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