diff --git a/Source/Apps/Test/ps2info/ps2info.asm b/Source/Apps/Test/ps2info/ps2info.asm
index 092d8706..c11d8fb7 100644
--- a/Source/Apps/Test/ps2info/ps2info.asm
+++ b/Source/Apps/Test/ps2info/ps2info.asm
@@ -9,6 +9,7 @@
 ; WBW 2022-03-28: Add menu driven port selection
 ;                 Add support for RHYOPHYRE
 ; WBW 2022-04-01: Add menu for test functions
+; WBW 2022-04-02: Fix prtchr register saving/recovery
 ;
 ;=======================================================================
 ;
@@ -1116,7 +1117,8 @@ err_ret:
 ; Print character in A without destroying any registers
 ;
 prtchr:
-	push	bc		; save registers
+	push	af		; save registers
+	push	bc
 	push	de
 	push	hl
 	ld	e,a		; character to print in E
@@ -1125,6 +1127,7 @@ prtchr:
 	pop	hl		; restore registers
 	pop	de
 	pop	bc
+	pop	af
 	ret
 ;
 prtdot:
@@ -1341,7 +1344,7 @@ delay1:
 ; Constants
 ;=======================================================================
 ;
-str_banner		.db	"PS/2 Keyboard/Mouse Information v0.6, 1-Apr-2022",0
+str_banner		.db	"PS/2 Keyboard/Mouse Information v0.6a, 2-Apr-2022",0
 str_hwmenu		.db	"PS/2 Controller Port Options:\r\n\r\n"
 			.db	"  1 - MBC\r\n"
 			.db	"  2 - RHYOPHYRE\r\n"
diff --git a/Source/HBIOS/Config/RPH_std.asm b/Source/HBIOS/Config/RPH_std.asm
index 8a3d4b22..ce191500 100644
--- a/Source/HBIOS/Config/RPH_std.asm
+++ b/Source/HBIOS/Config/RPH_std.asm
@@ -38,4 +38,4 @@ RAMSIZE		.SET	512		; SIZE OF RAM IN KB (MUST MATCH YOUR HARDWARE!!!)
 ;
 CRTACT		.SET	FALSE		; ACTIVATE CRT (VDU,CVDU,PROPIO,ETC) AT STARTUP
 ;
-PPIDEENABLE	.SET	FALSE		; PPIDE: ENABLE PARALLEL PORT IDE DISK DRIVER (PPIDE.ASM)
+PPIDEENABLE	.SET	TRUE		; PPIDE: ENABLE PARALLEL PORT IDE DISK DRIVER (PPIDE.ASM)
diff --git a/Source/HBIOS/cfg_dyno.asm b/Source/HBIOS/cfg_dyno.asm
index d9421fea..bf106d46 100644
--- a/Source/HBIOS/cfg_dyno.asm
+++ b/Source/HBIOS/cfg_dyno.asm
@@ -116,9 +116,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_ezz80.asm b/Source/HBIOS/cfg_ezz80.asm
index d5339255..8547b7aa 100644
--- a/Source/HBIOS/cfg_ezz80.asm
+++ b/Source/HBIOS/cfg_ezz80.asm
@@ -153,9 +153,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_master.asm b/Source/HBIOS/cfg_master.asm
index abc83e15..fcf194c1 100644
--- a/Source/HBIOS/cfg_master.asm
+++ b/Source/HBIOS/cfg_master.asm
@@ -211,9 +211,11 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_ECB	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_CGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
+GDCMODE		.EQU	GDCMODE_RPH	; GDC: GDC MODE: GDCMODE_[NONE|ECB|RPH]
+GDCMON		.EQU	GDCMON_EGA      ; GDC: GDC MONITOR SETUP: GDCMON_[NONE|CGA|EGA]
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_mbc.asm b/Source/HBIOS/cfg_mbc.asm
index 7a7f80f8..b6e0becf 100644
--- a/Source/HBIOS/cfg_mbc.asm
+++ b/Source/HBIOS/cfg_mbc.asm
@@ -141,9 +141,9 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	TRUE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_MBC	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_CGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
-TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_SCG	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
+TMSENABLE	.EQU	TRUE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
+TMSMODE		.EQU	TMSMODE_MBC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_mk4.asm b/Source/HBIOS/cfg_mk4.asm
index 73aaa8e2..2c8b2854 100644
--- a/Source/HBIOS/cfg_mk4.asm
+++ b/Source/HBIOS/cfg_mk4.asm
@@ -141,9 +141,9 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_ECB	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_EGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_SCG	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_SCG	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_n8.asm b/Source/HBIOS/cfg_n8.asm
