diff --git a/recipes/sms/romasm/.gitignore b/recipes/sms/romasm/.gitignore
new file mode 100644
index 0000000..2e334fc
--- /dev/null
+++ b/recipes/sms/romasm/.gitignore
@@ -0,0 +1 @@
+user.h
diff --git a/recipes/sms/romasm/Makefile b/recipes/sms/romasm/Makefile
new file mode 100644
index 0000000..8be033e
--- /dev/null
+++ b/recipes/sms/romasm/Makefile
@@ -0,0 +1,18 @@
+ZASM = ../../../tools/zasm.sh
+KERNEL = ../../../kernel
+APPS = ../../../apps
+
+.PHONY: all
+all: os.sms ed.bin
+
+ed.bin: $(APPS)/ed/glue.asm
+	echo ".equ USER_CODE ED_CODE" | cat user-tmpl.h - > user.h
+	$(ZASM) $(KERNEL) $(APPS) user.h < $< > $@
+
+zasm.bin: $(APPS)/zasm/glue.asm
+	echo ".equ USER_CODE ZASM_CODE" | cat user-tmpl.h - > user.h
+	$(ZASM) $(KERNEL) $(APPS) user.h < $< > $@
+
+os.sms: glue.asm ed.bin zasm.bin
+	$(ZASM) $(KERNEL) ed.bin zasm.bin < $< > $@
+
diff --git a/recipes/sms/romasm/README.md b/recipes/sms/romasm/README.md
new file mode 100644
index 0000000..b66a8c4
--- /dev/null
+++ b/recipes/sms/romasm/README.md
@@ -0,0 +1,15 @@
+# zasm and ed from ROM
+
+SMS' RAM is much tighter than in the RC2014, which makes the idea of loading
+apps like zasm and ed in memory before using it a bit wasteful. In this recipe,
+we'll include zasm and ed code directly in the kernel and expose them as shell
+commands.
+
+Moreover, we'll carve ourselves a little 1K memory map to put a filesystem in
+there. This will give us a nice little system that can edit small source files
+compile them and run them.
+
+## Gathering parts
+
+* A SMS that can run Collapse OS.
+* A [PS/2 keyboard adapter](../kbd/README.md)
diff --git a/recipes/sms/romasm/glue.asm b/recipes/sms/romasm/glue.asm
new file mode 100644
index 0000000..1caf235
--- /dev/null
+++ b/recipes/sms/romasm/glue.asm
@@ -0,0 +1,151 @@
+; 8K of onboard RAM
+.equ	RAMSTART	0xc000
+; Memory register at the end of RAM. Must not overwrite
+.equ	RAMEND		0xddd0
+
+	jp	init
+
+; *** JUMP TABLE ***
+	jp	strncmp
+	jp	addDE
+	jp	addHL
+	jp	upcase
+	jp	unsetZ
+	jp	intoDE
+	jp	intoHL
+	jp	writeHLinDE
+	jp	findchar
+	jp	parseHex
+	jp	parseHexPair
+	jp	blkSel
+	jp	blkSet
+	jp	fsFindFN
+	jp	fsOpen
+	jp	fsGetC
+	jp	fsPutC
+	jp	fsSetSize
+	jp	cpHLDE
+	jp	parseArgs
+	jp	printstr
+	jp	_blkGetC
+	jp	_blkPutC
+	jp	_blkSeek
+	jp	_blkTell
+	jp	printcrlf
+	jp	stdioPutC
+	jp	stdioReadLine
+
+.fill 0x66-$
+	retn
+
+#include "err.h"
+#include "core.asm"
+#include "parse.asm"
+
+#include "sms/kbd.asm"
+.equ	KBD_RAMSTART	RAMSTART
+.equ	KBD_FETCHKC	smskbdFetchKCB
+#include "kbd.asm"
+
+.equ	VDP_RAMSTART	KBD_RAMEND
+#include "sms/vdp.asm"
+
+.equ	STDIO_RAMSTART	VDP_RAMEND
