X-Git-Url: http://cloudbase.mooo.com/gitweb/avrcpm.git/blobdiff_plain/d305f8e44cff480b418bb67156fd1fe579ce5fa0..18be946b6d6633ccda8b9ab2d5894b23e815a63d:/avrcpm/avr/z80.asm

diff --git a/avrcpm/avr/z80.asm b/avrcpm/avr/z80.asm
index 2be56aa..64f0786 100644
--- a/avrcpm/avr/z80.asm
+++ b/avrcpm/avr/z80.asm
@@ -15,6 +15,9 @@
 ;
 ;    You should have received a copy of the GNU General Public License
 ;    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;
+;    $Id$
+;
 
 ;.nolist
 #if defined atmega8
@@ -40,12 +43,15 @@
 	#define BAUD   38400           /* console baud rate */
 #endif
  
+#define PARTID 0x52		/* Partition table id */
+				/* http://www.win.tue.nl/~aeb/partitions/partition_types-1.html */
 
 #define UBRR_VAL  ((F_CPU+BAUD*8)/(BAUD*16)-1)  /* clever rounding */
 
 #define	RXBUFSIZE 64		/* USART recieve buffer size. Must be power of 2 */
 #define	TXBUFSIZE 64		/* USART transmit buffer size. Must be power of 2 */
 
+#define DRAM_WAITSTATES 1	/* Number of additional clock cycles for dram read access */
 #define REFR_RATE   64000       /* dram refresh rate in cycles/s. */
 				/* Most drams need 1/15.6µs. */
 #define REFR_PRE    8           /* timer prescale factor */
@@ -53,11 +59,6 @@
 #define REFR_CNT    F_CPU / REFR_RATE / REFR_PRE
 
 
-#if defined __ATmega8__
-	.equ refr_vect = OC2addr
-#else
-	.equ refr_vect = OC2Aaddr
-#endif
 
 #define DRAM_WORD_ACCESS 0	/* experimental */
 
@@ -136,8 +137,6 @@
 .equ ZFL_C	=	0
 
 ;Register definitions
-.undef xl 		;r26
-.undef xh		;r27
 
 .def	_tmp	= r0	;  0
 .def	_0	= r1
@@ -164,8 +163,8 @@
 .def	oph	= r23	;
 .def	z_pcl	= r24	;
 .def	z_pch	= r25	;
-.def	adrl	= r26	;
-.def	adrh	= r27	;
+; xl 		;r26
+; xh		;r27
 ; yl		;r28
 ; yh		;r29
 ; zl		;r30	;
@@ -214,6 +213,7 @@
 .equ	UBRR0H	= UBRRH
 .equ	UBRR0L	= UBRRL
 .equ	OCR2A	= OCR2
+.equ	OC2Aaddr= OC2addr
 .equ	TCCR2A	= TCCR2
 .equ	TCCR2B	= TCCR2
 .equ	TIMSK1	= TIMSK
@@ -248,10 +248,25 @@
 
 
 
+;----------------------------------------
+; add wait states
+;	dram_wait  number_of_cycles
+
+.macro dram_wait
+.if @0 > 1
+	rjmp	PC+1
+	dram_wait @0 - 2
+.elif @0 > 0
+	nop
+	dram_wait @0 - 1
+.endif
+.endm
+
+
 .cseg
 .org 0
 	rjmp start		; reset vector
-.org refr_vect
+.org OC2Aaddr
 	rjmp refrint		; tim2cmpa
 .org OC1Aaddr   		; Timer/Counter1 Compare Match A
     	rjmp sysclockint	; 1ms system timer
@@ -279,6 +294,17 @@ start:
 	ldi temp,(1<<WDCE)
 	outm8	WDTCSR,temp
 
+; - Clear RAM
+
+	ldi	zl,low(SRAM_START)
+	ldi	zh,high(SRAM_START)
+	ldi	temp2,high(ramtop)
+clr_l:
+	st	z+,_0
+	cpi	zl,low(ramtop)
+	cpc	zh,temp2
+	brne	clr_l
+
 ; - Setup Ports
 	ldi 	temp,(1<<PUD)		;disable pullups
 	outm8	P_PUD,temp
@@ -298,13 +324,6 @@ start:
 
 ; - Init serial port
 
-	sts	rxcount,_0	; reset receive buffer
-	sts	rxidx_r,_0
-	sts	rxidx_w,_0
-	sts	txcount,_0	; reset transmit buffer
-	sts	txidx_r,_0
-	sts	txidx_w,_0
-	
 	ldi temp, (1<<TXEN0) | (1<<RXEN0) | (1<<RXCIE0)
 	outm8 UCSR0B,temp
 .ifdef URSEL
@@ -318,30 +337,8 @@ start:
 	ldi temp, LOW(UBRR_VAL)
 	outm8 UBRR0L,temp
 