index acc3aaa5..a49c971e 100644
--- a/Source/HBIOS/cfg_n8.asm
+++ b/Source/HBIOS/cfg_n8.asm
@@ -143,9 +143,9 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_ECB	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_EGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	TRUE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_N8	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_N8	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_rcz180.asm b/Source/HBIOS/cfg_rcz180.asm
index 4c0ee626..7d0eda26 100644
--- a/Source/HBIOS/cfg_rcz180.asm
+++ b/Source/HBIOS/cfg_rcz180.asm
@@ -160,9 +160,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_rcz280.asm b/Source/HBIOS/cfg_rcz280.asm
index cfe8bbff..c0ff8a93 100644
--- a/Source/HBIOS/cfg_rcz280.asm
+++ b/Source/HBIOS/cfg_rcz280.asm
@@ -175,9 +175,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_rcz80.asm b/Source/HBIOS/cfg_rcz80.asm
index 3628aae0..f135ac21 100644
--- a/Source/HBIOS/cfg_rcz80.asm
+++ b/Source/HBIOS/cfg_rcz80.asm
@@ -164,9 +164,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_rph.asm b/Source/HBIOS/cfg_rph.asm
index a6d8fe5d..c94677bc 100644
--- a/Source/HBIOS/cfg_rph.asm
+++ b/Source/HBIOS/cfg_rph.asm
@@ -141,9 +141,11 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_ECB	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_EGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	TRUE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
+GDCMODE		.EQU	GDCMODE_RPH	; GDC: GDC MODE: GDCMODE_[NONE|ECB|RPH]
+GDCMON		.EQU	GDCMON_EGA      ; GDC: GDC MONITOR SETUP: GDCMON_[NONE|CGA|EGA]
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_N8	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_N8	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_sbc.asm b/Source/HBIOS/cfg_sbc.asm
index 1df79bc0..0e59c183 100644
--- a/Source/HBIOS/cfg_sbc.asm
+++ b/Source/HBIOS/cfg_sbc.asm
@@ -141,9 +141,9 @@ VDUSIZ		.EQU	V80X25		; VDU: DISPLAY FORMAT [V80X24|V80X25|V80X30]
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
 CVDUMODE	.EQU	CVDUMODE_ECB	; CVDU: CVDU MODE: CVDUMODE_[NONE|ECB|MBC]
 CVDUMON		.EQU	CVDUMON_EGA	; CVDU: CVDU MONITOR SETUP: CVDUMON_[NONE|CGA|EGA]
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_SCG	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_SCG	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 VGASIZ		.EQU	V80X25		; VGA: DISPLAY FORMAT [V80X25|V80X30|V80X43]
diff --git a/Source/HBIOS/cfg_scz180.asm b/Source/HBIOS/cfg_scz180.asm
index a801d14d..3a7e4149 100644
--- a/Source/HBIOS/cfg_scz180.asm
+++ b/Source/HBIOS/cfg_scz180.asm
@@ -155,9 +155,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_RC	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_zeta.asm b/Source/HBIOS/cfg_zeta.asm
index 1e6a3f80..3b16bca2 100644
--- a/Source/HBIOS/cfg_zeta.asm
+++ b/Source/HBIOS/cfg_zeta.asm
@@ -114,9 +114,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/cfg_zeta2.asm b/Source/HBIOS/cfg_zeta2.asm
index a0cc2896..27f5bbb3 100644
--- a/Source/HBIOS/cfg_zeta2.asm
+++ b/Source/HBIOS/cfg_zeta2.asm
@@ -125,9 +125,9 @@ XIOCFG		.EQU	DEFSERCFG	; XIO: SERIAL LINE CONFIG
 ;
 VDUENABLE	.EQU	FALSE		; VDU: ENABLE VDU VIDEO/KBD DRIVER (VDU.ASM)
 CVDUENABLE	.EQU	FALSE		; CVDU: ENABLE CVDU VIDEO/KBD DRIVER (CVDU.ASM)
-NECENABLE	.EQU	FALSE		; NEC: ENABLE NEC UPD7220 VIDEO/KBD DRIVER (NEC.ASM)
+GDCENABLE	.EQU	FALSE		; GDC: ENABLE 7220 GDC VIDEO/KBD DRIVER (GDC.ASM)
 TMSENABLE	.EQU	FALSE		; TMS: ENABLE TMS9918 VIDEO/KBD DRIVER (TMS.ASM)
-TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|RC|RCV9958|RCKBD]
+TMSMODE		.EQU	TMSMODE_NONE	; TMS: DRIVER MODE: TMSMODE_[SCG|N8|MBC|RC|RCV9958|RCKBD]
 TMSTIMENABLE	.EQU	FALSE		; TMS: ENABLE TIMER INTERRUPTS (REQUIRES IM1)
 VGAENABLE	.EQU	FALSE		; VGA: ENABLE VGA VIDEO/KBD DRIVER (VGA.ASM)
