X-Git-Url: http://cloudbase.mooo.com/gitweb/ddt180.git/blobdiff_plain/1d3941c8ac130b6dcf7951cb13c0b8c8e46a8e11..HEAD:/ddt180.z80

diff --git a/ddt180.z80 b/ddt180.z80
index 8e3ad31..c1a394b 100644
--- a/ddt180.z80
+++ b/ddt180.z80
@@ -7,31 +7,11 @@
 ;   - Cut the .PRL header (first 256 byte) end rename the result to DDTZ.COM.
 
 ;-------------------------------------------------------------------------------
-; Relocation loader
-;
-TPA	equ	0100h
-	cseg
-	.phase	TPA
-
-	jp	start
-	ds	3
-
-ldr_end:
-ldr_size	equ	$ - TPA
-current_phase	defl	$
-
-	.dephase
-current_cseg	defl	$
-
-;-------------------------------------------------------------------------------
-; DDT/Z core
-;
-
 ; Some greneral definitions
 
-TAB		equ	9
-LF		equ	10
-CR		equ	13
+TAB		equ	09h
+CR		equ	0dh
+LF		equ	0ah
 
 ; CP/M memory layout
 
@@ -58,7 +38,7 @@ BDOS_SETDMA	equ	26      ;Set DMA Address
 
 ; ddtz specific definitions
 
-STACK_SIZE	equ	64	;ddtz internal stack
+STACK_SIZE	equ	80	;ddtz internal stack
 CONBUF_SIZE	equ	80	;Size of console input buffer
 EXPR_BUF_SIZE	equ	128	;expressen buffer for conditional breakpoints
 BP_CNT		equ	12	;Number of breakpoints
@@ -70,12 +50,32 @@ SYMCASE_CONV	equ	1	;Convert case when symbols are loaded
 SYMCASE_LOWER	equ	2	;Convert to lower case if set, else to upper case
 
 ;-------------------------------------------------------------------------------
+; Relocation loader
+;
+TPA	equ	0100h
+	cseg
+	.phase	TPA
+
+	jp	start
+	ds	3
+
+ldr_end:
+ldr_size	equ	$ - TPA
+current_phase	defl	$
+
+	.dephase
+current_cseg	defl	$
+
+;-------------------------------------------------------------------------------
+; DDT/Z core
+;
+
 
 ddtz_base:
 	jp ddtz_bdos
 l0003h:
-	rst 30h
-sub_0004h:
+	rst 30h			;rst used by ddtz
+di_or_ei:			;ints enabled/disabled while ddtz is running
 	nop
 	ret
 ddtz_bdos:
@@ -135,18 +135,18 @@ reg.pc:	dw	TPA
 var.$:	dw	0000h
 var.@:	dw	0
 
-error_func:dw	l0146h
+error_func:dw	p_msg_error
 cmd_rpt:dw	mainloop
 
+;-------------------------------------------------------------------------------
+
 conbuf:
 	db	CONBUF_SIZE
 
 	ld sp,stack
 	exx
 	ld de,ddtz_base
-	or a
-	sbc hl,de
-	add hl,de
+	call cp_hl_de
 	jr c,l0079h
 	ex de,hl
 l0079h:
@@ -168,7 +168,7 @@ l007ch:
 	ld a,0fbh
 l0093h:
 	ld (reg.iff),a
-	call sub_0004h
+	call di_or_ei
 	ld hl,ddtz_base
 	ld l,000h
 	ld (reg_sp),hl
@@ -181,6 +181,8 @@ l0093h:
 
 	ds	CONBUF_SIZE + 3 - ($ - conbuf)
 
+;-------------------------------------------------------------------------------
+
 CMDTAB:
 	dw	cmd_@		;examine/substitute the displacement register @
 	dw	cmd_A		;Assemble
@@ -210,15 +212,21 @@ CMDTAB:
 	dw	cmd_Y		;examine [and substitute] Y variables
 	dw	cmd_Z		;Zap (fill) memory with a byte string
 
+ERROR:
+	ld hl,(error_func)
+exe_hl:
+	call CALL_HL
+	;fall thru
 mainloop:
 	ld sp,stack
-	ld hl,l0146h
+	ld hl,p_msg_error
 	ld (error_func),hl
 	ld hl,(reg.pc)
 	ld (var.$),hl
 	call bp_clr_temporary
 	ld hl,(cmd_rpt)
 	ld de,mainloop
+	ld (cmd_rpt),de
 	call cp_hl_de
 	ld a,'>'
 	call outchar
@@ -227,38 +235,31 @@ mainloop:
 	call get_line
 	call skipbl
 	jr z,exe_hl
-	ld hl,mainloop
-	ld (cmd_rpt),hl
 	inc de
 	sub '@'
 	jr c,ERROR
 	cp 'Z'+1-'@'
 	jr nc,ERROR
-	add a,a
 	ld hl,CMDTAB
-	call add_hl_a
+	call add_hl_a2
 	ld a,(hl)
 	inc hl
 	ld h,(hl)
 	ld l,a
 	jr exe_hl
 
-ERROR:
-	ld hl,(error_func)
-exe_hl:
-	call CALL_HL
-	jr mainloop
+;-------------------------------------------------------------------------------
 
-l0146h:
+p_msg_error:
 	call	pstr_inl
 	dc	'?'
 	;fall thru
 crlf:
 	call	pstr_inl
-	db	CR,LF+80h
-	call inchar
-	ld a,0
+	dc	CR,LF
+	xor a
 	ld (con_col),a
+	call inchar
 	jr c,mainloop
 	ret
 