-;Init timer2. Refresh-call should happen every (8ms/512)=312 cycles.
-
-	ldi	temp,REFR_CNT*2			; 2 cycles per int
-	outm8	OCR2A,temp
-	inm8	temp,TCCR2A
-	ori	temp,(1<<WGM21)			;CTC mode
-	outm8	TCCR2A,temp
-	inm8	temp,TCCR2B
-	ori	temp,REFR_CS			;clk/REFR_PRE
-	outm8	TCCR2B,temp
-	inm8	temp,TIMSK2
-	ori	temp, (1<<OCIE2A)
-	outm8	TIMSK2,temp
-
 ; Init clock/timer system
 
-	ldi	zl,low(timer_base)
-	ldi	zh,high(timer_base)
-	ldi	temp2,timer_size
-ti_loop:
-	st	z+,_0
-	dec	temp2
-	brne	ti_loop
-
 ; Init timer 1 as 1 ms system clock tick.
 
 	ldi	temp,high(F_CPU/1000)
@@ -354,6 +351,20 @@ ti_loop:
 	ori	temp,(1<<OCIE1A)
 	outm8	TIMSK1,temp
 
+;Init timer2. Refresh-call should happen every (8ms/512)=312 cycles.
+
+	ldi	temp,REFR_CNT*2			; 2 cycles per int
+	outm8	OCR2A,temp
+	inm8	temp,TCCR2A
+	ori	temp,(1<<WGM21)			;CTC mode
+	outm8	TCCR2A,temp
+	inm8	temp,TCCR2B
+	ori	temp,REFR_CS			;clk/REFR_PRE
+	outm8	TCCR2B,temp
+	inm8	temp,TIMSK2
+	ori	temp, (1<<OCIE2A)
+	outm8	TIMSK2,temp
+
 	sei
 
 
@@ -367,23 +378,18 @@ ti_loop:
 	.db "CPM on an AVR, v1.0",13,0,0
 
 
-	rcall printstr
-	.db "Initing mmc...",13,0
-	rcall mmcInit
-
-
 .if MEMTEST
 	rcall printstr
 	.db "Testing RAM: fill...",0,0
 
 ;Fill RAM
-	ldi adrl,0
-	ldi adrh,0
+	ldi xl,0
+	ldi xh,0
 ramtestw:
-	mov temp,adrh
-	eor temp,adrl
+	mov temp,xh
+	eor temp,xl
 	rcall memwritebyte
-	adiw adrl,1
+	adiw xl,1
 	brcc ramtestw
 	rcall printstr
 	.db "wait...",0
@@ -399,61 +405,167 @@ ramtestwl:
 	.db "reread...",13,0,0
 
 ;re-read RAM
-	ldi adrl,0
-	ldi adrh,0
+	ldi xl,0
+	ldi xh,0
 ramtestr:
 	rcall memReadByte
-	mov temp2,adrh
-	eor temp2,adrl
+	mov temp2,xh
+	eor temp2,xl
 	cp temp,temp2
 	breq ramtestrok
 	rcall printhex
 	ldi temp,'<'
 	rcall uartPutc
-	mov temp,adrh
-	eor temp,adrl
+	mov temp,xh
+	eor temp,xl
 	rcall printhex
 	ldi temp,'@'
 	rcall uartPutc
-	mov temp,adrh
+	mov temp,xh
 	rcall printhex
-	mov temp,adrl
+	mov temp,xl
 	rcall printhex
 	ldi temp,13
 	rcall uartPutc
 ramtestrok:
-	adiw adrl,1
+	adiw xl,1
 	brcc ramtestr
 
 .endif
 
 .if MEMFILL_CB
 	;Fill ram with cbs, which (for now) will trigger an invalid opcode error.
-	ldi adrl,0
-	ldi adrh,0
+	ldi xl,0
+	ldi xh,0
 ramfillw:
 	ldi temp,0xcb
 	rcall memwritebyte
-	adiw adrl,1
+	adiw xl,1
 	brcc ramfillw
 .endif
 
 
+	rcall printstr
+	.db "Initing mmc...",13,0
+	rcall mmcInit
+
+;----------------------------------------------------------------------------
+
+; Partition table offsets:
+#define PART_TYPE   4
+#define PART_START  8
+#define PART_SIZE  12
+
+;Load first sector from MMC (boot sector)
 
