mirror of
https://github.com/hsoft/collapseos.git
synced 2024-12-28 14:48:05 +11:00
47 lines
1.3 KiB
Markdown
47 lines
1.3 KiB
Markdown
# BASIC as a shell
|
|
|
|
This recipe demonstrate the replacement of the usual shell with the BASIC
|
|
interpreter supplied in Collapse OS. To make things fun, we play with I/Os
|
|
using RC2014's Digital I/O module.
|
|
|
|
## Gathering parts
|
|
|
|
* Same parts as in the base recipe
|
|
* (Optional) RC2014's Digital I/O module
|
|
|
|
The Digital I/O module is only used in the example BASIC code. If you don't
|
|
have the module, just use BASIC in another fashion.
|
|
|
|
## Build the image
|
|
|
|
As usual, building `os.bin` is a matter of running `make`. Then, you can get
|
|
that image to your EEPROM like you did in the base recipe.
|
|
|
|
## Usage
|
|
|
|
Upon boot, you'll directy be in a BASIC prompt. See documentation in
|
|
`apps/basic/README.md` for details.
|
|
|
|
For now, let's have some fun with the Digital I/O module. Type this:
|
|
|
|
```
|
|
> a=0
|
|
> 10 out 0 a
|
|
> 20 sleep 0xffff
|
|
> 30 a=a+1
|
|
> 40 goto 10
|
|
> run
|
|
```
|
|
|
|
You now have your Digital I/O lights doing a pretty dance, forever.
|
|
|
|
## Looking at the glue code
|
|
|
|
If you look at the glue code, you'll see that it's very similar to the one in
|
|
the base recipe, except that the shell includes have been replaced by the basic
|
|
includes. Those includes have been copy/pasted from `apps/basic/glue.asm` and
|
|
`USER_RAMSTART` has been replaced with `STDIO_RAMEND` so that BASIC's memory
|
|
gets placed properly (that is, right after the kernel's memory).
|
|
|
|
Simple, isn't it?
|