@@ -284,13 +285,12 @@ l01bfh:
 sub_01d9h:
 	call	pstr_inl
 	dc	'-'
-	dec hl
-	jp cpl.hl
+	jp neg.hl
 
 out_hl_dec_neg:
 	push hl
 	call sub_01d9h
-	defb 03eh
+	defb 03eh		;ld a,..  swallow push hl
 out.hl.dec:
 	push hl
 	ld b,006h
@@ -337,12 +337,10 @@ out_hex:
 	pop af
 
 out_dgt:
-	and 0fh
-	cp 10
-	jr c,l0229h
-	add a,007h
-l0229h:
-	add a,'0'
+	or	0f0h
+	daa
+	add	a,0a0h
+	adc	a,040h
 	jr outchar
 
 out.bin.w:
@@ -352,11 +350,10 @@ out.bin.w:
 out.bin.b:
 	ld b,8
 l01c9h:
-	add a,a
-	push af
-	ld a,00
-	adc a,a
-	call out_dgt
+	rlca
+	push	af
+	and	1
+	call	out_dgt
 	pop af
 	djnz l01c9h
 	ld a,'"'
@@ -369,7 +366,8 @@ out.ascii:
 	cp ' '
 	push af
 	call nc,outbl
-	call outquote
+	call	pstr_inl
+	dc	''''
 	pop af
 	jr nc,l0242h
 	sub 0c0h
@@ -381,7 +379,8 @@ l0242h:
 	call outchar
 	cp ''''
 	call z,outchar
-	call outquote
+	call	pstr_inl
+	dc	''''
 	sla c
 	pop bc
 	ret nc
@@ -396,14 +395,6 @@ outbl2:
 	call outbl
 outbl:
 	ld a,' '
-	jr outchar
-
-p_char_lparen:
-	ld a,'('
-	jr outchar
-
-outquote:
-	ld a,''''
 outchar:
 	push ix
 	push iy
@@ -425,22 +416,6 @@ outchar:
 	pop ix
 	ret
 
-pstr:
-	ld a,(hl)
-	inc hl
-	and a
-	ret z
-	call outchar
-	and a
-	ret m
-	jr pstr
-
-pstr_inl:
-	ex	(sp),hl
-	call	pstr
-	ex	(sp),hl
-	ret
-
 p_align_@_sym:
 	push	de
 	ld	de,(var.@)
@@ -460,7 +435,7 @@ p_goto_col:
 	call	outbl
 	jr	p_goto_col
 
-
+;-------------------------------------------------------------------------------
 
 inchar:
 	push ix
@@ -470,11 +445,11 @@ inchar:
 	ld c,BDOS_CSTAT
 	call ddtz_bdos
 	and a
-	jr z,l0284h
+	jr z,inch1
 	ld c,BDOS_CIN
 	call ddtz_bdos
 	scf
-l0284h:
+inch1:
 	pop bc
 	pop de
 	pop hl
@@ -498,6 +473,8 @@ get_line:
 	pop hl
 	ret
 
+;-------------------------------------------------------------------------------
+
 get_char_upper:
 	ld a,(de)
 toupper:
@@ -518,6 +495,8 @@ tolower:
 	or 020h
 	ret
 
+;-------------------------------------------------------------------------------
+
 skipbl0:
 	inc de
 skipbl:
@@ -527,12 +506,13 @@ skipbl:
 	or a
 	ret
 
+;-------------------------------------------------------------------------------
+
 next_arg:
 	call skipbl
 	cp ','
 	ret nz
-	inc de
-	call skipbl
+	call skipbl0
 	cp a
 	ret
 
@@ -542,18 +522,24 @@ assert_eol:
 to_error:
 	jp ERROR
 
+;-------------------------------------------------------------------------------
+
 chk_stack:
 	push hl
 	push de
 	ld hl,0
 	add hl,sp
-	ld de,stack-40
+	ld de,stack-(STACK_SIZE-28)
 	call cp_hl_de
 	pop de
 	pop hl
 	jr c,to_error
 	ret
 
+;-------------------------------------------------------------------------------
+
+add_hl_a2:
+	add a,a
 add_hl_a:
 	add a,l
 	ld l,a
@@ -572,12 +558,14 @@ sub_hl_a1:
 sub_hl_a:
 	push	bc
 	ld	c,a
-	ld	b,0
-	or	a
+	xor	a
+	ld	b,a
 	sbc	hl,bc
 	pop	bc
 	ret
 
+;-------------------------------------------------------------------------------
+
 sym_getname:
 	push	de
 	push	hl
@@ -644,6 +632,8 @@ pl_e:
 	pop	hl
 	ret
 
+;-------------------------------------------------------------------------------
+
 lookupch:
 	ld b,0
 l02f5h:
@@ -662,7 +652,7 @@ l0300h:
 	ret
 
 sub_0303h:
-	ld hl,b_0cc3_start
+	ld hl,t_reg_names
 	ld b,07fh
 	jr l030ch
 
@@ -681,7 +671,7 @@ l030ch:
 sub_0318h:
 	push bc
 	res 7,b
-	defb 03eh		;ld a,nn
+	defb 03eh		;ld a,nn: swallow push bc
 sub_031ch:
 	push bc
 	push de
@@ -703,22 +693,23 @@ l031eh:
 	pop bc
 	ret
 l0336h:
-	call sub_0345h
+	call str_sel_next
 l0339h:
 	pop de
 	and a
 	pop bc
 	ret
 
-sel_dc_string:
+str_sel:
 	inc b
-l033eh:
-	dec b
-	ret z
-	call sub_0345h
-	jr l033eh
+	jr str_sel2
+str_sel1:
+	call str_sel_next
+str_sel2:
+	djnz str_sel1
+	ret
 
-sub_0345h:
+str_sel_next:
 	ld a,(hl)
 	and a
 	ret z
@@ -729,12 +720,12 @@ l0348h:
 	ret m
 	jr l0348h
 
-sub_034eh:
+get_arg_range_target:
 	call get_arg_range
 	push hl
 	push bc
 	call next_arg
-	call sub_0363h
+	call get_arg_final
 	ex de,hl
 	pop bc
 	pop hl
@@ -745,7 +736,7 @@ sub_035dh:
 	jr c,error0
 	ret
 
