diff --git a/src/zvm_m65/z80_instr_general.s b/src/zvm_m65/z80_instr_general.s
index dafaa89d..dc88a098 100644
--- a/src/zvm_m65/z80_instr_general.s
+++ b/src/zvm_m65/z80_instr_general.s
@@ -4,12 +4,63 @@
 ;
 
 
+Z80_instr_2F:      ; CPL
+
+	lda REG_A
+	eor #$FF
+	sta REG_A
+
+	lda REG_F
+	ora #(Z80_HF + Z80_NF)
+	sta REG_F
+	jmp ZVM_next
+
+; XXX put NEG here
+
+Z80_instr_3F:      ; CCF
+
+	+Z80_PUT_0_NF
+	bbs0 REG_F,@1
+@0:
+	+Z80_PUT_0_HF
+	+Z80_PUT_1_CF
+	jmp ZVM_next
+@1:
+	+Z80_PUT_1_HF
+	+Z80_PUT_0_CF
+	jmp ZVM_next
+
+Z80_instr_37:      ; SCF
+
+	+Z80_PUT_0_HF
+	+Z80_PUT_0_NF
+	+Z80_PUT_1_CF
+	jmp ZVM_next
+
+Z80_instr_76:      ; HALT
+
+	; Used to call BIOS routines
+
+	ldx #$01 ; default BIOS function, warm start
+
+	lda REG_PC
+	sec
+	sbc #$64
+	cmp #33
+	bcs @1
+	tax
+@1:
+	txa
+	asl
+	tax
+	jmp (zvm_BIOS_vectable,x)
+
 Z80_instr_F3:      ; DI
 
 	lda #$00
-	+skip_2_bytes_trash_nvz
-
-	; FALLTROUGH
+	sta REG_IFF1
+	sta REG_IFF2
+	jmp ZVM_next
 
 Z80_instr_FB:      ; EI
 
diff --git a/src/zvm_m65/zvm_bios.s b/src/zvm_m65/zvm_bios.s
index 5120a799..b722b289 100644
--- a/src/zvm_m65/zvm_bios.s
+++ b/src/zvm_m65/zvm_bios.s
@@ -3,4 +3,177 @@
 ; Z80 Virtual Machine BIOS for CP/M
 ;
 