 ;
diff --git a/Source/HBIOS/gdc.asm b/Source/HBIOS/gdc.asm
new file mode 100644
index 00000000..1bd57ce4
--- /dev/null
+++ b/Source/HBIOS/gdc.asm
@@ -0,0 +1,331 @@
+;======================================================================
+;	UPD7220 GRAPHICS DEVICE CONTROLLER
+;======================================================================
+;
+;======================================================================
+; GDC DRIVER - CONSTANTS
+;======================================================================
+;
+#IF (GDCMODE == GDCMODE_ECB)
+GDC_BASE	.EQU	$??		; GDC BASE I/O PORT
+GDC_DAC_BASE	.EQU	$??		; RAMDAC BASE I/O PORT
+#ENDIF
+;
+#IF (GDCMODE == GDCMODE_RPH)
+GDC_KBDDATA	.EQU	$8C		; KBD CTLR DATA PORT
+GDC_KBDST	.EQU	$8D		; KBD CTLR STATUS/CMD PORT
+GDC_BASE	.EQU	$90		; GDC BASE I/O PORT
+GDC_DAC_BASE	.EQU	$98		; RAMDAC BASE I/O PORT
+#ENDIF
+;
+GDC_STAT	.EQU	GDC_BASE + 0		; STATUS PORT
+GDC_CMD		.EQU	GDC_BASE + 1		; COMMAND PORT
+GDC_PARAM	.EQU	GDC_BASE + 0		; PARAM PORT
+GDC_READ	.EQU	GDC_BASE + 1		; READ PORT
+GDC_DAC_WR	.EQU	GDC_DAC_BASE + 0	; RAMDAC ADR WRITE
+GDC_DAC_RD      .EQU	GDC_DAC_BASE + 3	; RAMDAC ADR READ
+GDC_DAC_PALRAM  .EQU	GDC_DAC_BASE + 1	; RAMDAC PALETTE RAM
+GDC_DAC_PIXMSK  .EQU	GDC_DAC_BASE + 2	; RAMDAC PIXEL READ MASK
+GDC_DAC_OVL_WR  .EQU	GDC_DAC_BASE + 4	; RAMDAC OVERLAY WRITE
+GDC_DAC_OVL_RD  .EQU	GDC_DAC_BASE + 7	; RAMDAC OVERLAY READ
+GDC_DAC_OVL_RAM .EQU	GDC_DAC_BASE + 5	; RAMDAC OVERLAY RAM
+;
+GDC_ROWS	.EQU	25
+GDC_COLS	.EQU	80
+;
+; *** TODO: CGA AND EGA ARE PLACEHOLDERS.  THESE EQUATES SHOULD
+; BE USED TO ALLOW FOR MULTIPLE MONITOR TIMINGS AND/OR FONT
+; DEFINITIONS.
+;
+#IF (GDCMON == GDCMON_CGA)
+  #DEFINE	USEFONTCGA
+  #DEFINE	GDC_FONT FONTCGA
+#ENDIF
+;
+#IF (GDCMON == GDCMON_EGA)
+  #DEFINE	USEFONT8X16
+  #DEFINE	GDC_FONT FONT8X16
+#ENDIF
+;
+TERMENABLE	.SET	TRUE		; INCLUDE TERMINAL PSEUDODEVICE DRIVER
+;
+;======================================================================
+; GDC DRIVER - INITIALIZATION
+;======================================================================
+;
+GDC_INIT:
+	LD	IY,GDC_IDAT		; POINTER TO INSTANCE DATA
+	
+	CALL	NEWLINE
+	PRTS("GDC: MODE=$")
+#IF (GDCMODE == GDCMODE_ECB)
+	PRTS("ECB$")
+#ENDIF
+#IF (GDCMODE == GDCMODE_RPH)
+	PRTS("RPH$")
+#ENDIF
+;
+#IF (GDCMON == GDCMON_CGA)
+	PRTS(" CGA$")
+#ENDIF	
+#IF (GDCMON == GDCMON_EGA)
+	PRTS(" EGA$")
+#ENDIF	
+;
+	PRTS(" IO=0x$")
+	LD	A,GDC_BASE
+	CALL	PRTHEXBYTE
+	CALL	GDC_PROBE		; CHECK FOR HW PRESENCE
+	JR	Z,GDC_INIT1		; CONTINUE IF HW PRESENT
+;
+	; HARDWARE NOT PRESENT
+	PRTS(" NOT PRESENT$")
+	OR	$FF			; SIGNAL FAILURE
+	RET
+;
+GDC_INIT1:
+	CALL 	GDC_CRTINIT		; SETUP THE GDC CHIP REGISTERS
+	CALL	GDC_VDARES		; RESET GDC
+	CALL	KBD_INIT		; INITIALIZE KEYBOARD DRIVER
+
+	; ADD OURSELVES TO VDA DISPATCH TABLE
+	LD	BC,GDC_FNTBL		; BC := FUNCTION TABLE ADDRESS
+	LD	DE,GDC_IDAT		; DE := GDC INSTANCE DATA PTR
+	CALL	VDA_ADDENT		; ADD ENTRY, A := UNIT ASSIGNED
+
+	; INITIALIZE EMULATION
+	LD	C,A			; C := ASSIGNED VIDEO DEVICE NUM
+	LD	DE,GDC_FNTBL		; DE := FUNCTION TABLE ADDRESS
+	LD	HL,GDC_IDAT		; HL := GDC INSTANCE DATA PTR
+	CALL	TERM_ATTACH		; DO IT
+
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+;======================================================================
+; GDC DRIVER - VIDEO DISPLAY ADAPTER (VDA) FUNCTIONS
+;======================================================================
+;
+GDC_FNTBL:
+	.DW	GDC_VDAINI
+	.DW	GDC_VDAQRY
+	.DW	GDC_VDARES
+	.DW	GDC_VDADEV
+	.DW	GDC_VDASCS
+	.DW	GDC_VDASCP
+	.DW	GDC_VDASAT
+	.DW	GDC_VDASCO
+	.DW	GDC_VDAWRC
+	.DW	GDC_VDAFIL
+	.DW	GDC_VDACPY
+	.DW	GDC_VDASCR
+	.DW	KBD_STAT
+	.DW	KBD_FLUSH
+	.DW	KBD_READ
+	.DW	GDC_VDARDC
+#IF (($ - GDC_FNTBL) != (VDA_FNCNT * 2))
+	.ECHO	"*** INVALID GDC FUNCTION TABLE ***\n"
+	!!!!!