-sub_0363h:
+get_arg_final:
 	call sub_035dh
 l0366h:
 	jp assert_eol
@@ -768,7 +759,7 @@ sub_0377h:
 	jr l0366h
 
 b_037c_start:
-	defb 0e6h
+	defb 0e6h		;and a,..  clear carry
 get_arg_range:
 	scf
 	ex af,af'
@@ -780,7 +771,7 @@ get_arg_range:
 	jr c,error0
 	ex af,af'
 	pop hl
-	defb 03eh
+	defb 03eh		;ld a,..  swallow pop af
 l038ch:
 	pop af
 	call get_range
@@ -826,6 +817,8 @@ l03b8h:
 	scf
 	ret
 
+;-------------------------------------------------------------------------------
+
 expr:
 	call skipbl
 expr1:
@@ -845,6 +838,8 @@ expr1:
 	pop de
 	ret
 
+;-------------------------------------------------------------------------------
+
 do_op_eq:
 	jr z,l03edh
 	jr l03ech
@@ -890,8 +885,7 @@ l0406h:
 l0411h:
 	ld hl,tab_func_eqlege
 	ld a,b
-	add a,a
-	call add_hl_a
+	call add_hl_a2
 	ld c,(hl)
 	inc hl
 	ld b,(hl)
@@ -983,40 +977,33 @@ doop_mod:
 ;     de: r  (x%y)
 
 div_hl_de:
-	push bc
-	ex de,hl
-	ld b,h
-	ld c,l
-	ld hl,0
-	ld a,16
+	push	bc
+	ex	de,hl		;de: x
+	ld	b,h		;bc: y
+	ld	c,l
+	ld	hl,0		;hl: r
+	ld	a,16
 
 ;  de: x   (x shifted out, q shifted in)
 ;  bc: y
 ;  hl: r   (initially 0)
 
-l047eh:
-	push af
-	add hl,hl
-	ex de,hl
-	xor a
-	add hl,hl
-	ex de,hl
-	adc a,l
-	sub c
-	ld l,a
-	ld a,h
-	sbc a,b
-	ld h,a
-	inc de
-	jr nc,l048fh
-	add hl,bc
-	dec de
-l048fh:
-	pop af
-	dec a
-	jr nz,l047eh
-	ex de,hl
-	pop bc
+div_lp:
+	ex	de,hl
+	add	hl,hl		;x <<= 1
+	ex	de,hl
+	adc	hl,hl		;r <<= 1
+	inc	de
+	or	a
+	sbc	hl,bc
+	jr 	nc,div_norestore
+	dec	de
+	add	hl,bc
+div_norestore:
+	dec	a
+	jr	nz,div_lp
+	ex	de,hl
+	pop	bc
 	ret
 
 doop_and:
@@ -1052,8 +1039,7 @@ do_binary_op:
 	call lookupch
 	ld a,b
 	ld hl,tblf_opa
-	add a,a
-	call add_hl_a
+	call add_hl_a2
 	ld c,(hl)
 	inc hl
 	ld b,(hl)
@@ -1074,6 +1060,8 @@ tblf_opa:
 	dw	doop_xor
 	dw	0
 
+;-------------------------------------------------------------------------------
+
 fact_factor:
 	call do_factor
 	ret nc
@@ -1085,6 +1073,7 @@ do_factor:
 	ret nc
 	inc de
 	ld hl,(BDOS+1)
+	dec hl
 	cp 'T'
 	ret z
 	ld hl,(high_load)
@@ -1127,14 +1116,15 @@ do_factor:
 	scf
 	ret
 
+;-------------------------------------------------------------------------------
+
 fact_reg.Y:
 	call get.decdigit
 	jr c,error1
 	inc de
 get_y_val:
-	add a,a
 	ld hl,reg_Y
-	call add_hl_a
+	call add_hl_a2
 	ld a,(hl)
 	inc hl
 	ld h,(hl)
@@ -1174,14 +1164,19 @@ fact_reg.CPU:
 	inc hl
 	ld h,(hl)
 	ld l,a
-	and a
+	xor a			;clr cy, a=0
 	bit 0,c
 	ret nz
-	ld h,000h
+	ld h,a
 	ret
 
+fact_factinv:
+	call fact_factor
+	jr cpl.hl
+
 fact_factneg:
 	call fact_factor
+neg.hl:
 	dec hl
 cpl.hl:
 	ld a,h
@@ -1192,10 +1187,6 @@ cpl.hl:
 	ld l,a
 	ret
 
-fact_factinv:
-	call fact_factor
-	jr cpl.hl
-
 fact_mem:
 	call expr1
 	jr c,error1
@@ -1243,12 +1234,17 @@ fs_nxtsym:
 	inc	b
 	push	hl			;symtbl ptr
 	push	de			;inpsym ptr
-fs_2:
+fs_nxtchar:
 	ld	a,(de)
 	djnz	fs_3
 	call	test_sym_char
 	jr	z,fs_cont
 	pop	hl			;inpsym ptr (discard)
+	inc	de
+	cp	a,':'
+	jr	z,fs_cont_1
+	dec	de
+
 	pop	hl			;symtbl ptr
 	inc	hl
 	ld	a,(hl)			;symval h
@@ -1258,20 +1254,24 @@ fs_2:
 	or	a			;clear carry
 	pop	bc
 	ret
+
 fs_3:
 	inc	de
 	dec	hl
 	xor	(hl)
 	and	c
-	jr	z,fs_2
+	jr	z,fs_nxtchar
 fs_cont:				;start over
 	pop	de			;inpsym ptr
+fs_cont_1:
 	pop	hl			;symtbl ptr
 	ld	a,(hl)
 	add	a,3
 	call	sub_hl_a
 	jr	fs_nxtsym
 
