Fix: If the Slice=0 and No CPM partition, boot the disk, ignore all Calculations and checks.

Source/HBIOS/hbios.asm

@@ -4946,14 +4946,14 @@ EXT_SLICE:
 	LD	A,E			; RESULTANT MEDIA ID TO ACCUM
 	LD	(SLICE_MID),A		; INIT VALUE, MAY BE USED LATER
 	OR	A			; SET FLAGS
-	JR	Z, EXT_SLICE1A		; BAIL IF NO MEDIA
+	JR	Z,EXT_SLICE1A		; BAIL IF NO MEDIA
 	CP	MID_HD			; IS IT A HARD DISK
-	JR	Z, EXT_SLICE1B		; IS HD, CONTINUE TO PROCESS HD
+	JR	Z,EXT_SLICE1B		; IS HD, CONTINUE TO PROCESS HD
 ;
 	; NOT A HARD DISK, CHECK SLICE = 0
 	LD	A,(SLICE_SLICE)		; GET THE SLICE
 	OR	A			; SET FLAGS
-	JP	NZ, EXT_SLICE5C		; SLICE NOT ZERO - SIGNAL ERROR AND RETURN
+	JP	NZ,EXT_SLICE5C		; SLICE NOT ZERO - SIGNAL ERROR AND RETURN
 ;
 EXT_SLICE1A:
 	; RETURN MEDIA ID (NOT HD) WITH SUCCESS
@@ -5035,8 +5035,8 @@ EXT_SLICE3A
 ; STARTING SECTOR - THIS IS A COMPRIMISE - OUT OF SEQUENCE PARTITIONS ARE UNLIKELY.
 ;
 	PUSH	BC			; SAVE IT, BEING USED IN PARTITION LOOP
-        LD      BC, 4  			; IF NOT ALREADY SET - COPY 4 BYTES
-        LD      DE, SLICE_LBASIZ	; FROM PARTION LBA OFFSET (HL) - TO WORKING LBA SIZE (DE)
+        LD      BC,4  			; IF NOT ALREADY SET - COPY 4 BYTES
+        LD      DE,SLICE_LBASIZ		; FROM PARTION LBA OFFSET (HL) - TO WORKING LBA SIZE (DE)
         LDIR    			; COPY 4 BYTES
         POP	BC			; RESTORE
 ;
@@ -5047,10 +5047,10 @@ EXT_SLICE3A
 ;
 EXT_SLICE3B:
 	; FOUND CP/M (HD1K) PARTITION - RECORD THIS
-	LD	A, MID_HDNEW		; DISCOVERED HD1K MEDIA
-	LD	(SLICE_MID), A		; STORE IT
-	LD	BC, SPS_HD1K		; DISCOVERED HD1K MEDIA
-	LD	(SLICE_SPS), BC	; STORE IT
+	LD	A,MID_HDNEW		; DISCOVERED HD1K MEDIA
+	LD	(SLICE_MID),A		; STORE IT
+	LD	BC,SPS_HD1K		; DISCOVERED HD1K MEDIA
+	LD	(SLICE_SPS),BC		; STORE IT
 ;
 	; CAPTURE THE LBA OFFSET AND SECTOR COUNT FROM PARTITION
 	; HL POINTS TO PART LBA OFFSET FIELD OF PART ENTRY
@@ -5061,9 +5061,14 @@ EXT_SLICE3B:
 	JR	EXT_SLICE4A		; CONTINUE AND COMPUTE THE SLICE
 ;
 EXT_SLICE3C:
-	; NO PARTITION TABLE FOUND / NO CPM PARTITION FOUND -> HD512
-	LD	BC, SPS_HD512		; WITH HD512 SECTORS PER SLICE
-	LD	(SLICE_SPS), BC		; STORE IT
+	; NO PARTITION TABLE FOUND / NO CPM PARTITION
+	LD	A,(SLICE_SLICE)		; IF SLICE = 0, WE BOOT THE DISK ITSELF. IGNORE SLICE(S)
+	OR      A           		; SET FLAGS FOR SLICE ARGUMENT, IF SLICE==0
+	JR	Z,EXT_SLICE5Z		; BYPASS ALL CALCS / CHECKS - JUST BOOT THE DISK
+
+	; BOOT SLICE WITH LEGACY SPS
+	LD	BC,SPS_HD512		; WITH HD512 SECTORS PER SLICE
+	LD	(SLICE_SPS),BC		; STORE IT
 