-;Load initial sector from MMC (512 bytes)
-	ldi adrh,0
-	ldi adrl,0
-	rcall mmcReadSect
+boot_again:
+	ldi	yh,0
+	ldi	yl,0
+	ldi	xh,0
+	ldi	xl,0
+	rcall	mmcReadSect
+
+;Test, if it has a valid MBR
+
+	lds	temp,hostbuf+510	;MBR signature (0xAA55)  at and of sector?
+	lds	temp2,hostbuf+511
+	ldi	temp4,0xAA
+	cpi	temp,0x55		
+	cpc	temp2,temp4
+	breq	boot_part
+
+;No MBR, no partition table ...
+	ldi	opl,1
+	sts	ndisks,opl
+	rjmp	boot_ipl
+		
+;Search Partition Table for CP/M partitions
+boot_part:
+	ldi	zl,low(hostbuf+510-64)
+	ldi	zh,high(hostbuf+510-64)
+	ldi	yl,low(hostdstart)
+	ldi	yh,high(hostdstart)
+	ldi	opl,0
+	ldi	oph,high(hostbuf+510)
+boot_ploop:
+	ldd	temp,z+PART_TYPE
+	cpi	temp,PARTID
+	brne	boot_nextp
+	
+	ldd	temp,z+PART_START
+	st	y+,temp
+	ldd	temp2,z+PART_START+1
+	st	y+,temp2
+	ldd	temp3,z+PART_START+2
+	st	y+,temp3
+	ldd	temp4,z+PART_START+3
+	st	y+,temp4
+	
+	rcall	printstr
+	.db	"CP/M partition at: ",0
+	rcall	print_ultoa
+	rcall	printstr
+	.db	", size: ",0,0
+	ldd	temp,z+PART_SIZE
+	ldd	temp2,z+PART_SIZE+1
+	ldd	temp3,z+PART_SIZE+2
+	ldd	temp4,z+PART_SIZE+3
+	lsr	temp4
+	ror	temp3
+	ror	temp2
+	ror	temp
+	rcall	print_ultoa
+	rcall	printstr
+	.db	"KB.",13,0,0
+	
+	inc	opl
+	cpi	temp2,MAXDISKS
+	breq	boot_pend	
+boot_nextp:
+	adiw	zl,16
+	cpi	zl,low(hostbuf+510)
+	cpc	zh,oph
+	brsh	boot_pend
+	rjmp	boot_ploop
+boot_pend:
+	sts	ndisks,opl
+
+; Read first sector of first CP/M partition
+
+	lds	xl,hostdstart
+	lds	xh,hostdstart+1
+	lds	yl,hostdstart+2
+	lds	yh,hostdstart+3
+	rcall	mmcReadSect
+
+boot_ipl:
+	lds	opl,ndisks
+	tst	opl
+	brne	boot_ipl2
+	rcall	printstr
+	.db	"No bootable CP/M disk found! Please change MMC/SD-Card",13,0
+	ldi	temp2,18
+boot_wl:
+	ldi	temp,255
+	rcall	delay_ms
+	dec	temp2
+	brne	boot_wl
+	rjmp	boot_again
+	
+
+boot_ipl2:
+
+;First sector of disk or first CP/M partition is in hostbuf.
 
 ;Save to Z80 RAM (only 128 bytes because that's retro)
 	ldi zl,low(hostbuf)
 	ldi zh,high(hostbuf)
-	ldi adrh,0x20
-	ldi adrl,0x00
+	ldi xh,0x20
+	ldi xl,0x00
 iplwriteloop:
 	ld temp,z+
 	rcall memWriteByte
-	adiw adrl,1
+	adiw xl,1
 	cpi zl,low(hostbuf+128)
 	brne iplwriteloop
 	cpi zh,high(hostbuf+128)
@@ -499,7 +611,7 @@ noprintpc:
 .endif
 
 	; *** Stage 1: Fetch next opcode
-	movw adrl,z_pcl
+	movw xl,z_pcl
 	rcall memReadByte
 
 
@@ -642,8 +754,8 @@ notrace6:
 ;18 	- Sector select
 ;20 	- Write addr l
 ;21 	- Write addr h
-;22 	- Trigger - write 1 to read, 2 to write a sector using the above info;
-;			3 - 5, write to allocated/dirctory/unallocated
+;22 	- Trigger - write  to read, to write a sector using the above info;
+;			, write to allocated/dirctory/unallocated
 
