Apple-1-Tools/apple1-videocard-lib
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@ -1,17 +1,17 @@
# apple1-videocard-lib
Library and demos for the "Apple-1 Graphic Card" by P-LAB,
featuring the TMS9918 Video Display Processo by Texas Instruments.
featuring the TMS9918 Video Display Processor by Texas Instruments.
## Repo structure
```
demo a demo program that makes use of the library
docs TMS9918 and Apple1 manuals
kickc target configuration files for KickC
lib the library files to include in your project
tetris a demo game
tools some build tools
demo/ a demo program that makes use of the library
docs/ TMS9918 and Apple-1 manuals
kickc/ target configuration files for KickC
lib/ the library files to include in your project
tetris/ a demo game
tools/ some build tools
```
## Introduction
@ -22,12 +22,11 @@ with the "Apple-1 Graphic Card" board by [P-LAB]() or any
other video card that maps the TMS9918 in the `$CC00`-`$CC01`
memory range of the Apple-1.
The library is written in C with [KickC](https://gitlab.com/camelot/kickc/-/releases)
which is a very efficient 6502 C compiler.
The library is written in C with [KickC](https://gitlab.com/camelot/kickc/-/releases), a very efficient 6502 C compiler.
## Choice of the screen mode
The library only supports screen modes 1 and 2 (screen 0 and screen 3 not
The library supports screen modes 1 and 2 only (screen 0 and screen 3 not
being very useful). Both are 256x192 pixels but there are some differences
you should consider when evaluating which mode to use:
@ -115,7 +114,7 @@ screen2_puts(16, 12, col, "HELLO");
Some example code:
```c
// writes the value 42 at the VRAM location 8000
// writes the value 42 at VRAM location 8000
tms_set_vram_write_addr(8000);
TMS_WRITE_DATA_PORT(42);
@ -125,7 +124,7 @@ byte val = TMS_READ_DATA_PORT;
```
When using the default values that came with `SCREEN1_TABLE[]` and `SCREEN2_TABLE[]`,
the VRAM is organized according the following memory map:
VRAM is organized according the following memory map:
```c
// ZONE RANGE NAME YOU CAN USE IN C
// ===========================================================
@ -200,35 +199,35 @@ from the `lib/` directory in your C source files.
Compile your sources with the KickC compiler, the `tools/`
directory contains a `build.bat` script example for Windows.
There are three configurations you can target with the KickC
compiler switches `-t target -targetdir thisrepopath/kickc`:
There are three configurations you can target with the switches `-t target -targetdir thisrepopath/kickc` of the KickC compiler:
- apple1
- apple1_jukebox
- vic20
- `apple1`
- `apple1_jukebox`
- `vic20`
#### Target "apple1"
With this target, the compiled program will start at `$280` in
the free RAM on the Apple-1 (please make sure you have enough RAM).
With this target, the compiled program will start at `$0280` in
the free RAM of the Apple-1 (please make sure you have enough RAM).
TODO: add reference to `hexdump.js`
(TODO: add reference to `hexdump.js`)
#### Target "apple1_jukebox"
This target is for expansion Cards that provide a ROM storage in
This target is for expansion cards that provide a ROM storage in
the range `$4000`-`$7FFF`, as:
- the "CodeTank" EEPROM daughterboard of the "Apple-1 Graphic Card"
- "Juke-Box Card" FLASH
In this target configuration, the program is split into two segments:
- the "Code" that resides in ROM at `$4000`
- the "Data" that resides in RAM at `$0280`
(this because the program needs to change the "Data").
- the `Code` that resides in ROM at `$4000`
- the `Data` that resides in RAM at `$0280`
The split is required because the program needs to write on the `Data` segment (e.g. when changing the value of a variable).
The only issue is that the "Data" segment needs to be initialized
with the startup values (for example, the value that a global `int` variable
takes before it's used).
with the correct startup values (for example, the value that
a global `int` variable takes before it's used).
The "Data" initialization needs to be done manually in the C program
by explicitly calling `apple1_eprom_init()` in `main()`. The function