diff --git a/src/mame/fidelity/vcc.cpp b/src/mame/fidelity/vcc.cpp
index 495dd5d298a..476086b8110 100644
--- a/src/mame/fidelity/vcc.cpp
+++ b/src/mame/fidelity/vcc.cpp
@@ -3,12 +3,12 @@
 /******************************************************************************
 
 Fidelity Voice Chess Challenger series hardware
-- Voice Chess Challenger (VCC) (version A and B?)
+- Voice Chess Challenger (VCC) (2 revisions)
 - Advanced Voice Chess Challenger (UVC)
-- *Grandmaster Voice Chess Challenger (Fidelity Deutschland product)
-- *Decorator Challenger (FCC)
+- Grandmaster Voice Chess Challenger (Fidelity Deutschland product)
+- Decorator Challenger (FCC)
 
-*: not dumped yet
+Grandmaster and FCC are verified to be the same PCB + ROMs as UVC.
 
 *******************************************************************************
 
@@ -28,7 +28,7 @@ number, but the contents are identical.
 
 Memory map (VCC):
 -----------
-0000-0FFF: 4K 2332 ROM 101-32013
+0000-0FFF: 4K 2332 ROM VCC1 or 101-32013
 1000-1FFF: 4K 2332 ROM VCC2
 2000-2FFF: 4K 2332 ROM VCC3
 4000-5FFF: 1K RAM (2114 SRAM x2)
diff --git a/src/mame/handheld/chessking.cpp b/src/mame/handheld/chessking.cpp
index d736b84712e..88f1b00e944 100644
--- a/src/mame/handheld/chessking.cpp
+++ b/src/mame/handheld/chessking.cpp
@@ -168,8 +168,8 @@ void chessking_state::beeper_enable_w(uint8_t data)
 void chessking_state::update_beeper()
 {
 	uint16_t freq = (~m_beeper_freq & 0x1ff) + 1;
-	double step = (9.6_MHz_XTAL).dvalue() / 0x200000;
-	m_beeper->set_clock(freq * step);
+	double base = (9.6_MHz_XTAL).dvalue() / 0x80;
+	m_beeper->set_clock(base / freq);
 }
 
 
diff --git a/src/mame/handheld/hh_hmcs40.cpp b/src/mame/handheld/hh_hmcs40.cpp
index 591dce5ad0b..12c4c222019 100644
--- a/src/mame/handheld/hh_hmcs40.cpp
+++ b/src/mame/handheld/hh_hmcs40.cpp
@@ -81,7 +81,7 @@ known chips:
   C57     HD44801  1985, Alpha 8505 protection MCU (see 8201)
   C89     HD44801  1985, CXG Portachess (1985 version) -> cxg/scptchess.cpp
 
- *A86     HD44820  1983, Chess King Pocket Micro
+ *A86     HD44820  1983, Chess King Pocket Micro / Mighty Midget
  *B63     HD44820  1985, CXG Pocket Chess (12 buttons)
 
  *A13     HD44840  1982, CXG Computachess II
@@ -107,7 +107,7 @@ ROM source notes when dumped from another title, but confident it's the same:
 - zackman: Tandy Zackman
 
 TODO:
-- cgalaxn discrete sound (alien attacking sound effect)
+- cgalaxn netlist sound for alien attack sweep sound (MAME doesn't support N13T1?)
 - epacman2 booting the game in demo mode, pacman should take the shortest route
   to the upper-left power pill, followed by going to the top-right power pill:
   mcu cycle/interrupt timing related
diff --git a/src/mame/handheld/nl_bship.cpp b/src/mame/handheld/nl_bship.cpp
index 4857e2f032c..f7466602293 100644
--- a/src/mame/handheld/nl_bship.cpp
+++ b/src/mame/handheld/nl_bship.cpp
@@ -7,6 +7,8 @@ Milton Bradley Electronic Battleship model 4750A (hh_tms1k.cpp)
 
 TODO:
 - OPENDRAIN parameters are not fully known
+- DYNAMIC_MIN_TIMESTEP 1e-6 is a bit better, but too taxing for MAME,
+  maybe it could be made faster with OPTIMIZE_FRONTIER
 - Q2 should be a 2N3703 (same, just different max voltage)
 - D6 should be a 1K60? (germanium, type unknown, but looks like 1K60)
 - move 1N754A to netlist library?
diff --git a/src/mame/handheld/nl_sfxphasor.cpp b/src/mame/handheld/nl_sfxphasor.cpp
index bb10da2279a..101af4bfb24 100644
--- a/src/mame/handheld/nl_sfxphasor.cpp
+++ b/src/mame/handheld/nl_sfxphasor.cpp
@@ -4,7 +4,7 @@
 /*
 
 Electroplay Sound FX Phasor (hh_pic16.cpp)
-3-bit sound with volume envelope
+3-bit sound (standard) + volume envelope
 
 TODO:
 - transistors should be BC183
@@ -18,6 +18,7 @@ NETLIST_START(sfxphasor)
 {
 	SOLVER(Solver, 48000)
 	PARAM(Solver.ACCURACY, 1e-7)
+
 	ANALOG_INPUT(VBATT, 5)
 
 	NET_MODEL("OPENDRAIN FAMILY(TYPE=MOS OVL=0.4 OVH=2.4 ORL=1.0 ORH=1e12)")