 	.equ	READ_FUNC  = 7
 	.equ	WRITE_FUNC = 6
@@ -655,6 +767,7 @@ notrace6:
 ;*****************************************************
 ;*         CP/M to host disk constants               *
 ;*****************************************************
+	.equ	MAXDISKS  = 4		;Max number of Disks (partitions)
 	.equ	blksize = 1024		;CP/M allocation size
 	.equ	hostsize = 512		;host disk sector size
 ;	.equ	hostspt = 20		;host disk sectors/trk
@@ -674,13 +787,15 @@ notrace6:
 
 
 	.dseg
+ndisks:		.byte	1	;Number of CP/M disks
 
 seekdsk:	.byte	1	;seek disk number
 seektrk:	.byte	2	;seek track number
 seeksec:	.byte	1	;seek sector number
 
 hostdsk:	.byte	1	;host disk number
-hostlba:	.byte	2	;host track number
+hostlba:	.byte	3	;host sector number (relative to partition start)
+hostdstart:	.byte	4*MAXDISKS ; host disks start sector (partition)
 
 unacnt:		.byte	1	;unalloc rec cnt
 unadsk:		.byte	1	;last unalloc disk
@@ -702,6 +817,9 @@ portRead:
 	cpi temp2,1
 	breq conInp
 
+	cpi	temp2,15
+	breq	dskDiskCheck
+
 	cpi	temp2,TIMER_MSECS
 	brlo	pr_noclock
 	cpi	temp2,TIMER_MSECS+6
@@ -718,6 +836,9 @@ portWrite:
 	breq dbgOut
 	cpi temp2,2
 	breq conOut
+
+	cpi temp2,15
+	breq dskDiskSel
 	cpi temp2,16
 	breq dskTrackSel_l
 	cpi temp2,17
@@ -765,6 +886,18 @@ conOut:
 	rjmp uartputc
 
 
+dskDiskCheck:
+	lds	temp,seekdsk
+	lds	temp2,ndisks	;check if selected disk # is less then # of disks
+	cp	temp,temp2
+	ldi	temp,0
+	brlt	PC+2
+	ldi	temp,0xff		;error return
+	ret
+
+dskDiskSel:
+	sts seekdsk,temp
+	ret
 
 dskTrackSel_l:
 	sts seektrk,temp
@@ -968,50 +1101,50 @@ dsk_rwoper:
 
 	;Convert track/sector to an LBA address (in 128byte blocks)
 
-	lds	adrl,seeksec		;
-	ldi	adrh,0			;
+	lds	xl,seeksec		;
+	ldi	xh,0			;
+	ldi	yl,0			;
 	lds	temp3,seektrk		;
 	lds	temp4,seektrk+1		;
 	ldi	temp,CPMSPT		;
 	mul	temp3,temp		;
-	add	adrl,r0			;
-	adc	adrh,r1			;
+	add	xl,r0			;
+	adc	xh,r1			;
 	mul	temp4,temp		;
-	add	adrh,r0			;adrh:adrl := sec + trk * SectorsPerTrack
+	add	xh,r0			;xh:xl := sec + trk * SectorsPerTrack
+	adc	yl,r1			;
 	clr	_0
 
-	mov	temp,adrl
+	mov	temp,xl
 	andi	temp,SECMSK		;mask buffer number
 	push	temp			;save for later
-.if DISK_DEBUG
-	rcall printstr
-	.db "; bufnr: ",0,0
-	rcall printhex
-.endif
 
 	;Convert from CP/M LBA blocks to host LBA blocks
 	ldi temp,SECSHF
 dsk_sh1:
-	lsr	adrh
-	ror	adrl
+	lsr	xh
+	ror	xl
+	ror	yl
 	dec	temp
 	brne	dsk_sh1
-					;adrh:adrl = host block to seek
+					;yl:xh:xl = host block to seek
 ;	active host sector?
 	sbis	flags,hostact		;host active?
 	 rjmp	dsk_filhst		;fill host if not
 
 ;	host buffer active, same as seek buffer?
 	lds	temp,seekdsk
-	lds	temp3,hostdsk		;same disk?
-	cp	temp,temp3		;seekdsk = hostdsk?
+	lds	temp2,hostdsk		;same disk?
+	cp	temp,temp2		;seekdsk = hostdsk?
 	brne	dsk_nomatch
 