+#ENDIF
+;
+GDC_VDAINI:
+	; RESET VDA
+	CALL	GDC_VDARES		; RESET VDA
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+GDC_VDAQRY:	; VIDEO INFORMATION QUERY
+	LD	C,$00		; MODE ZERO IS ALL WE KNOW
+	LD	D,GDC_ROWS	; ROWS
+	LD	E,GDC_COLS	; COLS
+	LD	HL,0		; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
+	XOR	A		; SIGNAL SUCCESS
+	RET
+;
+GDC_VDARES:	; VIDEO SYSTEM RESET
+	; *** TODO: RESET VIDEO SYSTEM HERE, CLEAR SCREEN,
+	; CURSOR TO TOP LEFT, CLEAR ATTRIBUTES
+	XOR	A
+	RET
+;
+GDC_VDADEV:	; VIDEO DEVICE INFORMATION
+	LD	D,VDADEV_GDC	; D := DEVICE TYPE
+	LD	E,0		; E := PHYSICAL UNIT IS ALWAYS ZERO
+	LD	H,0		; H := 0, DRIVER HAS NO MODES
+	LD	L,GDC_BASE	; L := BASE I/O ADDRESS
+	XOR	A		; SIGNAL SUCCESS
+	RET
+;
+GDC_VDASCS:	; SET CURSOR STYLE
+	CALL	SYSCHK		; NOT IMPLEMENTED (YET)
+	LD	A,ERR_NOTIMPL
+	OR	A
+	RET
+
+GDC_VDASCP:	; SET CURSOR POSITION
+	CALL	GDC_XY		; SET CURSOR POSITION
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+GDC_VDASAT:	; SET ATTRIBUTES
+	LD	A,E		; GET THE INCOMING ATTRIBUTE
+	LD	(GDC_ATTR),A	; AND SAVE FOR LATER
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+GDC_VDASCO:	; SET COLOR
+	LD	A,E		; GET THE INCOMING COLOR
+	LD	(GDC_COLOR),A	; AND SAVE FOR LATER
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+GDC_VDAWRC:	; WRITE CHARACTER
+	LD	A,E		; CHARACTER TO WRITE GOES IN A
+	CALL	GDC_PUTCHAR	; PUT IT ON THE SCREEN
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+GDC_VDAFIL:	; FILL WITH CHARACTER
+	LD	A,E		; FILL CHARACTER GOES IN A
+	EX	DE,HL		; FILL LENGTH GOES IN DE
+	CALL	GDC_FILL	; DO THE FILL
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+GDC_VDACPY:	; COPY CHARACTERS/ATTRIBUTES
+	; LENGTH IN HL, SOURCE ROW/COL IN DE, DEST IS GDC_POS
+	; BLKCPY USES: HL=SOURCE, DE=DEST, BC=COUNT
+	PUSH	HL		; SAVE LENGTH
+	CALL	GDC_XY2IDX	; ROW/COL IN DE -> SOURCE ADR IN HL
+	POP	BC		; RECOVER LENGTH IN BC
+	LD	DE,(GDC_POS)	; PUT DEST IN DE
+	JP	GDC_BLKCPY	; DO A BLOCK COPY
+
+GDC_VDASCR:	; SCROLL ENTIRE SCREEN
+	LD	A,E		; LOAD E INTO A
+	OR	A		; SET FLAGS
+	RET	Z		; IF ZERO, WE ARE DONE
+	PUSH	DE		; SAVE E
+	JP	M,GDC_VDASCR1	; E IS NEGATIVE, REVERSE SCROLL
+	CALL	GDC_SCROLL	; SCROLL FORWARD ONE LINE
+	POP	DE		; RECOVER E
+	DEC	E		; DECREMENT IT
+	JR	GDC_VDASCR	; LOOP
+GDC_VDASCR1:
+	CALL	GDC_RSCROLL	; SCROLL REVERSE ONE LINE
+	POP	DE		; RECOVER E
+	INC	E		; INCREMENT IT
+	JR	GDC_VDASCR	; LOOP
+;
+GDC_VDARDC:	; READ CHAR/ATTR VALUE FROM VIDEO BUFFER
+	OR	$FF		; UNSUPPORTED FUNCTION
+	RET
+;
+;======================================================================
+; GDC DRIVER - PRIVATE DRIVER FUNCTIONS
+;======================================================================
+;
+;----------------------------------------------------------------------
+; PROBE FOR GDC HARDWARE
+;----------------------------------------------------------------------
+;
+; ON RETURN, ZF SET INDICATES HARDWARE FOUND
+;
+; *** TODO: IMPLEMENT THIS
+;
+GDC_PROBE:
+	XOR	A			; SIGNAL SUCCESS
+	RET				; RETURN WITH ZF SET BASED ON CP
+;
+;----------------------------------------------------------------------
+; DISPLAY CONTROLLER CHIP INITIALIZATION
+;----------------------------------------------------------------------
+;
+; *** TODO: IMPLEMENT THIS
+;
+GDC_CRTINIT:
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+;----------------------------------------------------------------------
+; SET CURSOR POSITION TO ROW IN D AND COLUMN IN E
+;----------------------------------------------------------------------
+;
+GDC_XY:
+	CALL	GDC_XY2IDX		; CONVERT ROW/COL TO BUF IDX
+	LD	(GDC_POS),HL		; SAVE THE RESULT (DISPLAY POSITION)
+	; *** TODO: MOVE THE CURSOR
