I've used Phil's instructions to set up a build area with a Makefile.

You can run make build from the top to build things.

build/Makefile

@@ -0,0 +1,20 @@
+# Build the kernel, the filesystem and run SimH
+
+AS=../tools/as7
+MKFS=../tools/mkfs7
+SYS=../src/sys
+
+all: a.rim image.fs
+
+run: a.rim image.fs
+	pdp7 unixv0.simh
+
+a.rim:
+	$(AS) -f rim  -o a.rim $(SYS)/sop.s $(SYS)/s[1-8].s
+	$(AS) -f list -o a.lst $(SYS)/sop.s $(SYS)/s[1-8].s
+
+image.fs:
+	$(MKFS) --debug --format simh proto
+
+clean:
+	rm -f a.rim image.fs a.lst