recipes/rc2014/basic: new recipe

recipes/rc2014/README.md

@@ -27,6 +27,7 @@ are other recipes related to the RC2014:
 * [Accessing a MicroSD card](sdcard/README.md)
 * [Assembling binaries](zasm/README.md)
 * [Interfacing a PS/2 keyboard](ps2/README.md)
+* [Replace shell by a BASIC interpreter](basic/README.md)
 
 ## Recipe
 

recipes/rc2014/basic/Makefile

@@ -0,0 +1,10 @@
+TARGET = os.bin
+ZASM = ../../../tools/zasm.sh
+KERNEL = ../../../kernel
+APPS = ../../../apps
+
+.PHONY: all
+all: $(TARGET)
+$(TARGET): glue.asm
+	$(ZASM) $(KERNEL) $(APPS) < $< > $@
+

recipes/rc2014/basic/README.md

@@ -0,0 +1,46 @@
+# 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+the base recipe, except that the shell includes have been replaced by the basic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?

recipes/rc2014/basic/glue.asm

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+.equ	RAMSTART	0x8000
+.equ	RAMEND		0xffff
+.equ	ACIA_CTL	0x80	; Control and status. RS off.
+.equ	ACIA_IO		0x81	; Transmit. RS on.
+.equ	DIGIT_IO	0x00	; digital I/O's port
+
+jp	init
+
+; interrupt hook
+.fill	0x38-$
+jp	aciaInt
+
+.inc "err.h"
+.inc "ascii.h"
+.inc "core.asm"
+.inc "str.asm"
+.equ	ACIA_RAMSTART	RAMSTART
+.inc "acia.asm"
+
+.equ	STDIO_RAMSTART	ACIA_RAMEND
+.equ	STDIO_GETC	aciaGetC
+.equ	STDIO_PUTC	aciaPutC
+.inc "stdio.asm"
+
+; *** BASIC ***
+
+; RAM space used in different routines for short term processing.
+.equ	SCRATCHPAD_SIZE	0x20
+.equ	SCRATCHPAD	STDIO_RAMEND
+.inc "lib/util.asm"
+.inc "lib/ari.asm"
+.inc "lib/parse.asm"
+.inc "lib/fmt.asm"
+.equ	EXPR_PARSE	parseLiteralOrVar
+.inc "lib/expr.asm"
+.inc "basic/util.asm"
+.inc "basic/parse.asm"
+.inc "basic/tok.asm"
+.equ	VAR_RAMSTART	SCRATCHPAD+SCRATCHPAD_SIZE
+.inc "basic/var.asm"
+.equ	BUF_RAMSTART	VAR_RAMEND
+.inc "basic/buf.asm"
+.equ	BAS_RAMSTART	BUF_RAMEND
+.inc "basic/main.asm"
+
+init:
+	di
+	; setup stack
+	ld	sp, RAMEND
+	im 1
+
+	call	aciaInit
+	ei
+	jp	basStart
+
+