+;-------------------------------------------------------------------------------
+
 get.number:
 	call get.hexdigit
 	ret c
@@ -1315,7 +1315,7 @@ l05dbh:
 	jr next_bindigit
 l05e4h:
 	cp '"'
-	jp nz,ERROR
+	jr nz,error11
 	call get.bindigit
 	jr nc,l05dbh
 	or a
@@ -1340,11 +1340,12 @@ next_decdigit:
 decnum_done:
 	cp '.'
 	ret z
+error11:
 	jp ERROR
 
 sub_060ch:
 	call get_char_upper
-	cp '['
+	cp 'Z'+1
 	jr l0614h
 
 get.hexdigit:
@@ -1377,6 +1378,8 @@ l0625h:
 	sub '0'
 	ret
 
+;-------------------------------------------------------------------------------
+
 p_cpustat0:
 	call assert_eol
 p_cpustat:
@@ -1413,33 +1416,34 @@ p_f:
 	call p_flags
 	ld a,(reg.iff)
 	cp 0f3h
-	jp z,outbl
+	jr z,outbl_1
 	ld a,'E'
 	jp outchar
 p_f2:
 	ld a,(reg.f2)
 	call p_flags
-	jp outbl
+	jr outbl_1
 
 p_flags:
-	ld b,a
-	ld a,'S'
-	call sub_06aah
-	ld a,'Z'
-	call sub_06aah
-	rl b
-	ld a,'H'
-	call sub_06aah
-	rl b
-	ld a,'V'
-	call sub_06aah
-	ld a,'N'
-	call sub_06aah
-	ld a,'C'
-sub_06aah:
-	rl b
-	jp c,outchar
-	jp outbl
+	push	hl
+	ld	hl,t_flag_names+7
+	ld	c,a
+	ld	b,8
+fl_loop:
+	ld	a,' '
+	cp	(hl)
+	ld	a,c
+	rlca
+	ld	c,a
+	jr	z,fl_skip
+	ld	a,(hl)
+	call	c,outchar
+	call	nc,outbl
+fl_skip:
+	dec	hl
+	djnz	fl_loop
+	pop	hl
+	ret
 
 p_regs:
 	push de
@@ -1473,10 +1477,10 @@ l06deh:
 	ld a,(de)
 	call out_hex
 l06e2h:
-	call outbl
 	pop de
 	pop hl
-	ret
+outbl_1:
+	jp outbl
 
 b_06e9_start:
 	DC	'A '
@@ -1523,36 +1527,75 @@ b_0709_start:
 	db	000h
 	db	000h
 
+;-------------------------------------------------------------------------------
+; > G [startaddr] [;breakp..]
+;      Go [to start] [with temporary breakpoints]
+
 cmd_G:
 	sub a
 	ld (trace_call_flag),a
-	ld (l0941h),a
+	ld (bp_p_cpu_flag),a
 	call expr
 	jr c,l0740h
 	ld (reg.pc),hl
 l0740h:
 	call skipbl
-	jp z,user_go
+	jr z,user_go0
 	cp ';'
 	jp nz,ERROR
 	inc de
 	ld a,002h
 	call bp_enter
+user_go0:
 	jp user_go
 
+;-------------------------------------------------------------------------------
+
+bpl_init:
+	ld	b,BP_CNT
+	ld	ix,bp_tab
+	ex	(sp),hl
+	ld	(pbl_loop_adr),hl
+	ex	(sp),hl
+	ret
+
+bpl_next:
+	ld	de,BP_SIZE
+	push	af
+	add	ix,de
+	pop	af
+	dec	b
+	ret	z
+
+	ex	(sp),hl
+	ld	hl,(pbl_loop_adr)
+	ex	(sp),hl
+	ret
+
 bp_clr_temporary:
-	ld b,BP_CNT
-	ld ix,bp_tab
-l075ah:
+	call	bpl_init
+
 	ld a,(ix+000h)
 	and 0f1h
 	ld (ix+000h),a
 	call bp_clr_condition
-	ld de,BP_SIZE
-	add ix,de
-	djnz l075ah
+
+	call bpl_next
 	ret
 
+;-------------------------------------------------------------------------------
+; > B
+;      display all breakpoints
+; > B breakp [breakp..]
+;      set breakpoints
+; > BX
+;      clear all breakpoints
+; > BX address [address..]
+;      clear breakpoints
+;
+; where breakp is:
+;      [R] expression [I condition]
+
 cmd_B:
 	call skipbl
 	jr z,bp_print
@@ -1562,6 +1605,7 @@ cmd_B:
 	dec de
 	ld a,001h
 	jp bp_enter
+
 bp_clr0:
 	call skipbl
 	jr z,bp_clr_all
@@ -1577,9 +1621,8 @@ bp_clr_next:
 bp_clr_all:
 	scf
 bp_clr:
-	ld b,BP_CNT
-	ld ix,bp_tab
-l0799h:
+	call	bpl_init
+
 	push af
 	jr c,l07a7h
 	ld e,(ix+002h)
@@ -1590,16 +1633,13 @@ l07a7h:
 	ld (ix+000h),000h
 	call bp_clr_condition
 l07aeh:
-	ld de,BP_SIZE
-	add ix,de
 	pop af
-	djnz l0799h
+	call bpl_next
 	ret
 
 bp_print:
-	ld b,BP_CNT
-	ld ix,bp_tab
-bp_pr_l:
+	call	bpl_init
+
 	bit 0,(ix+000h)
 	jr z,bp_pr_cont
 	ld a,'R'
@@ -1633,11 +1673,10 @@ l07cdh:
 l0805h:
 	call crlf
 bp_pr_cont:
-	ld de,BP_SIZE
-	add ix,de
-	djnz bp_pr_l
+	call bpl_next
 	ret
 
