I did not modify cdev_decl(); I put the prototype in the header <sys/scan.h>

--- conf.c.DIST	Wed Jun 15 06:24:23 1994
+++ conf.c	Tue Jan 31 21:44:08 1995
@@ -34,6 +34,7 @@
 #include <sys/buf.h>
 #include <sys/ioctl.h>
 #include <sys/tty.h>
+#include <sys/scan.h>
 #include <sys/conf.h>
 #include <sys/vnode.h>
 
@@ -99,6 +100,7 @@
 #include "wt.h"
 #include "sd.h"
 #include "st.h"
+#include "sj.h"
 #include "cd.h"
 #include "mcd.h"
 #include "vn.h"
@@ -166,6 +168,15 @@
 	(dev_type_reset((*))) nullop, 0, seltrue, (dev_type_mmap((*))) enodev, \
 	dev_init(c,n,strategy) }
 
+/* open, close, read, ioctl, strategy */
+cdev_decl(sj);
+#define	cdev_sj_init(c,n) { \
+	dev_init(c,n,open), dev_init(c,n,close), rawsjread, \
+        (dev_type_write((*))) enodev, \
+	dev_init(c,n,ioctl), (dev_type_stop((*))) enodev, \
+	(dev_type_reset((*))) nullop, 0, seltrue, (dev_type_mmap((*))) enodev, \
+	dev_init(c,n,strategy) }
+
 /* open, close, read, write, ioctl, stop, tty */
 #define	cdev_tty_init(c,n) { \
 	dev_init(c,n,open), dev_init(c,n,close), dev_init(c,n,read), \
@@ -379,7 +390,7 @@
 	cdev_disk_init(NCD,cd),		/* 15: SCSI CD-ROM */
 	cdev_lpt_init(NLPT,lpt),	/* 16: parallel printer */
 	cdev_ch_init(NCH,ch),		/* 17: SCSI autochanger */
-	cdev_notdef(),			/* 18: unused */
+	cdev_sj_init(NSJ,sj),		/* 18: SCSI scanner */
 	cdev_notdef(),			/* 19: unused */
 	cdev_notdef(),			/* 20: unused */
 	cdev_notdef(),			/* 21: unused */