Reset floppy disks upon read failure

Makefile

@@ -2,7 +2,7 @@ DOSBOX=dosbox -conf dosbox-build.conf -exit
 
 ordos.img: BOOT.BIN IO.SYS ORDOS.SYS COMMAND.COM debug.com edlin.com exe2bin.exe link.exe masm.exe
 	rm -f ordos.img
-	mkfs.fat -C $@ -M 0xff 320
+	mkfs.fat -C $@ 720
 	rw -I 0x7c00 -i BOOT.BIN -o $@ -c 512
 	mcopy -i $@ IO.SYS ::
 	mcopy -i $@ ORDOS.SYS ::

boot.asm

@@ -17,12 +17,12 @@ jmp code
 	dw 512 ; Bytes per sector
 	db 2 ; Sectors per cluster
 	dw 1 ; Reserved sectors
-	db 2 ; FATs
+fats db 2 ; FATs
 	dw 112 ; Root directory entries
-	dw 2*320 ; Total sectors
+	dw 2*720 ; Total sectors
-	db 0ffh ; Media descriptor
+	db 0f9h ; Media descriptor
-	dw 1 ; Sectors per fat
+sectorsperfat dw 3 ; Sectors per fat
-sectorspertrack dw 8
+sectorspertrack dw 9
 heads dw 2
 	dd 0 ; Hidden sectors
 	dd 0 ; Total sectors (large)
@@ -40,7 +40,7 @@ code:
 	mov drivenumber, dl
 
 	; TODO: Check we actually have the OS
-	mov ax, 10
+	mov ax, 14
 	mov bx, 600h
 	mov cx, 17 ; This is what PC-DOS 1.10's full size ends up at
 	call loadsectors

io.asm

@@ -1,6 +1,8 @@
 ; SPDX-License-Identifier: MIT
 ; Copyright (c) 2021 Juhani 'nortti' Krekelä.
 
+debug equ 1
+
 iosegment equ 60h
 dossegment equ iosegment + 1*1024/16 ; DOS starts 1KiB after IO system
 
@@ -64,8 +66,10 @@ init:
 	shl ax, cl
 	; Memory size is passed in dx
 	mov dx, ax
+if debug
 	call hexprint16
 	call newline
+endif
 
 	; Disk table is passed in si
 	mov si, offset iogroup:disks_table
@@ -94,9 +98,11 @@ init:
 	test al, al
 	jnz open_error
 
+if debug
 	mov al, '+'
 	mov ah, 0eh
 	int 10h
+endif
 
 	; Set random record field 0
 	mov word ptr iogroup:command_fcb+33, 0
@@ -114,12 +120,14 @@ init:
 	cmp al, 1
 	jne read_error
 
+if debug
 	mov ax, cx
 	call hexprint16
 
 	mov al, '.'
 	mov ah, 0eh
 	int 10h
+endif
 
 	; Set up segments for command.com
 	mov ds, bx
@@ -205,6 +213,7 @@ putch endp
 ; OUT:
 ;  TODO: Document
 diskread proc far
+if debug
 	push ax
 	mov ax, 0e00h + 'r'
 	int 10h
@@ -226,6 +235,7 @@ diskread proc far
 	call hexprint16
 	call newline
 	pop ax
+endif
 
 	; TODO: Everything except sregs can be trashed
 	push es
@@ -266,13 +276,25 @@ diskread proc far
 
 			dec di
 			jz sector_read_fail
+
+			reset_disk:
+if debug
+				mov al, '"'
+				mov ah, 0eh
+				int 10h
+endif
+				xor ax, ax
+				int 13h
+
 			pop cx
 			pop ax
 			jmp try_sector_read
 
 		sector_read_fail:
 			mov al, ah
+if debug
 			call hexprint8;debg
+endif
 			mov al, '?'
 			mov ah, 0eh
 			int 10h
@@ -532,7 +554,9 @@ error:
 	mov ah, 0eh
 	mov al, '!'
 	int 10h
+if debug
 	call far_caller
+endif
 
 hang:
 	hlt
@@ -544,14 +568,15 @@ code ends
 
 constants segment
 
-sectorspertrack dw 8 ; TODO: Don't hardcode
+sectorspertrack dw 9 ; TODO: Don't hardcode
 heads dw 2 ; TODO: Don't hardcode
 
 disks_table:
 	db 1 ; 1 drive, TODO: Don't hardcode
 
 	db 0 ; Physical drive 0
-	dw offset iogroup:parameters_320k
+	;dw offset iogroup:parameters_320k
+	dw offset iogroup:parameters_720k
 
 parameters_320k:
 	dw 512 ; Sector size in bytes
@@ -561,6 +586,14 @@ parameters_320k:
 	dw 112 ; Number of directory entries
 	dw 320*2 ; Number of sectors
 
+parameters_720k:
+	dw 512 ; Sector size in bytes
+	db 2 ; Sectors per cluster
+	dw 1 ; Number of reserved sectors
+	db 2 ; Number of FATs
+	dw 112 ; Number of directory entries
+	dw 720*2 ; Number of sectors
+
 doubleticks_per_hour dw 32772 ; 1800B0h / 2 / 24
 ticks_per_minute dw 1092 ; 1800B0h / 24 / 60
 ticks_per_second dw 18 ; 1800B0h / 24 / 60 / 60
@@ -583,6 +616,8 @@ days_since_epoch: dw 0
 data ends
 
 code segment
+if debug
+
 hexprint16 proc
 	xchg al, ah
 	call hexprint8
@@ -672,6 +707,7 @@ logaddr proc
 	ret
 logaddr endp
 
+endif
 code ends
 
 end