+;-------------------------------------------------------------------------------
 ; Add break points to list
 ;   A = 1	 Permanent (B command)
 ;   A = 2	 Temporary (G command)
@@ -1653,7 +1692,7 @@ bp_enter:
 bp_e_1:
 	push bc
 	call expr
-	jp c,ERROR
+	jr c,error12
 	pop bc
 	bit 0,b
 	push bc
@@ -1678,17 +1717,14 @@ bp_e_1:
 	jr bp_enter
 
 bp_get_freeslot:
-	ld b,BP_CNT
-	ld ix,bp_tab
-bp_gf_l:
+	call	bpl_init
+
 	ld a,(ix+000h)
 	and 00fh
 	ret z
-	push bc
-	ld bc,BP_SIZE
-	add ix,bc
-	pop bc
-	djnz bp_gf_l
+
+	call	bpl_next
+error12
 	jp ERROR
 
 bp_get_count:
@@ -1698,7 +1734,7 @@ bp_get_count:
 	ret nz
 	inc de
 	call expr
-	jp c,ERROR
+	jr c,error12
 	ret
 
 bp_get_condition:
@@ -1710,7 +1746,7 @@ bp_get_condition:
 	call skipbl
 	push de
 	call expr
-	jp c,ERROR
+	jr c,error12
 	ex de,hl
 	pop de
 	push de
@@ -1722,20 +1758,21 @@ bp_get_condition:
 	add hl,bc
 	ld de,expr_bufe
 	call cp_hl_de
-	jp nc,ERROR
-	pop hl
-	ld (expr_p2),hl
-	pop de
-	ex de,hl
+	jr nc,error12
+	pop	de
+	pop	hl
+	push	de
 	ldir
-	xor a
-	ld (de),a
-	inc de
 	ex de,hl
+	ld (hl),c		; trailing 0
+	inc hl
 	ld (expr_p1),hl
-	ld hl,(expr_p2)
+	pop	hl
 	ret
 
+;-------------------------------------------------------------------------------
+; Breakpoint handling routine.
+
 bpddtz:
 	ld (reg.l),hl
 	pop hl
@@ -1749,13 +1786,13 @@ bpddtz:
 	push ix
 	push iy
 	ld a,i
-	call sub_0004h
+	call di_or_ei
 	ld h,a
 	ld l,000h
 	push hl
-	ld a,0f3h
+	ld a,0f3h		; EI
 	jp po,l08dfh
-	ld a,0fbh
+	ld a,0fbh		; DI
 l08dfh:
 	ld (reg.iff),a
 	ex af,af'
@@ -1764,18 +1801,18 @@ l08dfh:
 	push bc
 	push de
 	push hl
-	call sub_097ah
+	call bp_restore_mem
 	ld a,(b_21e2_start)
 	dec a
 	jr z,l090bh
-	call inchar
-	jr c,l0902h
+	call inchar		;Keyboard hit?
+	jr c,do_break		;yes
 	call sub_0913h
 	and a
 	jp z,user_go
 	and 083h
 	jp z,l2151h
-l0902h:
+do_break:
 	call bp_clr_temporary
 	call p_cpustat
 	jp mainloop
@@ -1789,10 +1826,9 @@ sub_0913h:
 	ld a,080h
 	ex af,af'
 	sub a
-	ld (l0941h),a
-	ld b,BP_CNT
-	ld ix,bp_tab
-l0920h:
+	ld (bp_p_cpu_flag),a
+	call	bpl_init
+
 	ld a,(ix+000h)
 	and 007h
 	jr z,l0938h
@@ -1804,9 +1840,8 @@ l0920h:
 	call z,sub_0942h
 	pop bc
 l0938h:
-	ld de,BP_SIZE
-	add ix,de
-	djnz l0920h
+
+	call	bpl_next
 	ex af,af'
 	ret
 
@@ -1835,7 +1870,7 @@ l0969h:
 	bit 4,(ix+000h)
 	ret z
 	ld a,001h
-	ld (l0941h),a
+	ld (bp_p_cpu_flag),a
 	ret
 l0974h:
 	ex af,af'
@@ -1843,10 +1878,9 @@ l0974h:
 	ex af,af'
 	ret
 
-sub_097ah:
-	ld b,BP_CNT
-	ld ix,bp_tab
-l0980h:
+bp_restore_mem:
+	call	bpl_init
+
 	bit 5,(ix+000h)
 	res 5,(ix+000h)
 	jr z,l099ah
@@ -1859,32 +1893,28 @@ l0980h:
 	ld (hl),a
 l099ah:
 	res 3,(ix+000h)
-	ld de,BP_SIZE
-	add ix,de
-	djnz l0980h
+
+	call	bpl_next
 	ret
 
-sub_09a6h:
-	ld b,BP_CNT
-	ld ix,bp_tab
-l09ach:
+bp_tst_@pc:
+	call	bpl_init
+
 	ld a,(ix+000h)
-	and 003h
-	jr z,l09c0h
+	and 003h		;User bp (temporary or permanent)?
+	jr z,bp_tst_e		;No, check next
 	ld e,(ix+002h)
 	ld d,(ix+003h)
 	ld hl,(reg.pc)
-	call cp_hl_de
-	ret z
-l09c0h:
-	ld de,BP_SIZE
-	add ix,de
-	djnz l09ach
+	call cp_hl_de		;Current PC is on a User bp
+	ret z			;Return zero
+bp_tst_e:
+	call	bpl_next
 	sub a
-	inc a
-	ret
+	inc a			;Not on a user bp
+	ret			;Return not zero
 
-sub_09cah:
+bp_trace_enter:
 	call bp_get_freeslot
 	ld (ix+004h),001h
 	ld (ix+005h),000h
@@ -1895,16 +1925,15 @@ sub_09cah:
 	ld a,(b_21e2_start)
 	and a
 	ld a,008h
-	jr nz,l09edh
+	jr nz,bp_t_e
 	rra
-l09edh:
+bp_t_e:
 	ld (ix+000h),a
 	ret
 
 bp_set_to_mem:
-	ld b,BP_CNT
-	ld ix,bp_tab
-l09f7h:
+	call	bpl_init
+
 	ld a,(ix+000h)
 	and c
 	jr z,l0a1dh
@@ -1925,23 +1954,23 @@ l09f7h:
 	inc hl
 	ld (hl),d
 l0a1dh:
-	ld de,BP_SIZE
-	add ix,de
-	djnz l09f7h
+	call	bpl_next
 	ret
 