 ;	same disk, same block?
-	lds	temp3,hostlba
-	lds	temp4,hostlba+1
-	cp	adrl,temp3
-	cpc	adrh,temp4	
+	lds	temp,hostlba
+	lds	temp2,hostlba+1
+	lds	temp3,hostlba+2
+	cp	xl,temp
+	cpc	xh,temp2
+	cpc	yl,temp3
 	breq	dsk_match
 ;
 dsk_nomatch:
@@ -1023,8 +1156,9 @@ dsk_filhst:
 	;may have to fill the host buffer
 	lds	temp,seekdsk
 	sts	hostdsk,temp
-	sts	hostlba,adrl
-	sts	hostlba+1,adrh
+	sts	hostlba,xl
+	sts	hostlba+1,xh
+	sts	hostlba+2,yl
 
 	sbic	flags,rsflag		;need to read?
 	 rcall	dsk_readhost		;yes, if 1
@@ -1054,31 +1188,29 @@ dsk_match:
 .endif
 	clr	_0
 
-	lds	adrl,dmaadr
-	lds	adrh,dmaadr+1
-	push	yl
-	ldi	yl,128			;length of move
+	lds	xl,dmaadr
+	lds	xh,dmaadr+1
+	ldi	temp3,128			;length of move
 	sbic	flags,readop		;which way?
 	 rjmp	dsk_rmove		;skip if read
 
 ;	mark write operation
 	sbi	flags,hostwrt		;hostwrt = 1
 dsk_wmove:
-	rcall memReadByte
-	st z+,temp
-	adiw adrl,1
-	dec yl
+	rcall	memReadByte
+	st	z+,temp
+	adiw	xl,1
+	dec	temp3
 	brne dsk_wmove
 	rjmp	dsk_rwmfin
 	
 dsk_rmove:
 	ld	temp,z+
 	rcall	memWriteByte
-	adiw	adrl,1
-	dec	yl
+	adiw	xl,1
+	dec	temp3
 	brne	dsk_rmove
 dsk_rwmfin:
-	pop	yl
 ;	data has been moved to/from host buffer
 	lds	temp,wrtype	;write type
 	cpi	temp,WRDIR	;to directory?
@@ -1115,13 +1247,34 @@ dsk_writehost:
 	;error flag in erflag.
 	;Return erflag non-zero if error
 	
-	push	adrh
-	push	adrl
-	lds	adrl,hostlba
-	lds	adrh,hostlba+1
+	push	yh
+	push	yl
+	push	xh
+	push	xl
+	ldi	zl,low(hostdstart)
+	ldi	zh,high(hostdstart)
+	lds	temp,hostdsk
+	lsl	temp
+	lsl	temp
+	add	zl,temp
+	adc	zh,_0
+	
+	ldd	xl,z+0
+	ldd	xh,z+1
+	ldd	yl,z+2
+	ldd	yh,z+3
+	lds	temp,hostlba
+	add	xl,temp
+	lds	temp,hostlba+1
+	adc	xh,temp
+	lds	temp,hostlba+2
+	adc	zl,temp
+	adc	zh,_0
 	rcall	mmcWriteSect
-	pop	adrl
-	pop	adrh
+	pop	xl
+	pop	xh
+	pop	yl
+	pop	yh
 	sts	erflag,_0
 	ret
 
@@ -1130,13 +1283,34 @@ dsk_readhost:
 	;Read "hostsiz" bytes into hostbuf and return 
 	;error flag in erflag.
 
-	push	adrh
-	push	adrl
-	lds	adrl,hostlba
-	lds	adrh,hostlba+1
+	push	yh
+	push	yl
+	push	xh
+	push	xl
+	ldi	zl,low(hostdstart)
+	ldi	zh,high(hostdstart)
+	lds	temp,hostdsk
+	lsl	temp
+	lsl	temp
+	add	zl,temp
+	adc	zh,_0
+
+	ldd	xl,z+0
+	ldd	xh,z+1
+	ldd	yl,z+2
+	ldd	yh,z+3
+	lds	temp,hostlba
+	add	xl,temp
+	lds	temp,hostlba+1
+	adc	xh,temp
+	lds	temp,hostlba+2
+	adc	zl,temp
+	adc	zh,_0
 	rcall	mmcReadSect
-	pop	adrl
-	pop	adrh
+	pop	xl
+	pop	xh
+	pop	yl
+	pop	yh
 	sts	erflag,_0
 	ret
 
@@ -1150,8 +1324,6 @@ mmcByteNoSend:
 mmcByte:
 
 .if MMC_DEBUG
-	push zl
-	push zh
 	rcall printstr
 	.db "MMC: <--",0
 	rcall printhex
@@ -1165,15 +1337,11 @@ mmcWrByteW:
 	in temp,SPDR
 