+	RET
+;
+;----------------------------------------------------------------------
+; CONVERT XY COORDINATES IN DE INTO LINEAR INDEX IN HL
+; D=ROW, E=COL
+;----------------------------------------------------------------------
+;
+GDC_XY2IDX:
+	LD	A,E			; SAVE COLUMN NUMBER IN A
+	LD	H,D			; SET H TO ROW NUMBER
+	LD	E,GDC_COLS		; SET E TO ROW LENGTH
+	CALL	MULT8			; MULTIPLY TO GET ROW OFFSET
+	LD	E,A			; GET COLUMN BACK
+	ADD	HL,DE			; ADD IT IN
+	RET				; RETURN
+;
+;----------------------------------------------------------------------
+; WRITE VALUE IN A TO CURRENT VDU BUFFER POSITION, ADVANCE CURSOR
+;----------------------------------------------------------------------
+;
+GDC_PUTCHAR:
+	; *** TODO: IMPLEMENT THIS
+	RET
+;
+;----------------------------------------------------------------------
+; FILL AREA IN BUFFER WITH SPECIFIED CHARACTER AND CURRENT COLOR/ATTRIBUTE
+; STARTING AT THE CURRENT FRAME BUFFER POSITION
+;   A: FILL CHARACTER
+;   DE: NUMBER OF CHARACTERS TO FILL
+;----------------------------------------------------------------------
+;
+GDC_FILL:
+	; *** TODO: IMPLEMENT THIS
+	RET
+;
+;----------------------------------------------------------------------
+; SCROLL ENTIRE SCREEN FORWARD BY ONE LINE (CURSOR POSITION UNCHANGED)
+;----------------------------------------------------------------------
+;
+GDC_SCROLL:
+	; *** TODO: IMPLEMENT THIS
+	RET
+;
+;----------------------------------------------------------------------
+; REVERSE SCROLL ENTIRE SCREEN BY ONE LINE (CURSOR POSITION UNCHANGED)
+;----------------------------------------------------------------------
+;
+GDC_RSCROLL:
+	; *** TODO: IMPLEMENT THIS
+	RET
+;
+;----------------------------------------------------------------------
+; BLOCK COPY BC BYTES FROM HL TO DE
+;----------------------------------------------------------------------
+;
+GDC_BLKCPY:
+	; *** TODO: IMPLEMENT THIS
+	RET
+;
+;==================================================================================================
+;   GDC DRIVER - DATA
+;==================================================================================================
+;
+GDC_ATTR	.DB	0	; CURRENT ATTRIBUTES
+GDC_COLOR	.DB	0	; CURRENT COLOR
+GDC_POS		.DW 	0	; CURRENT DISPLAY POSITION
+;
+;==================================================================================================
+;   GDC DRIVER - INSTANCE DATA
+;==================================================================================================
+;
+GDC_IDAT:
+	.DB	GDC_KBDST
+	.DB	GDC_KBDDATA
diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index b2e8ed35..8fcc5a53 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -2987,8 +2987,8 @@ HB_INITTBL:
 #IF (VGAENABLE)
 	.DW	VGA_INIT
 #ENDIF
-#IF (NECENABLE)
-	.DW	NEC_INIT
+#IF (GDCENABLE)
+	.DW	GDC_INIT
 #ENDIF
 #IF (TMSENABLE)
 	.DW	TMS_INIT
@@ -5839,12 +5839,12 @@ SIZ_TMS		.EQU	$ - ORG_TMS
 		.ECHO	" bytes.\n"
 #ENDIF
 ;
-#IF (NECENABLE)
-ORG_NEC	.EQU	$
-  ;#INCLUDE "nec.asm"
-SIZ_NEC	.EQU	$ - ORG_NEC
-		.ECHO	"NEC occupies "
-		.ECHO	SIZ_NEC
+#IF (GDCENABLE)
+ORG_GDC	.EQU	$
+  #INCLUDE "gdc.asm"
+SIZ_GDC	.EQU	$ - ORG_GDC
+		.ECHO	"GDC occupies "
+		.ECHO	SIZ_GDC
 		.ECHO	" bytes.\n"
 #ENDIF
 ;
@@ -5908,7 +5908,7 @@ SIZ_FONTS	.EQU	$ - ORG_FONTS
 		.ECHO	SIZ_FONTS
 		.ECHO	" bytes.\n"
 ;
-#IF (CVDUENABLE | VGAENABLE) | (TMSENABLE & (TMSMODE == TMSMODE_RCKBD))
+#IF (CVDUENABLE | VGAENABLE) | GDCENABLE | (TMSENABLE & (TMSMODE == TMSMODE_RCKBD))
 ORG_KBD		.EQU	$
   #INCLUDE "kbd.asm"
 SIZ_KBD		.EQU	$ - ORG_KBD
@@ -6133,7 +6133,7 @@ SIZ_AY38910	.EQU	$ - ORG_AY38910
 ;
 ; INCLUDE LZSA2 decompression engine if required.
