ZPM3 Drive Map Fix

- Workaround to make ZPM3 consider all drives (A-P) valid so that subsequent drive ASSIGNments work properly.

Source/CBIOS/cbios.asm

@@ -1171,6 +1171,11 @@ DSK_GETINF:
 	RLCA			; ... TO USE AS OFFSET INTO DRVMAP
 	CALL	ADDHLA		; ADD OFFSET
 	LD	D,(HL)		; D := UNIT
+	
+	LD	A,D		; PUT UNIT IN ACCUM
+	INC	A		; $FF -> $00
+	JR	Z,DSK_GETINF1	; HANDLE UNASSIGNED DRIVE LETTER
+	
 	INC	HL		; BUMP TO SLICE
 	LD	E,(HL)		; E := SLICE
 	INC	HL		; POINT TO DPH LSB
@@ -1178,9 +1183,11 @@ DSK_GETINF:
 	INC	HL		; POINT TO DPH MSB
 	LD	H,(HL)		; H := DPH MSB
 	LD	L,A		; L := DPH LSB
-	LD	A,H		; TEST FOR INVALID DPH
-	OR	L		; ... BY CHECKING FOR ZERO VALUE
-	JR	Z,DSK_GETINF1	; HANDLE ZERO DPH, DRIVE IS INVALID
+
+	;LD	A,H		; TEST FOR INVALID DPH
+	;OR	L		; ... BY CHECKING FOR ZERO VALUE
+	;JR	Z,DSK_GETINF1	; HANDLE ZERO DPH, DRIVE IS INVALID
+
 	XOR	A		; SET SUCCESS
 	RET
 ;
@@ -1198,7 +1205,7 @@ DSK_GETINF1:	; ERROR RETURN
 DSK_SELECT:
 	LD	B,E		; SAVE E IN B FOR NOW
 	CALL	DSK_GETINF	; GET D=UNIT, E=SLICE, HL=DPH ADDRESS
-	CALL	NZ,PANIC	; *DEBUG*
+	;CALL	NZ,PANIC	; *DEBUG*
 	RET	NZ		; RETURN IF INVALID DRIVE (A=1, NZ SET, HL=0)
 	PUSH	BC		; WE NEED  B LATER, SAVE ON STACK
 ;

Source/CPM3/boot.z80

@@ -228,25 +228,26 @@ dinit6:
 	pop	de			; restore drive list ptr
 	inc	de			; increment active drive list ptr
 	djnz	dinit6			; loop as needed
+	ret
 
-	; zero out remaining dph table entries
-	ld	a,16			; dph table entries
-	sub	l			; subtract entries used
-	ret	z			; return if all entries used
-	ld	b,a			; save as loop counter
-	ld	a,l			; current dph to accum
-	rlca				; *2 for word entry
-	ld	hl,@dtbl		; start of dtbl
-	call	addhla			; hl now points to entry
-	
-dinit6a:
-	xor	a			; zero accum
-	ld	(hl),a			; zero lsb
-	inc	hl			; next byte
-	ld	(hl),a			; zero msb
-	inc	hl			; next byte
-	djnz	dinit6a
-	ret				; finished
+;	; zero out remaining dph table entries
+;	ld	a,16			; dph table entries
+;	sub	l			; subtract entries used
+;	ret	z			; return if all entries used
+;	ld	b,a			; save as loop counter
+;	ld	a,l			; current dph to accum
+;	rlca				; *2 for word entry
+;	ld	hl,@dtbl		; start of dtbl
+;	call	addhla			; hl now points to entry
+;	
+;dinit6a:
+;	xor	a			; zero accum
+;	ld	(hl),a			; zero lsb
+;	inc	hl			; next byte
+;	ld	(hl),a			; zero msb
+;	inc	hl			; next byte
+;	djnz	dinit6a
+;	ret				; finished
 
 dinit7:	; process a unit (all slices)
 	ld	e,0			; initialize slice index

Source/CPM3/diskio.z80

@@ -60,7 +60,7 @@ bell	equ 7
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph0:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -68,7 +68,7 @@ dph0:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph1:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -76,7 +76,7 @@ dph1:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph2:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -84,7 +84,7 @@ dph2:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph3:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -92,7 +92,7 @@ dph3:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph4:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -100,7 +100,7 @@ dph4:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph5:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -108,7 +108,7 @@ dph5:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph6:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -116,7 +116,7 @@ dph6:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph7:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -124,7 +124,7 @@ dph7:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph8:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -132,7 +132,7 @@ dph8:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph9:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -140,7 +140,7 @@ dph9:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph10:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -148,7 +148,7 @@ dph10:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph11:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -156,7 +156,7 @@ dph11:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph12:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -164,7 +164,7 @@ dph12:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph13:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -172,7 +172,7 @@ dph13:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph14:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -180,7 +180,7 @@ dph14:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	dsk$read
 	dw	dsk$login
 	dw	dsk$init
-	db	0,0		; HBIOS Disk Unit/Slice (filled in at boot)
+	db	0FFh,0FFh	; HBIOS Disk Unit/Slice (filled in at boot)
 dph15:	dph	0,dpb$max	; Real DPB filled in at disk login
 	dw	0, 0		; LBA Offset
 
@@ -409,11 +409,11 @@ dsk$login:
 	dec	hl			; point to disk unit
 	ld	a,(hl)			; get unit
 	ld	(unit),a		; save it
-	call	media			; update DPH for media
-	; Need to do something on error, but bioskrnl provides
-	; no way for us to return an error.
-	;jr	nz,???
-	ret
+	inc	a			; 0FFh -> 000h
+	jp	z,err_ret		; bail out on no disk mapped here
+	
+	;call	media			; update DPH for media
+	;ret
 
 media:
 	; Set retry address