 .if MMC_DEBUG
-	push temp
 	rcall printstr
 	.db ", -->",0
 	rcall printhex
 	rcall printstr
 	.db ".",13,0
-	pop temp
-	pop zh
-	pop zl
 .endif
 	ret
 
@@ -1310,8 +1478,8 @@ mmcInitOcrLoopDone:
 	ret
 
 
-;Call this with adrh:adrl = sector number
-;16bit lba address means a max reach of 32M.
+;Call this with yh:yl:xh:xl = sector number
+;
 mmcReadSect:
 	ldi temp,0x50
 	out SPCR,temp
@@ -1320,14 +1488,14 @@ mmcReadSect:
 	rcall mmcByteNoSend
 	ldi temp,0x51	;cmd (read sector)
 	rcall mmcByte
-	ldi temp,0
-	lsl adrl
-	rol adrh
-	rol temp
+	lsl	xl			;convert to byte address (*512)
+	rol	xh
+	rol 	yl
+	mov	temp,yl
 	rcall mmcByte
-	mov temp,adrh ;pxl
+	mov temp,xh ;pxl
 	rcall mmcByte
-	mov temp,adrl ;pyh
+	mov temp,xl ;pyh
 	rcall mmcByte
 	ldi temp,0  ;pyl
 	rcall mmcByte
@@ -1366,8 +1534,8 @@ mmcreadloop:
 	ret
 
 
-;Call this with adrh:adrl = sector number
-;16bit lba address means a max reach of 32M.
+;Call this with yh:yl:xh:xl = sector number
+;
 mmcWriteSect:
 	ldi temp,0x50
 	out SPCR,temp
@@ -1377,14 +1545,14 @@ mmcWriteSect:
 
 	ldi temp,0x58	;cmd (write sector)
 	rcall mmcByte
-	ldi temp,0
-	lsl adrl
-	rol adrh
-	rol temp
+	lsl	xl			;convert to byte address (*512)
+	rol	xh
+	rol 	yl
+	mov	temp,yl
 	rcall mmcByte
-	mov temp,adrh ;pxl
+	mov temp,xh ;pxl
 	rcall mmcByte
-	mov temp,adrl ;pyh
+	mov temp,xl ;pyh
 	rcall mmcByte
 	ldi temp,0  ;pyl
 	rcall mmcByte
@@ -1463,24 +1631,24 @@ resetwait:
 	out P_AH,temp
 .endm
 
-;Loads the byte on address adrh:adrl into temp.
-;must not alter adrh:adrl
+;Loads the byte on address xh:xl into temp.
+;must not alter xh:xl
 
 dram_read:
 	cli
-	DRAM_SETADDR adrh, ~0,(1<<ram_ras), ~(1<<ram_a8), (1<<ram_oe)
+	DRAM_SETADDR xh, ~0,(1<<ram_ras), ~(1<<ram_a8), (1<<ram_oe)
 	cbi P_RAS,ram_ras
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
 	cbi P_CAS,ram_cas
 	cbi P_A8,ram_a8
-	nop
+	dram_wait DRAM_WAITSTATES	;
 	in  temp,P_DQ-2		; PIN
 	sbi P_CAS,ram_cas
 
 	cbi P_CAS,ram_cas
 	andi temp,0x0f
 	swap temp
-	nop
+	dram_wait DRAM_WAITSTATES	;
 	in  temp2,P_DQ-2	; PIN
 	andi temp2,0x0f
 	or  temp,temp2
@@ -1493,12 +1661,12 @@ dram_read:
 
 #if DRAM_WORD_ACCESS
 dram_read_w:
-	cpi adrl,255
+	cpi xl,255
 	brne dram_read_w1
 	
 	rcall dram_read
 	push temp
-	adiw adrl,1
+	adiw xl,1
 	rcall dram_read
 	mov temp2,temp
 	pop temp
@@ -1506,9 +1674,9 @@ dram_read_w:
 
 dram_read_w1:
 	cli
-	DRAM_SETADDR adrh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
+	DRAM_SETADDR xh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
 	cbi P_RAS,ram_ras
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
 	cbi P_CAS,ram_cas
 	cbi P_A8,ram_a8
 	nop
@@ -1525,8 +1693,8 @@ dram_read_w1:
 	
 ;	push temp
 	mov _wl,temp
-	inc adrl
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
+	inc xl
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_oe)), (1<<ram_a8)
 	cbi P_CAS,ram_cas
 	cbi P_A8,ram_a8
 	nop
@@ -1549,8 +1717,8 @@ dram_read_w1:
 	ret
 #endif
 