 ;
-#IF ((VGAENABLE | CVDUENABLE | TMSENABLE) & USELZSA2)
+#IF ((VGAENABLE | CVDUENABLE | TMSENABLE | GDCENABLE) & USELZSA2)
 #INCLUDE "unlzsa2s.asm"
 #ENDIF
 ;
@@ -6927,11 +6927,11 @@ PIO_MODE_STR:	.TEXT	"Output$"
 ; VIDEO DEVICE STRINGS
 ;
 PS_VDSTRREF:
-	.DW	PS_VDVDU, PS_VDCVDU, PS_VDNEC, PS_VDTMS, PS_VDVGA
+	.DW	PS_VDVDU, PS_VDCVDU, PS_VDGDC, PS_VDTMS, PS_VDVGA
 ;
 PS_VDVDU	.TEXT	"VDU$"
 PS_VDCVDU	.TEXT	"CVDU$"
-PS_VDNEC	.TEXT	"NEC$"
+PS_VDGDC	.TEXT	"GDC$"
 PS_VDTMS	.TEXT	"TMS$"
 PS_VDVGA	.TEXT	"VGA$"
 ;
diff --git a/Source/HBIOS/hbios.inc b/Source/HBIOS/hbios.inc
index bce5c5ff..93a9ef4a 100644
--- a/Source/HBIOS/hbios.inc
+++ b/Source/HBIOS/hbios.inc
@@ -218,7 +218,7 @@ RTCDEV_RP5	.EQU	$50		; RP5C01
 ;
 VDADEV_VDU	.EQU	$00		; ECB VDU - MOTOROLA 6545
 VDADEV_CVDU	.EQU	$10		; ECB COLOR VDU - MOS 8563
-VDADEV_NEC	.EQU	$20		; ECB UPD7220 - NEC UPD7220
+VDADEV_GDC	.EQU	$20		; GRAPHICS DISPLAY CTLR - UPD7220
 VDADEV_TMS	.EQU	$30		; N8 ONBOARD VDA SUBSYSTEM - TMS 9918
 VDADEV_VGA	.EQU	$40		; ECB VGA3 - HITACHI HD6445
 ;VDADEV_V9958	.EQU	$50		; V9958 VDU
diff --git a/Source/HBIOS/std.asm b/Source/HBIOS/std.asm
index 3b51c666..e32a6fac 100644
--- a/Source/HBIOS/std.asm
+++ b/Source/HBIOS/std.asm
@@ -199,7 +199,7 @@ AYMODE_LINC	.EQU	6		; LINC Z50 AY SOUND CARD
 AYMODE_MBC	.EQU	7		; MBC SOUND BOARD
 ;
 ; SN SOUND CHIP MODE SELECTIONS
-; 
+;
 SNMODE_NONE	.EQU	0
 SNMODE_RCZ80	.EQU	1		; RC2014 SOUND MODULE
 SNMODE_VGM	.EQU	2		; VGM ECB BOARD
@@ -212,6 +212,7 @@ TMSMODE_N8	.EQU	2		; N8 BUILT-IN VIDEO
 TMSMODE_RC	.EQU	3		; RC2014 TMS9918 VIDEO BOARD
 TMSMODE_RCV9958	.EQU	4		; RC2014 V9958 VIDEO BOARD
 TMSMODE_RCKBD	.EQU	5		; RC2014 TMS9918 + PS2 KEYBOARD
+TMSMODE_MBC	.EQU	6		; MBC V9938/58 VIDEO BOARD
 ;
 ; CVDU VIDEO MODE SELECTIONS
 ;
@@ -225,6 +226,18 @@ CVDUMON_NONE	.EQU	0
 CVDUMON_CGA	.EQU	1		; CGA MONITOR TIMING (16.000 MHZ OSC)
 CVDUMON_EGA	.EQU	2		; EGA MONITOR TIMING (16.257 MHZ OSC)
 ;
+; GDC VIDEO MODE SELECTIONS
+;
+GDCMODE_NONE	.EQU	0
+GDCMODE_ECB	.EQU	1		; ECB GDC
+GDCMODE_RPH	.EQU	2		; RPH GDC
+;
+; GDC MONITOR SELECTIONS
+;
+GDCMON_NONE	.EQU	0
+GDCMON_CGA	.EQU	1		; CGA MONITOR TIMING (16.000 MHZ OSC)
+GDCMON_EGA	.EQU	2		; EGA MONITOR TIMING (16.257 MHZ OSC)
+;
 ; DMA MODE SELECTIONS
 ;
 DMAMODE_NONE	.EQU	0
@@ -555,22 +568,22 @@ BID_ROMDN	.SET	$FF		; ROM DRIVE DISABLED
 	.ECHO "BID_BIOS: " \ .ECHO BID_BIOS \ .ECHO "\n"
 	.ECHO "BID_USR: " \ .ECHO BID_USR \ .ECHO "\n"
 	.ECHO "BID_COM: " \ .ECHO BID_COM \ .ECHO "\n"
