diff --git a/src/emu/sound/discrete.h b/src/emu/sound/discrete.h
index 4ce2dbc6f82..29c88358192 100644
--- a/src/emu/sound/discrete.h
+++ b/src/emu/sound/discrete.h
@@ -840,6 +840,36 @@
  *
  * EXAMPLES: see Polaris, Amazing Maze
  *
+ *          --------------------------------------------------
+ *
+ *     DISC_OP_AMP_OSCILLATOR_2 | DISC_OP_AMP_IS_NORTON
+ *          Basic Norton Op Amp Oscillator circuit.
+ *
+ *       .-------------------------------------------> DISC_OP_AMP_OSCILLATOR_OUT_CAP
+ *       |
+ *       |       r1
+ *       +------ZZZZ-----.
+ *       |               |
+ *       |         |\    |
+ *       |    r2   | \   |
+ *       +---ZZZZ--|- \  |
+ *       |         |   >-+-------> DISC_OP_AMP_OSCILLATOR_OUT_SQW
+ *      ---        |+ /  |
+ *      ---    .---| /   |
+ *       |     |   |/    |
+ *      gnd    |         |
+ *             |   r3    |
+ *             +--ZZZZ---'
+ *             |
+ *             Z
+ *             Z r4
+ *             Z
+ *             |
+ *             ^
+ *             vP
+ *
+ * EXAMPLES: see Space Walk
+ *
  ***********************************************************************
  *
  * DISCRETE_OP_AMP_VCOn - Various single power supply op-amp VCO circuits
diff --git a/src/mame/audio/mw8080bw.c b/src/mame/audio/mw8080bw.c
index 20a2e28cfcd..939dc0b0b02 100644
--- a/src/mame/audio/mw8080bw.c
+++ b/src/mame/audio/mw8080bw.c
@@ -2141,7 +2141,7 @@ DISCRETE_OP_AMP_TRIG_VCA(NODE_RELATIVE(NODE_35, _num),				/* IC M2-3, pin 9 */
 	NODE_RELATIVE(NODE_33, _num), 0,								/* IN0, IN1 */          \
 	&spacwalk_sb_hit_tvca_info)                                                             \
 /* Wrong values.  Untested */                                                               \
-/* The rest of the circuit is a filter.                                                     \
+/* The rest of the circuit is a filter. */                                                  \
 DISCRETE_FILTER2(NODE_RELATIVE(NODE_37, _num),                                              \
 	1,												/* ENAB */                              \
 	NODE_RELATIVE(NODE_35, _num),					/* INP0 */                              \