+;-------------------------------------------------------------------------------
+
 user_go:
 	sub a
 	ld (b_21e2_start),a
-	ld a,(l0941h)
+	ld a,(bp_p_cpu_flag)
 	and a
 	call nz,p_cpustat
-	call sub_09a6h
+	call bp_tst_@pc
 	ld c,007h
 	jr nz,l0a41h
 	ld a,001h
 	ld (b_21e2_start),a
-	call sub_1ffeh
+	call tc_set_bp
 	ld c,008h
 l0a41h:
 	call bp_set_to_mem
@@ -1963,15 +1992,17 @@ l0a41h:
 	ld sp,(reg_sp)
 	jp reg.iff
 
+;-------------------------------------------------------------------------------
+
 bp_clr_condition:
 	ld a,(ix+000h)
 	and 003h
-	ret nz
+	ret nz				; No (user) bp set
 	ld e,(ix+006h)
 	ld d,(ix+007h)
 	ld a,d
 	or e
-	ret z
+	ret z				; No conditional expression
 	push bc
 	ld h,d
 	ld l,e
@@ -2015,6 +2046,12 @@ l0ab0h:
 	ld (iy+007h),d
 	ret
 
+;-------------------------------------------------------------------------------
+; > Y
+;      examine all Y variables
+; > Y[0..9]
+;      examine (and substitute) an Y variable
+
 cmd_Y:
 	call get.decdigit
 	jr c,l0bc3h
@@ -2061,7 +2098,15 @@ sub_0bdch:
 	add hl,bc
 	ex de,hl
 	ld c,003h
-	jp l0c33h
+	jr l0c33h
+
+;-------------------------------------------------------------------------------
+; > X
+;      eXamine (display) all cpu registers and
+;      the instruction at the current program counter
+; > X register
+;      eXamine (and substitute) a register
+
 
 cmd_X:
 	call skipbl
@@ -2069,15 +2114,15 @@ cmd_X:
 	jp nc,p_cpustat0
 	call assert_eol
 	ld a,b
-	cp 01eh
+	cp 30
 	jr z,l0c5fh
-	cp 01fh
+	cp 31
 	jr z,l0c4fh
-	cp 01dh
+	cp 29
 	jp z,ERROR
 	ex de,hl
-	ld hl,b_0cc3_start
-	call sel_dc_string
+	ld hl,t_reg_names
+	call str_sel
 l0c12h:
 	call l0c33h
 l0c15h:
@@ -2087,7 +2132,7 @@ l0c15h:
 	call get_line
 	call skipbl
 	jr z,l0c30h
-	call sub_0363h
+	call get_arg_final
 	ex de,hl
 	pop bc
 	pop hl
@@ -2135,43 +2180,41 @@ l0c5fh:
 
 sub_0c6ah:
 	push af
-	ld b,000h
 	call outbl
 	call assert_eol
 	call get_line
 	pop af
 	ex af,af'
+	ld b,0
 l0c76h:
 	call skipbl
 	ld a,b
 	ret z
 	push bc
-	ld hl,b_0ca4_start
+	ld hl,t_flag_names
 	call lookupch
 	jp nc,ERROR
-	ld a,b
-	cp 008h
-	jr z,l0c97h
-	pop bc
-	rlca
-	rlca
-	rlca
-	add a,0c0h
-	ld (l0c94h),a
-	defb 0cbh
-l0c94h:
-	defb 0c0h
+	inc	b
+	xor	a
+	scf
+nxt_f:
+	rla
+	djnz	nxt_f
+	pop	bc
+	jr	c,l0c97h
+	or	b
+	ld	b,a
 	jr l0c76h
+
 l0c97h:
 	ex af,af'
 	jp nc,ERROR
 	ex af,af'
 	ld a,0fbh
 	ld (reg.iff),a
-	pop bc
 	jr l0c76h
 
-b_0ca4_start:
+t_flag_names:
 	db	'CNV H ZSE',0
 
 sub_0caeh:
@@ -2191,39 +2234,39 @@ sub_0caeh:
 	scf
 	ret
 
-b_0cc3_start:
-	DC	'BC'''
-	DC	'DE'''
-	DC	'HL'''
-	DC	'BC'
-	DC	'DE'
-	DC	'HL'
-	DC	'A'''
-	DC	'B'''
-	DC	'C'''
-	DC	'D'''
-	DC	'E'''
-	DC	'H'''
-	DC	'L'''
-	DC	'A'
-	DC	'B'
-	DC	'C'
-	DC	'D'
-	DC	'E'
-	DC	'H'
-	DC	'L'
-	DC	'IX'
-	DC	'IY'
-	DC	'SP'
-	DC	'PC'
-	DC	'X'
-	DC	'Y'
-	DC	'S'
-	DC	'P'
-	DC	'I'
-	DC	'IP'
-	DC	'F'''
-	DC	'F'
+t_reg_names:
+	DC	'BC'''		;0
+	DC	'DE'''		;1
+	DC	'HL'''		;2
+	DC	'BC'		;3
+	DC	'DE'		;4
+	DC	'HL'		;5
+	DC	'A'''		;6
+	DC	'B'''		;7
+	DC	'C'''		;8
+	DC	'D'''		;9
+	DC	'E'''		;10
+	DC	'H'''		;11
+	DC	'L'''		;12
+	DC	'A'		;13
+	DC	'B'		;14
+	DC	'C'		;15
+	DC	'D'		;16
+	DC	'E'		;17
+	DC	'H'		;18
+	DC	'L'		;19
+	DC	'IX'		;20
+	DC	'IY'		;21
+	DC	'SP'		;22
+	DC	'PC'		;23
+	DC	'X'		;24
+	DC	'Y'		;25
+	DC	'S'		;26
+	DC	'P'		;27
+	DC	'I'		;28
+	DC	'IP'		;29
+	DC	'F'''		;30
+	DC	'F'		;31
 	DB	0
 
 b_0cfa_start:
@@ -2292,6 +2335,10 @@ b_0cfa_start:
 	db	000h
 	dw	reg.f
 
+;-------------------------------------------------------------------------------
+; > S [startaddr]
+;      Substitute memory
+
 cmd_S:
 	ld hl,(last_S)
 	call get_lastarg_def
@@ -2328,6 +2375,10 @@ l0d8ah:
 	call sub_0ef8h
 	jr l0d60h
 