-	
+
 	.ECHO "BID_BOOT: " \ .ECHO BID_BOOT \ .ECHO "\n"
 	.ECHO "BID_IMG0: " \ .ECHO BID_IMG0 \ .ECHO "\n"
 	.ECHO "BID_IMG1: " \ .ECHO BID_IMG1 \ .ECHO "\n"
 	.ECHO "BID_IMG2: " \ .ECHO BID_IMG2 \ .ECHO "\n"
-	
+
 	.ECHO "BID_ROMD0: " \ .ECHO BID_ROMD0 \ .ECHO "\n"
 	.ECHO "BID_ROMDN: " \ .ECHO BID_ROMDN \ .ECHO "\n"
 	.ECHO "BID_RAMD0: " \ .ECHO BID_RAMD0 \ .ECHO "\n"
 	.ECHO "BID_RAMDN: " \ .ECHO BID_RAMDN \ .ECHO "\n"
-	
+
 	.ECHO "BID_ROM0: " \ .ECHO BID_ROM0 \ .ECHO "\n"
 	.ECHO "BID_ROMN: " \ .ECHO BID_ROMN \ .ECHO "\n"
 	.ECHO "BID_RAM0: " \ .ECHO BID_RAM0 \ .ECHO "\n"
 	.ECHO "BID_RAMN: " \ .ECHO BID_RAMN \ .ECHO "\n"
-#ENDIF		
+#ENDIF
 ;
 ; MEMORY LAYOUT
 ;
@@ -708,7 +721,7 @@ INT_CTC0D	.EQU	15	; ZILOG CTC 0, CHANNEL D
 ;INT_PIO0B	.EQU	10	; ZILOG PIO 0, CHANNEL B
 ;INT_PIO1A	.EQU	11	; ZILOG PIO 1, CHANNEL A
 ;INT_PIO1B	.EQU	12	; ZILOG PIO 1, CHANNEL B
-    
+
     #ELSE
 
 INT_CTC0A	.EQU	0	; ZILOG CTC 0, CHANNEL A
diff --git a/Source/HBIOS/tms.asm b/Source/HBIOS/tms.asm
index 2a585634..d1978a41 100644
--- a/Source/HBIOS/tms.asm
+++ b/Source/HBIOS/tms.asm
@@ -63,9 +63,22 @@ TMS_PPIX	.EQU	0		; PPI CONTROL PORT
 
 #ENDIF
 ;
+#IF (TMSMODE == TMSMODE_MBC)
+
+TMS_DATREG	.EQU	$98		; READ/WRITE DATA
+TMS_CMDREG	.EQU	$99		; READ STATUS / WRITE REG SEL
+TMS_ACR		.EQU	$9C		; AUX CONTROL REGISTER
+TMS_PPIA	.EQU	0		; PPI PORT A
+TMS_PPIB	.EQU	0		; PPI PORT B
+TMS_PPIC	.EQU	0		; PPI PORT C
+TMS_PPIX	.EQU	0		; PPI CONTROL PORT
+TMS_KBDDATA	.EQU	$E2		; KBD CTLR DATA PORT
+TMS_KBDST	.EQU	$E3		; KBD CTLR STATUS/CMD PORT
+#ENDIF
+
 TMS_ROWS	.EQU	24
 
-#IF (TMSMODE == TMSMODE_RCV9958)
+#IF ((TMSMODE == TMSMODE_RCV9958) | (TMSMODE == TMSMODE_MBC))
 TMS_FNTVADDR	.EQU	$1000		; VRAM ADDRESS OF FONT DATA
 TMS_COLS	.EQU	80
 #ELSE
@@ -86,7 +99,7 @@ TERMENABLE	.SET	TRUE		; INCLUDE TERMINAL PSEUDODEVICE DRIVER
 #DEFINE		TMS_IODELAY	EX (SP),HL \ EX (SP),HL	; 38 W/S
 #ELSE
 ; BELOW WAS TUNED FOR SBC AT 8MHZ
-#IF (TMSMODE == TMSMODE_RCV9958)
+#IF ((TMSMODE == TMSMODE_RCV9958) | (TMSMODE == TMSMODE_MBC))
 #DEFINE		TMS_IODELAY	NOP \ NOP \ NOP \ NOP \ NOP \ NOP \ NOP ; V9958 NEEDS AT WORST CASE, APPROX 4us (28T) DELAY BETWEEN I/O (WHEN IN TEXT MODE)
 #ELSE
 #DEFINE		TMS_IODELAY	NOP \ NOP ; 8 W/S
@@ -110,18 +123,28 @@ TMS_INIT:
 	CALL	TMS_Z180IO
 #ENDIF
 ;
-#IF (TMSMODE == TMSMODE_SCG)
+#IF ((TMSMODE == TMSMODE_SCG) | (TMSMODE == TMSMODE_MBC))
 	LD	A,$FF
 	OUT	(TMS_ACR),A		; INIT AUX CONTROL REG
 #ENDIF
-;