-; XXX implement
+
+; Virtual BIOS memory map
+
+; $FE00 - $FE63 - jumptable, 3*33 bytes
+; $FE63 - $FE84 - magic HALT instructions to select BIOS routines
+; $FE85 - $FEFF - unused
+; $FF00 - $FFFF - Disk Drive Tables, dynamically generated, $10 bytes for each one
+
+
+
+
+zvm_BIOS_vectable:
+
+	!word zvm_BIOS_00_BOOT
+	!word zvm_BIOS_01_WBOOT
+	!word zvm_BIOS_02_CONST
+	!word zvm_BIOS_03_CONIN
+	!word zvm_BIOS_04_CONOUT
+	!word zvm_BIOS_05_LIST
+	!word zvm_BIOS_06_AUXOUT
+	!word zvm_BIOS_07_AUXIN
+	!word zvm_BIOS_08_HOME
+	!word zvm_BIOS_09_SELDSK
+	!word zvm_BIOS_10_SETTRK
+	!word zvm_BIOS_11_SETSEC
+	!word zvm_BIOS_12_SETDMA
+	!word zvm_BIOS_13_READ
+	!word zvm_BIOS_14_WRITE
+	!word zvm_BIOS_15_LISTST
+	!word zvm_BIOS_16_SECTRN
+	!word zvm_BIOS_17_CONOST
+	!word zvm_BIOS_18_AUXIST
+	!word zvm_BIOS_19_AUXOST
+	!word zvm_BIOS_20_DEVTBL
+	!word zvm_BIOS_21_DEVINI
+	!word zvm_BIOS_22_DRVTBL
+	!word zvm_BIOS_23_MULTIO
+	!word zvm_BIOS_24_FLUSH
+	!word zvm_BIOS_25_MOVE
+	!word zvm_BIOS_26_TIME
+	!word zvm_BIOS_27_SELMEM
+	!word zvm_BIOS_28_SETBNK
+	!word zvm_BIOS_29_XMOVE
+	!word zvm_BIOS_30_USERF
+	!word zvm_BIOS_31_RESERV1
+	!word zvm_BIOS_32_RESERV2
+
+zvm_BIOS_00_BOOT:            ; Cold start
+
+	; XXX !!!
+
+	; FALLTROUGH
+
+zvm_BIOS_01_WBOOT:           ; Warm start
+zvm_BIOS_31_RESERV1:         ; Reserved   
+zvm_BIOS_32_RESERV2:         ; Reserved
+
+	; XXX !!!
+
+zvm_BIOS_02_CONST:           ; Check if input character available
+
+	; XXX !!!
+
+zvm_BIOS_03_CONIN:           ; Console input
+
+	; XXX !!!
+
+zvm_BIOS_04_CONOUT:          ; Console output
+
+	; XXX
+
+zvm_BIOS_05_LIST:            ; Provide list of character output devices
+
+	; XXX
+
+zvm_BIOS_06_AUXOUT:          ; AUX output
+
+	; XXX
+
+zvm_BIOS_07_AUXIN:           ; AUX input
+
+	; XXX
+
+zvm_BIOS_08_HOME:            ; Go to track 0
+
+	; XXX !!!
+
+zvm_BIOS_09_SELDSK:          ; Select drive
+
+	; XXX !!!
+
+zvm_BIOS_10_SETTRK:          ; Set track number
+
+	; XXX !!!
+
+zvm_BIOS_11_SETSEC:          ; Set sector number
+
+	; XXX !!!
+
+zvm_BIOS_12_SETDMA:          ; Set DMA address
+
+	; XXX !!!
+
+zvm_BIOS_13_READ:            ; Read sector
+
+	; XXX !!!
+
+zvm_BIOS_14_WRITE:           ; Write sector
+
+	; XXX !!!
+
+zvm_BIOS_15_LISTST:          ; List status
+
+	; XXX
+
+zvm_BIOS_16_SECTRN:          ; Convert logical to physical sector
+
+	; XXX !!!
+
+zvm_BIOS_17_CONOST:          ; Console output status
+
+	; XXX
+
+zvm_BIOS_18_AUXIST:          ; AUX input status
+
+	; XXX
+
+zvm_BIOS_19_AUXOST:          ; AUX output status
+
+	; XXX
+
+zvm_BIOS_20_DEVTBL:          ; Character device table address
+
+	; XXX
+
+zvm_BIOS_21_DEVINI:          ; Initialize character device
+
+	; XXX
+
+zvm_BIOS_22_DRVTBL:          ; Disk drive table address
+
+	; XXX
+
+zvm_BIOS_23_MULTIO:          ; Set number of logically consecutive sectors
+
+	; XXX !!!
+
+zvm_BIOS_24_FLUSH:           ; Force buffer flushing for user deblocking
+
+	; XXX !!!
+
+zvm_BIOS_25_MOVE:            ; Memory move
+
+	; XXX
+
+zvm_BIOS_26_TIME:            ; Get or set time
+
+	; XXX !!!
+
+zvm_BIOS_27_SELMEM:          ; Select memory bank
+
+	; XXX
+
+zvm_BIOS_28_SETBNK:          ; Set bank for DMA operation
+
+	; XXX
+
+zvm_BIOS_29_XMOVE:           ; Set bank if buffer is in bank other than 1 or 2
+
+	; XXX
+
+zvm_BIOS_30_USERF:           ; Implementation-specific functionality
+
+	; XXX implement function to save RAM DISK back to SD CARD
diff --git a/src/zvm_m65/zvm_core.s b/src/zvm_m65/zvm_core.s
index c0746e1d..e71b3775 100644
--- a/src/zvm_m65/zvm_core.s
+++ b/src/zvm_m65/zvm_core.s
@@ -41,8 +41,8 @@ ZVM_store_next:
 	asl
 	tax
 	bcs @1
-	jmp (.TAB_LO)            ; execute opcode $00-$7F
-@1: jmp (.TAB_HI)            ; execute opcode $80-$FF
+	jmp (.TAB_LO,x)          ; execute opcode $00-$7F
+@1: jmp (.TAB_HI,x)          ; execute opcode $80-$FF
 
 }
 
@@ -114,14 +114,10 @@ Z80_instr_22:      ; LD (nn),HL
 Z80_instr_27:      ; DAA
 Z80_instr_29:      ; ADD HL,HL
 Z80_instr_2A:      ; LD HL,(nn)
-Z80_instr_2F:      ; CPL
 Z80_instr_31:      ; LD SP,nn
 Z80_instr_32:      ; LD (nn),A
-Z80_instr_37:      ; SCF
 Z80_instr_39:      ; ADD HL,SP
 Z80_instr_3A:      ; LD A,(nn)
-Z80_instr_3F:      ; CCF
-Z80_instr_76:      ; HALT
 Z80_instr_80:      ; ADD A,B
 Z80_instr_81:      ; ADD A,C
 Z80_instr_82:      ; ADD A,D