+;-------------------------------------------------------------------------------
+; > @
+;      examine (substitute) displacement register @
+
 cmd_@:
 	call assert_eol
 	ld hl,msg_@
@@ -2338,8 +2389,11 @@ cmd_@:
 msg_@:
 	dc	'@'
 
+;-------------------------------------------------------------------------------
+; >>I [port]
+;      Input a byte from port
+
 cmd_I:
-	ld hl,cmd_I
 	ld (cmd_rpt),hl
 	ld hl,(last_I)
 	call get_lastarg_def
@@ -2354,8 +2408,11 @@ cmd_I:
 	call out.bin.b
 	jp crlf
 
+;-------------------------------------------------------------------------------
+; >>O [byte] [port]
+;      Output a byte to a port
+
 cmd_O:
-	ld hl,cmd_O
 	ld (cmd_rpt),hl
 	ld hl,(last_O_val)
 	call get_arg_def
@@ -2372,8 +2429,12 @@ cmd_O:
 	out (c),a
 	ret
 
+;-------------------------------------------------------------------------------
+; > Vstartaddr endaddr targetaddr
+;      Verify (compare) two memory areas
+
 cmd_V:
-	call sub_034eh
+	call get_arg_range_target
 l0dedh:
 	push bc
 	ld a,(de)
@@ -2395,14 +2456,15 @@ l0dedh:
 	call crlf
 l0e10h:
 	pop bc
-	inc hl
 	inc de
-	dec bc
-	ld a,b
-	or c
-	jr nz,l0dedh
+	cpi
+	jp pe,l0dedh
 	ret
 
+;-------------------------------------------------------------------------------
+; > M[V] startaddr endaddr destaddr
+;      Move memory [and verify]
+
 cmd_M:
 	call get_char_upper
 	cp 'V'
@@ -2410,7 +2472,7 @@ cmd_M:
 	inc de
 l0e1fh:
 	push af
-	call sub_034eh
+	call get_arg_range_target
 	push hl
 	push de
 	push bc
@@ -2433,6 +2495,17 @@ cmdm_up:
 	jr z,l0dedh
 	ret
 
+;-------------------------------------------------------------------------------
+; > H
+;      display Highest load address of last filed loaded, Maximum "High"
+;      off all loaded files, and Top address of available memory
+; > HS
+;      display symbol list
+; > H expression
+;      evaluate expression and display result in hex, decimal and other formats
+; > H expression expression
+;      display sum und difference of expressions
+
 cmd_H:
 	call get_char_upper
 	cp 'S'
@@ -2517,6 +2590,10 @@ psym_e:
 	jp	crlf
 
 
+;-------------------------------------------------------------------------------
+; > Q[J] startaddr endaddr bytes
+;      Query memory for a byte string [Justified]
+
 cmd_Q:
 	call get_char_upper
 	sub 'J'
@@ -2541,7 +2618,7 @@ l0e96h:
 	add hl,bc
 l0ea7h:
 	ld bc,16
-	and a
+	and a			;clear carry
 	call sub_0f58h
 	pop hl
 	pop bc
@@ -2556,6 +2633,10 @@ l0eb0h:
 	pop bc
 	ret
 
+;-------------------------------------------------------------------------------
+; > Z startaddr endaddr bytes
+;      Zap (fill) memory with a byte string
+
 cmd_Z:
 	call get_arg_range
 	push bc
@@ -2583,7 +2664,7 @@ sub_0ed7h:
 	push	de
 	push bc
 l0edah:
-	call get_char_upper
+	ld a,(de)
 	cp (hl)
 	jr nz,l0ee2h
 	inc de
@@ -2605,9 +2686,9 @@ sub_0ee6h:
 	ret nz
 	jp ERROR
 
-sub_0ef7h:
+sub_0ef7h:			;from cmd_Q, cmd_Z
 	db	0e6h		; and 037h (clear carry)
-sub_0ef8h:
+sub_0ef8h:			;from cmd_S
 	scf
 l0ef9h:
 	push af
@@ -2669,8 +2750,11 @@ l0f42h:
 	ld (last_S),hl
 	ret
 
+;-------------------------------------------------------------------------------
+; >>D [startaddr] [endaddr]
+;      Display memory in hex and ASCII
+
 cmd_D:
-	ld hl,cmd_D
 	ld (cmd_rpt),hl
 	ld hl,(last_D)
 	ld bc,128
@@ -2737,6 +2821,10 @@ l0fach:
 	ld a,'.'
 	ret
 
+;-------------------------------------------------------------------------------
+; > Fcommandline
+;      specifiy filenames and command line
+
 cmd_F:
 	push de
 	ld hl,DMA_BUF+1
@@ -2834,6 +2922,7 @@ sub_1012h:
 	cp '.'
 	ret z
 	ld c,'?'
+	call toupper
 	cp '*'
 	ret
 
@@ -2865,6 +2954,8 @@ sub_1043h:
 	cp ','
 	ret
 
+;-------------------------------------------------------------------------------
+
 setup_fcb:
 	push de
 	ld hl,12
@@ -2881,6 +2972,8 @@ l1052h:
 	pop de
 	ret
 
+;-------------------------------------------------------------------------------
+
 file_open:
 	ld (cur_fcb),de
 	call setup_fcb
@@ -3004,6 +3097,10 @@ read_hexbyte0:
 	pop	bc
 	ret
 