-	LD	IY,TMS_IDAT		; POINTER TO INSTANCE DATA
 ;
 	CALL	NEWLINE			; FORMATTING
 	PRTS("TMS: MODE=$")
+
+#IF ((TMSMODE == TMSMODE_MBC))
+	LD	A,$FE
+	OUT	(TMS_ACR),A		; INIT AUX CONTROL REG
+#ENDIF
+
+
+	LD	IY,TMS_IDAT		; POINTER TO INSTANCE DATA
+;
 #IF (TMSMODE == TMSMODE_SCG)
 	PRTS("SCG$")
 #ENDIF
+#IF (TMSMODE == TMSMODE_MBC)
+	PRTS("MBC$")
+#ENDIF
 #IF (TMSMODE == TMSMODE_N8)
 	PRTS("N8$")
 #ENDIF
@@ -153,7 +176,7 @@ TMS_INIT1:
 #IF (TMSMODE == TMSMODE_N8)
 	CALL	PPK_INIT		; INITIALIZE PPI KEYBOARD DRIVER
 #ENDIF
-#IF (TMSMODE == TMSMODE_RCKBD)
+#IF ((TMSMODE == TMSMODE_RCKBD) | (TMSMODE == TMSMODE_MBC))
 	CALL	KBD_INIT		; INITIALIZE 8242 KEYBOARD DRIVER
 #ENDIF
 #IF MKYENABLE
@@ -208,7 +231,7 @@ TMS_FNTBL:
 	.DW	PPK_FLUSH
 	.DW	PPK_READ
 #ELSE
-  #IF  (TMSMODE == TMSMODE_RCKBD)
+  #IF  ((TMSMODE == TMSMODE_RCKBD) | (TMSMODE == TMSMODE_MBC))
   	.DW	KBD_STAT
   	.DW	KBD_FLUSH
   	.DW	KBD_READ
@@ -217,7 +240,7 @@ TMS_FNTBL:
   	.DW	MKY_STAT
   	.DW	MKY_FLUSH
   	.DW	MKY_READ
-  
+
     #ELSE
   	.DW	TMS_STAT
   	.DW	TMS_FLUSH
@@ -412,7 +435,7 @@ TMS_SET:
 ;----------------------------------------------------------------------
 ;
 TMS_WR:
-#IF (TMSMODE == TMSMODE_RCV9958)
+#IF ((TMSMODE == TMSMODE_RCV9958)  | (TMSMODE == TMSMODE_MBC))
         ; CLEAR R#14 FOR V9958
         XOR     A
         OUT     (TMS_CMDREG), A
@@ -903,7 +926,7 @@ TMS_IDAT:
 	.DB	TMS_PPIC        ; PPI PORT C
 	.DB	TMS_PPIX        ; PPI CONTROL PORT
 #ENDIF
-#IF (TMSMODE == TMSMODE_RCKBD)
+#IF ((TMSMODE == TMSMODE_RCKBD) | (TMSMODE == TMSMODE_MBC))
 	.DB	TMS_KBDST	; 8242 CMD/STATUS PORT
 	.DB	TMS_KBDDATA	; 8242 DATA PORT
 #ENDIF
@@ -954,7 +977,7 @@ TMS_PORTS:
 ; 5S		Fifth sprite (not displayed) detected. Value in FS* is valid.
 ; INT		Set at each screen update, used for interrupts.
 ;
-#IF (TMSMODE == TMSMODE_RCV9958)
+#IF ((TMSMODE == TMSMODE_RCV9958)  | (TMSMODE == TMSMODE_MBC))
 TMS_INITVDU:
 	.DB	$04		; REG 0 - NO EXTERNAL VID, SET M4 = 1
 TMS_INITVDU_REG_1:
diff --git a/Source/ver.inc b/Source/ver.inc
index a7451543..14eda264 100644
--- a/Source/ver.inc
+++ b/Source/ver.inc
@@ -2,4 +2,4 @@
 #DEFINE	RMN	1
 #DEFINE	RUP	1
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.1.1-pre.168"
+#DEFINE BIOSVER	"3.1.1-pre.170"
diff --git a/Source/ver.lib b/Source/ver.lib
index dc0185e8..2d68ff32 100644
--- a/Source/ver.lib
+++ b/Source/ver.lib
@@ -3,5 +3,5 @@ rmn	equ	1
 rup	equ	1
 rtp	equ	0
 biosver	macro
-	db	"3.1.1-pre.168"
+	db	"3.1.1-pre.170"
 	endm