as
m100-sanity m100-tokenize	Identical output as a genuine Model 100	tokenize
m100-sanity m100-jumps m100-decomment m100-tokenize	Saves RAM by removing unnecessary comments	tokenize -d
m100-sanity m100-jumps m100-decomment m100-crunch m100-tokenize	Saves even more RAM, removing whitespace	tokenize -c
m100-tokenize	Abnormal code is kept as is

Click to see more details about running these programs manually

m100-tokenize synopsis

m100-tokenize [ INPUT.DO [ OUTPUT.BA ] ]

Unlike tokenize, m100-tokenize never guesses the output filename. With no files specified, the default is to use stdin and stdout so it can be used as a filter in a pipeline. The other programs -- m100-sanity, m100-jumps, m100-decomment, and m100-crunch -- all have the same syntax taking two optional filenames.

Example usage of m100-tokenize

When running m100-tokenize by hand, process the input through the m100-sanity script first to correct possibly ill-formed BASIC source code.

m100-sanity INPUT.DO | m100-tokenize > OUTPUT.BA

The above example is equivalent to running tokenize INPUT.DO OUTPUT.BA.

Example usage with decommenting

The m100-decomment program needs help from the m100-jumps program to know when it shouldn't completely remove a commented out line, for example,

10 REM This line would normally be removed
20 GOTO 10   ' ... but now line 10 should be kept.

So, first, we get the list of line numbers that must be kept in the variable $jumps and then we call m100-decomment passing in that list on the command line.

jumps=$(m100-sanity INPUT.DO | m100-jumps)
m100-sanity INPUT.DO | 
    m100-decomment - - $jumps | 
	m100-tokenize > OUTPUT.BA

The above example is equivalent to running tokenize -d INPUT.DO OUTPUT.BA.

Note that m100-decomment keeps the entire text of comments which are listed by m100-jumps with the presumption that, as targets of GOTO or GOSUB, they are the most valuable remarks in the program. (This behaviour may change in the future.)

Example output after decommenting but before tokenizing:

10 REM This line would normally be removed
20 GOTO 10

Example usage with crunching

The m100-crunch program removes all optional space and some other optional characters, such as a double-quote at the end of a line or a colon before an apostrophe. It also completely removes the text of comments which may have been preserved by m100-decomment from the m100-jumps list. In short, it makes the program extremely hard to read, but does save a few more bytes in RAM.

jumps=$(m100-sanity INPUT.DO | m100-jumps)
m100-sanity INPUT.DO | 
    m100-decomment - - $jumps | 
	m100-crunch | 
	m100-tokenize > OUTPUT.BA

The above example is equivalent to running tokenize -c INPUT.DO OUTPUT.BA.

Example output after crunching but before tokenizing:

10REM
20GOTO10

An obscure note about stdout stream rewinding

After finishing tokenizing, m100-tokenize rewinds the output file in order to correct the PL PH line pointers. Rewinding fails if the standard output is piped to another program. For example:

1. m100-tokenize FOO.DO FOO.BA
2. m100-tokenize <FOO.DO >FOO.BA
3. m100-tokenize FOO.DO | cat > FOO.BA

Note that (1) and (2) are identical, but (3) is slightly different.

In example 3, the output stream cannot be rewound and the line pointers will all contain "**" (0x2A2A). This does not matter for a genuine Model T computer which ignores PL PH in a file, but some emulators are known to be persnickety and balk.

If you find this to be a problem, please file an issue as it is potentially correctable using open_memstream(), but hackerb9 does not see the need.

Machine compatibility

Across the eight Kyotronic-85 Sisters, there are actually only two different tokenized formats. The first, which I call "M100 BASIC" is supported by this program. The second, which is known as "N82 BASIC", is not yet supported.

The TRS-80 Models 100 and 102 and the Tandy 200 all share the same tokenized BASIC. While less commonly seen, the Kyocera Kyotronic-85 and Olivetti M10 also use that tokenization, so one .BA program can work for any of them. However, the NEC family of portables -- the PC-8201, PC-8201A, and PC-8300 -- run N82 BASIC which has a different tokenization format.

Why Lex?

This program is written in Flex, a lexical analyzer, because it made implementation trivial. The tokenizer itself, m100-tokenize, is mostly just a table of keywords and the corresponding byte they should emit. Flex handles special cases, like quoted strings and REMarks, easily.

The downside is that one must have flex installed to modify the tokenizer. Flex is not necessary to compile on a machine as flex can generate portable C code. See the tokenize-cfiles.tar.gz in the github release or run make cfiles.

Abnormal code

The tokenize script always uses the m100-sanity program to clean up the source code, but one can run m100-tokenize directly to purposefully create abnormal, but valid, .BA files. These programs cannot be created on genuine hardware, but will run.

Here is an extreme example.