-;Writes the byte in temp to  adrh:adrl
-;must not alter adrh:adrl
+;Writes the byte in temp to  xh:xl
+;must not alter xh:xl
 
 dram_write:
 	cli
@@ -1561,9 +1729,9 @@ dram_write:
 	andi temp,RAM_DQ_MASK & ~(1<<ram_w)
 	ori temp,(1<<ram_cas)
 	out PORTC,temp
-	DRAM_SETADDR adrh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
+	DRAM_SETADDR xh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
 	cbi P_RAS,ram_ras
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
 	cbi PORTC,ram_cas
 	sbi PORTC,ram_cas
 
@@ -1585,13 +1753,13 @@ dram_write:
 
 #if DRAM_WORD_ACCESS
 dram_write_w:
-	cpi adrl,255
+	cpi xl,255
 	brne dram_write_w1
 	
 	push temp2
 	rcall dram_write
 	pop temp
-	adiw adrl,1
+	adiw xl,1
 	rcall dram_write
 	ret	
 
@@ -1606,9 +1774,9 @@ dram_write_w1:
 	ori temp,(1<<ram_cas)
 	out PORTC,temp
 
-	DRAM_SETADDR adrh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
+	DRAM_SETADDR xh, ~0,(1<<ram_ras), ~(1<<ram_a8),(1<<ram_oe)
 	cbi P_RAS,ram_ras
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
 	cbi PORTC,ram_cas
 	sbi PORTC,ram_cas
 
@@ -1623,13 +1791,13 @@ dram_write_w1:
 	sbi PORTC,ram_cas
 
 	pop temp
-	inc adrl
+	inc xl
 	mov  temp2,temp
 	andi temp,RAM_DQ_MASK & ~(1<<ram_w)
 	ori temp,(1<<ram_cas)
 	out PORTC,temp
 
-	DRAM_SETADDR adrl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
+	DRAM_SETADDR xl, ~(1<<ram_ras),0, ~((1<<ram_a8)),(1<<ram_oe)
 	cbi PORTC,ram_cas
 	sbi PORTC,ram_cas
 
@@ -1663,6 +1831,7 @@ refrint:
 ;	nop			;1      |0   |0   
 	sbi P_RAS,ram_ras	;2      |0   |0   
 				;       |0   |0   
+	dram_wait DRAM_WAITSTATES-1	;
 ;	nop			;1      |0   |0   
 	cbi P_RAS,ram_ras	;2      |0    1|  
 				;       |0    1|  
@@ -1672,7 +1841,6 @@ refrint:
 				;        1|   1|  
 	reti			;4  --> 21 cycles
 
-; ****************************************************************************
 
 ; ------------- system timer 1ms ---------------
     .dseg
@@ -2107,6 +2275,7 @@ rxfifo:
 txfifo:
 	.byte	TXBUFSIZE
 
+ramtop:		
 	.cseg
 
 ; Save received character in a circular buffer. Do nothing if buffer overflows.
@@ -2341,53 +2510,53 @@ do_fetch_sp:
 	ret
 
 do_fetch_mbc:
-	movw adrl,z_c
+	movw xl,z_c
 	rcall memReadByte
 	mov opl,temp
 	ret
 
 do_fetch_mde:
-	movw adrl,z_e
+	movw xl,z_e
 	rcall memReadByte
 	mov opl,temp
 	ret
 
 do_fetch_mhl:
-	movw adrl,z_l
+	movw xl,z_l
 	rcall memReadByte
 	mov opl,temp
 	ret
 
 do_fetch_msp:
-	movw adrl,z_spl
+	movw xl,z_spl
 #if DRAM_WORD_ACCESS
 	rcall memReadWord
 	movw opl,temp
 #else
 	rcall memReadByte
 	mov opl,temp
-	adiw adrl,1
+	adiw xl,1
 	rcall memReadByte
 	mov oph,temp
 #endif	
 	ret
 
 do_fetch_dir8:
-	movw adrl,z_pcl
+	movw xl,z_pcl
 	rcall memReadByte
 	adiw z_pcl,1
 	mov opl,temp
 	ret
 
 do_fetch_dir16:
-	movw adrl,z_pcl
+	movw xl,z_pcl
 #if DRAM_WORD_ACCESS
 	rcall memReadWord
 	movw opl,temp
 #else
 	rcall memReadByte
 	mov opl,temp
-	adiw adrl,1
+	adiw xl,1
 	rcall memReadByte
 	mov oph,temp
 #endif	
@@ -2395,9 +2564,9 @@ do_fetch_dir16:
 	ret
 