 	; DID WE FIND AN OTHER (NOT CPM) PARTITION
 	LD	A,(SLICE_FND)		; HAVE WE ALREADY FOUND PROCESSED NON CPM
@@ -5071,16 +5076,16 @@ EXT_SLICE3C:
 	JR	NZ,EXT_SLICE4A		; MEDIA SIZE IS KNOWN BASED ON START OF PARTITION
 
 	; FIND THE PHYSICAL CAPCITY OF THE MEDIA CALL (DIOCAP)
-	LD      B, BF_DIOCAP    	; HBIOS FUNC: TO GET DISK LBA CAPACITY
-        LD      A, (SLICE_UNIT)
-	LD      C, A            	; PUT DISK UNIT IN C FOR FUNC CALL
+	LD      B,BF_DIOCAP    		; HBIOS FUNC: TO GET DISK LBA CAPACITY
+        LD      A,(SLICE_UNIT)
+	LD      C,A            		; PUT DISK UNIT IN C FOR FUNC CALL
 	CALL	DIO_DISPATCH		; DO IT - RETURNS SIZE in DE:HL
 	RET	NZ			; ABORT ON ERROR
 
 	; UPDATE LBA SIZE FROM MEDIA SIZE
-	LD	(SLICE_LBASIZ), HL	; LOWER ORDER BYTES - HL
+	LD	(SLICE_LBASIZ),HL	; LOWER ORDER BYTES - HL
 	EX	DE,HL
-	LD	(SLICE_LBASIZ+2), HL	; HIGHER ORDER BYTES - DE
+	LD	(SLICE_LBASIZ+2),HL	; HIGHER ORDER BYTES - DE
 ;
 EXT_SLICE4A:
 	; COMPUTE THE START SECTOR (RELATIVE) FOR SLICE -> DE:HL
@@ -5089,8 +5094,7 @@ EXT_SLICE4A:
 	LD	BC,(SLICE_SPS)
 	LD	A,(SLICE_SLICE)
 	OR      A           		; SLICE NUMBER - SET FLAGS TO CHECK LOOP CTR
-	;JR      Z,EXT_SLICE5A 		; NOTHING TO COUNT
-	JR	Z,EXT_SLICE6		; BYPASS CAPACITY CHECK IF SLICE == 0
+	JR      Z,EXT_SLICE5A 		; NOTHING TO COUNT
 EXT_SLICE4B:
 	ADD     HL,BC       		; ADD ONE SLICE (SPS) TO LOW WORD
 	JR      NC,EXT_SLICE4C 		; CHECK FOR CARRY
@@ -5104,8 +5108,8 @@ EXT_SLICE5A:
 	PUSH    HL			; SAVE THE SECTOR OFFSET (SPS * SLICE NUMBER)
 	PUSH    DE
 ;
-	ADD     HL, BC			; ADD SPS, GET REQUIRED CAPCITY (UPPER SECTOR)
-	JR      NC, EXT_SLICE5B
+	ADD     HL,BC			; ADD SPS, GET REQUIRED CAPCITY (UPPER SECTOR)
+	JR      NC,EXT_SLICE5B
 	INC     DE
 EXT_SLICE5B:
 	; DEHL HAS THE REQUIRED NUMBER OF SECTORS (ON MEDIA) FOR THE SLICE
@@ -5141,6 +5145,10 @@ EXT_SLICE5C:
 	OR      A
 	RET
 ;
+EXT_SLICE5Z:
+	LD      HL,0			; BOOT THE DISK TO LBA = 0
+	LD      DE,0			;
+;
 EXT_SLICE6:
 	; FINAL CALC AND RETURN SUCCESS
 	; ADD PARTITION OFFSET (START) TO DEHL TO GET ABSOLUTE SLICE OFFSET
@@ -5149,7 +5157,7 @@ EXT_SLICE6:
 	EX      DE,HL			; FLIP DE INTO HL
 	LD      BC,(SLICE_LBAOFF+2)	; MSB OF LBA OFFSET
 	ADC     HL,BC			; ADD MSB
-	EX      DE, HL			; FLIP BACK DE:HL AS SLICE OFFSET
+	EX      DE,HL			; FLIP BACK DE:HL AS SLICE OFFSET
 ;
 EXT_SLICE6A:
 	; SLICE FITS - RETURN CORRECTLY