Emu-Writer

A Word Process for a TI-99/4a

My own attempt at a word processor for the TI-99/4a. The goal of this project is to understand how a word processor would be written on older technology. It's fun to imagine that it will be better than TI-Writter/Word-Processor, but it's not going to be better than a product available to you to run in Windows or Linux. This project is a strange form of fun and a vanity project, not something that is practical.

Emu-writer distinguishes itself from TI-Writer with the following featues.

• When you wish to insert text into the middle of a paragraph, just move the cursor to the desired location and start typing. No need to press FCTN+2 followed by CTRL+2
• FCTN+3 is used as a backspace-delete key.
• FCTN+0 is used to switch between Vertical mode and Windowed mode.
  • Windowed mode works the same as TI-Writer; when paragraphs will be more than 40 characters wide on paper, it is necessary for the screen to move to the left or right within a page.
  • Vertical mode assumes that a user wants to read text from the screen. On screen, the wrap algorithm assumes a paragraph width of 39 characters, even though the printed document will have wider paragraphs.
  • It is not necessary to switch modes before printing. The print algorithm automatically wraps the paragraphs for 80-columns.
  • I realize that this is possible in TI-Writer, but that program makes it less intuitive. The user has to know how to wield the Editor's margin-and-tab configuration in a way that is complemented by the Formater program.

External Dependencies

MEMBUF.noheader.obj and ARRAY.noheader.obj - Source code can be found at the repo: https://github.com/bkrug/TI-string-buffer. These contain routines for allocating and de-allocating space for variable-length objects like strings and arrays.

Assembling

• Python is required.
• XDT99 is required. (https://endlos99.github.io/xdt99/)
• Run the script "assm.py" and it will assemble the main program and the test programs.
  • Have Python and XDT99 included in your system's Path. The script is setup assuming that you can type "xas99.py" from a command line without specifying a folder.

Finding the path to Python

In your Python interpreter, type the following commands:

import os
import sys
os.path.dirname(sys.executable)

Running Python Scripts from Powershell

First, add the xas99 folder to your System PATH variables.

Then, associate *.py files with python. Run the following commands at a shell prompt:

assoc .py=PythonScript
ftype PythonScript=C:\bin\python.exe "%1" %*

Assembly Results

• Assembled code is placed in two places:
  • "Fiad" folder. You will be able to see each individual program as a file with the TIFILES header.
  • "EmuWriter.dsk" image in the root folder
• the EMUWRITER program is run as an E/A 5 program
• the unit test programs (which have the suffix RUN.obj) are run as E/A 3 programs.
  • Use the program name "RUNTST".
  • Someday it would be nice to be able to run all unit tests as a single program, but for now you need to run each group of tests individualy.
• You might wonder why the EMUWRITER program is followed by so many other E/A 5 programs like EMUWRITES. This has to do with how the program is stored in RAM after loading it from a disk.
  • EMUWRITER is stored at address >2000 and occupies 6 KB.
  • The other EMUWRITE* programs are intially loaded into VDP RAM. Each of them can be pulled into the 2KB space at address >3800, when there is a need to execute them.
  • This design is meant to reserve the upper 24 KB of the TI-99's expansion RAM for the user's document. The executable code is starting to grow beyond the lower 8 KB of the expansion RAM.

Taglines

EMU-WRITER -- A semi-modern word processor for a semi-modern world.

EMU-WRITER -- Be a little late to the party.

EMU-WRITER -- WYSIWhaaaaaat?

EMU-WRITER -- You didn't think you needed it, but now you know.

TODO

• When creating the disk image, write-protect the program files.
• When splitting a paragraph, the "new" paragraph should always be the smaller of the two. This makes memory management easier.
• Consider adding a defrag operation that runs every 64/60s seconds.
• The save routine appears to ignore write-protection status. Use the PAB's STATUS op-code in order to fix that, or alternatively, simply refuse to overwrite any file that is not DSP/FIX 64.

Manual test cases

• When the memeory is full, do the following and confirm that there are no graphical problems:
  • When the system cannot let you split paragraphs using the enter key, the document should not change.
  • When the system cannot let you merge paragraphs using the delete key, the document should not change.
  • When the system cannot let you insert new characters in an existing paragrahp, the document should stop changing.
• Load the file "BIG". Press enter many times from the end of the document. When the memory is full, the cursor stops blinking. Scroll up to the non-blank line, and it blinks again. Scroll back down to the last empty line and it stops blinking again.