Source code for "GOTO 10" by hackerb9

1 I=-1
10 I=I+1: IF I MOD 1000 THEN 10 ELSE I=0
10 PRINT: PRINT
10 PRINT "This is line ten."
10 PRINT "This is also line ten."
5  PRINT "Line five runs after line ten."
10 PRINT "Where would GOTO 10 go?"
15 PRINT "  (The following line is 7 GOTO 10)"
7 GOTO 10
8 ERROR "Line 8 is skipped by GOTO 10."
10 PRINT: PRINT "It goes to the *next* line ten!"
10 FOR T=0 TO 1000: NEXT T
10 PRINT "Exceptions: Goes to *first* line ten"
10 PRINT "  if the current line is ten, or"
10 PRINT "  if a line number > 10 is seen."
10
10 'Shouldn't 10 GOTO 10 go to itself?
10 'It shouldn't have to search at all.
10 'Maybe it's a bug in Tandy BASIC?
10 'Perhaps it checks for (line >= 10)
10 'before it checks for (line == 10)?
10
10 'BTW, >= is one less op than >.
10 'On 8085, >= is CMP then check CY==0.
10 'But > also requires checking Z==0.
10
10 PRINT
10 PRINT "The next line is 9 GOTO 10. This time"
10 PRINT "it goes to the FIRST line ten, because"
10 PRINT "line 20 comes before the next line ten."
9 GOTO 10
20 ERROR "Line 20 is never reached, but it has an effect because 20>10."
10 ERROR "This is the final line ten. The previous GOTO 10 won't find it because line 20 comes first."
10
15
20 
0 PRINT "This program examines how"
1 PRINT "Model T computers run"
2 PRINT "degenerate tokenized BASIC."
3 PRINT "Trying to load it as a .DO"
4 PRINT "file will not work as"
5 PRINT "Tandy BASIC corrects issues"
6 PRINT "such as duplicate line numbers"
7 PRINT "and out of order lines."
8 PRINT "Please use hackerb9's"
9 PRINT "pre-tokenized GOTO10.BA."

To run this on a Model 100, download GOTO10.BA which was created using m100-tokenizer.

Miscellaneous notes

• Tokenized BASIC files are binary files, not ASCII and as such cannot be transferred easily using the builtin TELCOM program or the LOAD "COM:" or SAVE "COM:" commands. Instead, one must use a program such as TEENY which can transfer 8-bit data.

• Line endings in the input file can either be CRLF (standard for a Model 100 text document) or simply LF (UNIX style).

• Even when the tokenized format is the same, there exist a multitude of filename extensions to signify to users that a program is intended to run on a certain platform and warn that it may use system specific features.

  Conventions for filename extensions vary. Here are just some of them:

  • .DO This is the extension the Model 100 uses for plain text BASIC files, but in general can mean any ASCII text document with CRLF line endings.

  • .BA All tokenized BASIC programs are named .BA on the Model 100, but note that most .BA files found on the Internet are in ASCII format. Before the existence of tokenizers like this, one was expected to know that ASCII files had to be renamed to .DO when downloading to a Model 100.

  • Although the BASIC language and tokenization is the same, some programs use POKEs or CALLs which work only one one model of portable computer and will cause others to crash badly, possibly losing files. To avoid this, some filename extensions are used:

  • .100 An ASCII BASIC file that includes POKEs or CALLs specific to the Model 100/102.

  • .200 An ASCII BASIC file specific to the Tandy 200.

  • .BA1 A tokenized BASIC file specific to the Model 100/102.

  • .BA2 A tokenized BASIC file specific to the Tandy 200.

  • The .BA0 and .NEC.BA extension signify a tokenized BASIC file specific to the NEC portables. This is a different tokenization format than any of the above and is not yet supported.

• To save in ASCII format on the Model 100, append , A:

  save "FOO", A

Testing

Run make check to try out the tokenizer on some sample Model 100 programs and some strange ones designed specifically to exercise peculiar syntax. The program bacmp is used to compare the generated .BA file with one created on hackerb9's Tandy 200.

Note that without m100-sanity, the SCRAMB.DO test, whose input is scrambled and redundant, would fail.

20 GOTO 10
10 GOTO 10
10 PRINT "!dlroW ,olleH"

bacmp: BASIC comparator

The included bacmp.c program may be useful for others who wish to discover if two tokenized BASIC files are identical. Because of the way the Model 100 works, a normal cmp test will fail. There are pointers from each BASIC line to the next which change based upon where the program happens to be in memory. The bacmp program handles that by allowing line pointers to differ as long as they are offset by a constant amount.

Note that generating correct line pointers is actually unnecessary in a tokenizer; they could be any arbitrary values. The Model 100 always regenerates the pointers when it loads a .BA file. However, some emulators insist on having them precisely correct, so this tokenizer has followed suit.

More information

• Hackerb9 has documented the file format of tokenized BASIC at http://fileformats.archiveteam.org/wiki/Tandy_200_BASIC_tokenized_file

Alternatives

Here are some other ways that you can tokenize Model 100 BASIC when the source code and the tokenized version won't both fit in the M100's RAM.

• Perhaps the simplest is to load the ASCII BASIC file to the M100 over a serial port from a PC host. On the Model 100, type:

      LOAD "COM:88N1"
  

  or for a Tandy 200, type

      LOAD "COM:88N1ENN"
  

  On the host side, send the file followed by the ^Z ('\x1A') character to signal End-of-File. See hackerb9's sendtomodelt for a script to make this easier.

• Robert Pigford wrote a Model 100 tokenizer that runs in Microsoft Windows. Includes PowerBASIC source code. http://www.club100.org/memfiles/index.php?&direction=0&order=nom&directory=Robert%20Pigford/TOKENIZE

• Mike Stein's entoke.exe is a tokenizer for Microsoft DOS. http://www.club100.org/memfiles/index.php?&direction=0&order=nom&directory=Mike%20Stein

• The Model 100's ROM disassembly shows that the tokenization code is quite short. http://www.club100.org/memfiles/index.php?action=downloadfile&filename=m100_dis.txt&directory=Ken%20Pettit/M100%20ROM%20Disassembly

• The VirtualT emulator can be scripted to tokenize a program through telnet. https://sourceforge.net/projects/virtualt/