+#include "stdio.asm"
+
+.equ	MMAP_START	0xd800
+#include "mmap.asm"
+
+.equ	BLOCKDEV_RAMSTART	STDIO_RAMEND
+.equ	BLOCKDEV_COUNT		3
+#include "blockdev.asm"
+; List of devices
+.dw	mmapGetC, mmapPutC
+.dw	f0GetC, f0PutC
+.dw	f1GetC, f1PutC
+
+#include "blockdev_cmds.asm"
+
+.equ	FS_RAMSTART	BLOCKDEV_RAMEND
+.equ	FS_HANDLE_COUNT	2
+#include "fs.asm"
+#include "fs_cmds.asm"
+
+.equ	SHELL_RAMSTART	FS_RAMEND
+.equ	SHELL_EXTRA_CMD_COUNT 11
+#include "shell.asm"
+.dw	edCmd, zasmCmd, fnewCmd, fdelCmd, fopnCmd, flsCmd, fsOnCmd, blkBselCmd
+.dw	blkSeekCmd, blkLoadCmd, blkSaveCmd
+
+init:
+	di
+	im	1
+
+	ld	sp, RAMEND
+
+	; init a FS in mmap
+	ld	hl, MMAP_START
+	ld	a, 'C'
+	ld	(hl), a
+	inc	hl
+	ld	a, 'F'
+	ld	(hl), a
+	inc	hl
+	ld	a, 'S'
+	ld	(hl), a
+	call	fsInit
+	xor	a
+	call	blkSel
+
+	call	kbdInit
+	call	vdpInit
+
+	ld	hl, kbdGetC
+	ld	de, vdpPutC
+	call	stdioInit
+	call	shellInit
+	jp	shellLoop
+
+f0GetC:
+	ld	ix, FS_HANDLES
+	jp	fsGetC
+
+f0PutC:
+	ld	ix, FS_HANDLES
+	jp	fsPutC
+
+f1GetC:
+	ld	ix, FS_HANDLES+FS_HANDLE_SIZE
+	jp	fsGetC
+
+f1PutC:
+	ld	ix, FS_HANDLES+FS_HANDLE_SIZE
+	jp	fsPutC
+
+edCmd:
+	.db	"eded", 0b1001, 0, 0
+	push	hl \ pop ix
+	ld	l, (ix)
+	ld	h, (ix+1)
+	jp	0x1800
+
+zasmCmd:
+	.db	"zasm", 0b1001, 0, 0
+	push	hl \ pop ix
+	ld	l, (ix)
+	ld	h, (ix+1)
+	jp	0x1c00
+
+; last time I checked, PC at this point was 0x175a. Let's give us a nice margin
+; for the start of ed.
+.fill 0x1800-$
+.bin "ed.bin"
+
+; Last check: 0x1b4e
+.fill 0x1c00-$
+.bin "zasm.bin"
+
+.fill 0x7ff0-$
+.db "TMR SEGA", 0x00, 0x00, 0xfb, 0x68, 0x00, 0x00, 0x00, 0x4c
+
+
diff --git a/recipes/sms/romasm/user-tmpl.h b/recipes/sms/romasm/user-tmpl.h
new file mode 100644
index 0000000..1f9e8fa
--- /dev/null
+++ b/recipes/sms/romasm/user-tmpl.h
@@ -0,0 +1,37 @@
+; USER_CODE is filled in on-the-fly with either ED_CODE or ZASM_CODE
+.equ    ED_CODE         0x1800
+.equ    ZASM_CODE       0x1c00
+.equ    USER_RAMSTART   0xc200
+.equ    FS_HANDLE_SIZE  6
+.equ    BLOCKDEV_SIZE   8
+
+; *** JUMP TABLE ***
+.equ	strncmp			0x03
+.equ	addDE			0x06
+.equ	addHL			0x09
+.equ	upcase			0x0c
+.equ	unsetZ			0x0f
+.equ	intoDE			0x12
+.equ	intoHL			0x15
+.equ	writeHLinDE		0x18
+.equ	findchar		0x1b
+.equ	parseHex		0x1e
+.equ	parseHexPair	0x21
+.equ	blkSel			0x24
+.equ	blkSet			0x27
+.equ	fsFindFN		0x2a
+.equ	fsOpen			0x2d
+.equ	fsGetC			0x30
+.equ	fsPutC			0x33
+.equ	fsSetSize		0x36
+.equ	cpHLDE			0x39
+.equ	parseArgs		0x3c
+.equ	printstr		0x3f
+.equ	_blkGetC		0x42
+.equ	_blkPutC		0x45
+.equ	_blkSeek		0x48
+.equ	_blkTell		0x4b
+.equ	printcrlf		0x4e
+.equ	stdioPutC		0x51
+.equ	stdioReadLine	0x54
+