 do_fetch_rst:
-	movw adrl,z_pcl
-	subi adrl,1
-	sbci adrh,0
+	movw xl,z_pcl
+	subi xl,1
+	sbci xh,0
 	rcall memReadByte
 	andi temp,0x38
 	ldi oph,0
@@ -2507,32 +2676,32 @@ do_store_hl:
 	ret
 
 do_store_mbc:
-	movw adrl,z_c
+	movw xl,z_c
 	mov temp,opl
 	rcall memWriteByte
 	ret
 
 do_store_mde:
-	movw adrl,z_e
+	movw xl,z_e
 	mov temp,opl
 	rcall memWriteByte
 	ret
 
 do_store_mhl:
-	movw adrl,z_l
+	movw xl,z_l
 	mov temp,opl
 	rcall memWriteByte
 	ret
 
 do_store_msp:
-	movw adrl,z_spl
+	movw xl,z_spl
 #if DRAM_WORD_ACCESS
 	movw temp,opl
 	rcall memWriteWord
 #else
 	mov temp,opl
 	rcall memWriteByte
-	adiw adrl,1
+	adiw xl,1
 	mov temp,oph
 	rcall memWriteByte
 #endif
@@ -2561,7 +2730,7 @@ do_store_call:
 	ret
 
 do_store_am:
-	movw adrl,opl
+	movw xl,opl
 	mov temp,z_a
 	rcall memWriteByte
 	ret
@@ -2843,13 +3012,13 @@ opjumps:
 ;----------------------------------------------------------------
 
 
-.equ AVR_T = 6
-.equ AVR_H = 5
-.equ AVR_S = 4
-.equ AVR_V = 3
-.equ AVR_N = 2
-.equ AVR_Z = 1
-.equ AVR_C = 0
+.equ AVR_T = SREG_T
+.equ AVR_H = SREG_H
+.equ AVR_S = SREG_S
+.equ AVR_V = SREG_V
+.equ AVR_N = SREG_N
+.equ AVR_Z = SREG_Z
+.equ AVR_C = SREG_C
 
 ;------------------------------------------------;
 ; Move single bit between two registers
@@ -3251,14 +3420,14 @@ do_op_addhl:
 ;
 ;
 do_op_sthl: ;store hl to mem loc in opl:h
-	movw adrl,opl
+	movw xl,opl
 #if DRAM_WORD_ACCESS
 	movw temp,z_l
 	rcall memWriteWord
 #else
 	mov temp,z_l
 	rcall memWriteByte
-	adiw adrl,1
+	adiw xl,1
 	mov temp,z_h
 	rcall memWriteByte
 #endif
@@ -3271,14 +3440,14 @@ do_op_sthl: ;store hl to mem loc in opl:h
 ;
 ; 
 do_op_rmem16:
-	movw adrl,opl
+	movw xl,opl
 #if DRAM_WORD_ACCESS
 	rcall memReadWord
 	movw opl,temp
 #else
 	rcall memReadByte
 	mov opl,temp
-	adiw adrl,1
+	adiw xl,1
 	rcall memReadByte
 	mov oph,temp
 #endif	
@@ -3291,7 +3460,7 @@ do_op_rmem16:
 ;
 ;
 do_op_rmem8:
-	movw adrl,opl
+	movw xl,opl
 	rcall memReadByte
 	mov opl,temp
 	ret
@@ -3476,17 +3645,17 @@ do_op_cpl:
 ;
 ;
 do_op_push16:
-	movw adrl,z_spl
-	subi adrl,2
-	sbci adrh,0
-	movw z_spl,adrl
+	movw xl,z_spl
+	subi xl,2
+	sbci xh,0
+	movw z_spl,xl
 #if DRAM_WORD_ACCESS	
 	movw temp,opl
 	rcall memWriteWord
 #else
 	mov temp,opl
 	rcall memWriteByte
-	adiw adrl,1
+	adiw xl,1
 	mov temp,oph
 	rcall memWriteByte
 #endif
@@ -3518,14 +3687,14 @@ do_op_push16:
 ;
 ;
 do_op_pop16:
-	movw adrl,z_spl
+	movw xl,z_spl
 #if DRAM_WORD_ACCESS
 	rcall memReadWord
 	movw opl,temp
 #else
 	rcall memReadByte
 	mov opl,temp
-	adiw adrl,1
+	adiw xl,1
 	rcall memReadByte
 	mov oph,temp
 #endif