Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/ckormanyos/ti84-ref_app

TI-84 Plus reference application
https://github.com/ckormanyos/ti84-ref_app

sdcc-compiler ti-84-plus z80 z80-asm

Last synced: about 1 month ago
JSON representation

TI-84 Plus reference application

Awesome Lists containing this project

README 

        
ti84-ref_app

==================





    

        build

    

        Issues

    

        Unlicense




`ckormanyos/ti84-ref_app` creates a fully functioning reference application

for the TI-84 Plus monochrome graphics calculator. It runs in the

open `Asm(prgm)` interface provided in the calculator's `CATALOG` menu.

It uses the TI-84's on-board [Z80 processor](https://en.wikipedia.org/wiki/Zilog_Z80).



The reference application implements parallel _blinky_ and _hello_-_world_ text sequences.

It boots through a small startup code and subsequently

initializes a skinny microcontroller abstraction layer (MCAL).

Control is then passed to a minimalistic cooperative multitasking scheduler.

The application task (managed by the scheduler) directs the presentations

of its associated ASCII-text messages.



The text sequences _ON_/_OFF_ and _hello_/_world_ are presented in

cyclic, alternating fashion(s) on the calculator screen.

Text is used since there is no actual LED present on the calculator-target system.

This is intended to simulate an LED-blinky by _toggling_ between _ON_ and _OFF_.

To make the program a little more interesting, an independent _hello_-_world_-task

is supported as well. The _ON_/_OFF_ messages are printed every $1s$

and the _hello_/_world_ messages every $3s$.



## Implementation details



The cooperative multitasking timebase is derived from a $1s$ tick.

The underlying $32$-bit timer resides on ports `0x45`-`0x48`,

where the lower byte at port `0x45` is used.

This timer is only available on the TI-84, not the TI-83.



The blinky _ON_/_OFF_ and _hello_/_world_ text messages are printed

at rows $2$ and $3$, respectively, and both at column $6$.



A skinny `main()` subroutine in the soruce file

[`app_main.c`](./src/app/app_main.c) controls the program flow.

After starting the multitasking scheduler with

[`os_schedule()`](https://github.com/ckormanyos/ti84-ref_app/blob/8291393f971d234c3493e18589b60421d22f61cc/src/app/app_main.c#L27),

it services the two alternating tasks

[`app_led_task()`](https://github.com/ckormanyos/ti84-ref_app/blob/8291393f971d234c3493e18589b60421d22f61cc/src/app/app_led.c#L10)

and

[`app_hello_task()`](https://github.com/ckormanyos/ti84-ref_app/blob/8291393f971d234c3493e18589b60421d22f61cc/src/app/app_hello.c#L10)

based on their cycle times.



The application is written in the C language using the C23 standard.

There is minimal use of assembly for startup and to interface with

[TI-83 Plus System Routines](https://education.ti.com/html/eguides/discontinued/computer-software/EN/SDK-TI-83-System-Routines_EN.pdf).



## Running on the Calculator



Programming the calculator:

  - After build, locate `bin/refapp.8xp`.

  - Drag `refapp.8xp` onto the calculator using the standard method with [TI Connect version 4](https://education.ti.com/en/software/details/en/B59F6C83468C4574ABFEE93D2BC3F807/swticonnectsoftware). Important: Use version 4 for the TI-84 Plus.

  - The on-calculator name of the program is `REFAPP`.



To start the program, use the usual `Asm(prgm)` option found in the `CATALOG`

menu and select the `REFAPP` program. The explicit keystrokes are listed below.



Let's execute the program on the calculator using keystrokes:

  - Hit $2^{nd}$-`CATALOG`.

  - Use the arrows to navigate down to the `Asm(` entry.

  - Hit the `ENTER`-key.

  - Then hit the `PRGM`-key.

  - Select `REFAPP` and hit the `ENTER`-key.

  - The calculator screen should now show `Asm(prgmREFAPP`.

  - Hit the `ENTER`-key and the program should start to run.

  - To exit the blinky _ON_/_OFF_ and hello/world show, press the `ENTER`-key.

  - Clear the screen (if desired) with the `CLEAR`-key.



The running programm in the display-state _ON_/_hello_ is shown in the image below.



![](./images/ti84-ref_app.jpg)



## Pre-built Program



A fully-built `ref_app` can be found in the [`bin`](./bin) directory.

This pre-built program can be used to trouble-shoot the environment.



## Tools and Build



This application uses the free

[`sdcc`](https://sdcc.sourceforge.net) toolchain.

C-runtime initialization (i.e., static initialization prior to the call of `main()`)

is supported with the file [crt0.s](./src/startup/crt0.s) in the `startup` directory.



The build system:

  - The build system uses GNUmake with a straighforward [`Makefile`](./build/Makefile).

  - The build system is supported on both `Win*` and `*nix`.

  - The `Win*`-build requires a small selection of ported `*nix` tools. These are included in the [`wbin`](./build/tools/UnxUtils/usr/local/wbin) directory.

  - The on-calculator image is packed by [BinPac8x v1.2](https://www.cemetech.net/news/2010/6/389/_/binpac8x-v12).

  - Build results including HEX-File and the on-calculator image `refapp.8xp` are placed in the `bin`-directory.



### Build on `Win*`



Prerequisites:

  - Install [`sdcc`](https://sdcc.sourceforge.net) version 4.4 or higher.

  - Install python.



Then build in the command shell with:



```cmd

cd ti84-ref_app\build

make all

```



### Build on `*nix`



Prerequisites:

  - Install [`sdcc`](https://sdcc.sourceforge.net) version 4.4 or higher.



Then build in the bash shell with:



```sh

cd ti84-ref_app/build

make all

```



## Testing and Continuous Integration



Testing has been performed on the target system, which is a fully-functioning

TI-84 Plus calculator purchased years ago from a commercial retailer.



Continuous integration is performed on GHA using a ubuntu-latest

and macos-latest runners.

The [workflow run](./.github/workflows/ti84-ref_app.yml)

builds the application and verifies the presence of `bin/refapp.8xp`.



## Aditional Details



### Origins (and Reservations)



  - This project has been inspired by and influenced by numerous previous works, including (but not limited to) the [azertyfun/LibTI](https://github.com/azertyfun/LibTI) project.

  - The aforementioned [project](https://github.com/azertyfun/LibTI) was ground-breaking and excellent.



Please do, however, use this project at your own discretion and observe

also the [license](./LICENSE) details. This project is not in any way

affiliated with Texas Instruments Inc, or any of its subsidiaries,

including the educational products division.



Some of this software has been reverse engineered

from other projects or terse technical notes.

In addition, the software actively writes to calculator

_ports_, such as port `0x40` and port `0x41`.

Personally, I do not consider this to be a $100\\%$ sound basis

for project reliability and/or stability.



Empirical evidence does, nonetheless, show a working,

and fully/properly initialized C-language, non-trivial application.

It provides a basis that seems to adhere to the established,

common rules of modern C. Larger projects could potentially

be built upon or modelled from this one.



### References



  - _TI_-_83_ _Plus_ _System_ _Routines_, Third Release (Jan. 25, 2002), located [here](https://education.ti.com/html/eguides/discontinued/computer-software/EN/SDK-TI-83-System-Routines_EN.pdf)

  - _SDCC_ _Compiler_ _User_ _Guide_, SDCC 4.4.1, Revision 14549 (at the time of writing this doc, Jan. 29, 2024), located [here](https://sdcc.sourceforge.net/doc/sdccman.pdf)



### Licensing



  - The source code written for this repo (in the [`src`](./src)) directory is licensed under [_The_ _Unlicense_](./LICENSE).

  - `Win*`-ported `*nix` tools in [`wbin`](./build/tools/UnxUtils/usr/local/wbin) originate from [UnxTools](https://sourceforge.net/projects/unxutils) and include their own [distribution statements](./build/tools/UnxUtils).

  - The `Win*`-ported GNUmake is taken from [`ckormanyos/make-4.2.1-msvc-build`](https://github.com/ckormanyos/make-4.2.1-msvc-build).