+;-------------------------------------------------------------------------------
+; > R [displacement]
+;      Read a binary or hex file and or symbol file [add displacement]
+
 cmd_R:
 	ld hl,0
 	call get_lastarg_def
@@ -3206,18 +3303,21 @@ test_sym_char:
 ; return nc if valid alfanumeric char
 
 test_alphanum:
-	cp	'z'+1
+	cp	'z'
+	ret	z
 	ccf
 	ret	c
 	cp	'a'
 	ret	nc
-	cp	'Z'+1
+	cp	'Z'
+	ret	z
 	ccf
 	ret	c
 	cp	'?'
 	ret	nc
 test_numeral:
-	cp	'9'+1
+	cp	'9'
+	ret	z
 	ccf
 	ret	c
 	cp	'0'
@@ -3234,6 +3334,8 @@ test_whitespace:
 	cp	TAB
 	ret
 
+;-------------------------------------------------------------------------------
+
 p_max_high0:
 	call assert_eol
 p_max_high:
@@ -3248,9 +3350,14 @@ p_max_high:
 	call pstr_inl
 	DC	'  Top = '
 	ld hl,(BDOS+1)
+	dec hl
 	call out_hl
 	jp crlf
 
+;-------------------------------------------------------------------------------
+; > Wstartaddr endaddr
+;      Write a file to disk
+
 cmd_W:
 	call get_arg_range
 	call assert_eol
@@ -3312,6 +3419,10 @@ close_file:
 	ld c,BDOS_CLOSE
 	jp ddtz_bdos
 
+;-------------------------------------------------------------------------------
+; > A [startaddr]
+;      Assemble Zilog Z180 mnemonics
+
 cmd_A:
 	ld hl,(last_A)
 	call get_lastarg_def
@@ -3354,7 +3465,7 @@ cmda_lpend:
 	jr cmda_loop
 
 cmda_restart:
-	call l0146h
+	call p_msg_error
 	ld sp,(l1262h)
 	jr cmda_loop
 
@@ -3381,6 +3492,8 @@ asemble_line:
 CALL_HL:
 	jp (hl)
 
+;-------------------------------------------------------------------------------
+
 b_1289_start:
 	dw	as.ADC_SBC		;ADC
 	db	088h			;
@@ -3538,6 +3651,8 @@ b_1289_start:
 	dw	as.TSTIO		;TSTIO
 	db	074h       		;
 
+;-------------------------------------------------------------------------------
+
 as.TST:
 	call arg.r_HL_A		;
 	jr nc,as.tst_0
@@ -3628,7 +3743,7 @@ as.LD:
 l1395h:
 	call assert_eol
 	ld a,(prefix_ixiy)
-l139bh:
+as_store_4:
 	ld (iy+000h),a
 	ld (iy+001h),b
 	ld (iy+002h),l
@@ -3643,7 +3758,7 @@ l13aah:
 	inc de
 	ld b,032h
 
-as.store_3:
+as_store_3:
 	call assert_eol
 	ld (iy+000h),b
 	ld (iy+001h),l
@@ -3659,10 +3774,10 @@ l13c2h:
 l13c9h:
 	call assert_eol
 	ld a,0edh
-	jr l139bh
+	jr as_store_4
 l13d0h:
 	ld b,022h
-	jr as.store_3
+	jr as_store_3
 
 l13d4h:
 	ld b,a
@@ -3736,7 +3851,7 @@ l1432h:
 	add a,006h
 l143fh:
 	ld b,a
-as.store_2:
+as_store_2:
 	call assert_eol
 	ld (iy+000h),b
 	ld (iy+001h),l
@@ -3763,7 +3878,7 @@ l1466h:
 	call test_expr
 	call test_paren_close
 	ld b,03ah
-	jp as.store_3
+	jp as_store_3
 
 l1471h:
 	call assert_comma
@@ -3827,7 +3942,7 @@ l14cch:
 
 l14e3h:
 	ld b,02ah
-	jp as.store_3
+	jp as_store_3
 
 l14e8h:
 	call test_expr
@@ -3835,7 +3950,7 @@ l14e8h:
 	ld a,001h
 	add a,b
 	ld b,a
-	jp as.store_3
+	jp as_store_3
 l14f5h:
 	call assert_comma
 	call get_char_upper
@@ -4037,7 +4152,7 @@ l163ch:
 l163eh:
 	pop af
 	call test_expr
-	jp as.store_3
+	jp as_store_3
 
 as.RET:
 	call arg.cc_ZCPS
@@ -4070,7 +4185,7 @@ l1666h:
 	pop af
 l166eh:
 	call test_expr
-	jp as.store_3
+	jp as_store_3
 l1674h:
 	call assert_eol
 	ld a,b
@@ -4085,7 +4200,7 @@ l1680h:
 	ld b,0fdh
 l1687h:
 	ld l,0e9h
-	jp as.store_2
+	jp as_store_2
 
 l168ch:
 	DC	'(HL)'
@@ -4108,7 +4223,7 @@ l16a9h:
 	call assert_comma
 l16aeh:
 	call arg.j_displ
-	jp as.store_2
+	jp as_store_2
 
 as.IM:
 	call arg.imm_8bit
@@ -4164,7 +4279,7 @@ as.IN:
 	jr c,l1715h
 	call arg.addr_8bit
 	ld b,0dbh
-	jp as.store_2
+	jp as_store_2
 l170fh:
 	call assert_comma
 	call sub_171bh
@@ -4198,7 +4313,7 @@ l1739h:
 	jr nz,error7
 	inc de
 	ld b,0d3h
-	jp as.store_2
+	jp as_store_2
 
 as.EX:
 	ld hl,b_176d_start
@@ -4326,7 +4441,7 @@ error8:
 
 arg.zz:
 	push hl
-	ld hl,t_BC.DE.HL.AF
+	ld hl,t_arg_rp2
 	jr l181fh
 
 arg.reg_16bit:
@@ -4335,7 +4450,7 @@ arg.reg_16bit:
 
 arg.ww:
 	push hl
-	ld hl,t_BC.DE.HL.SP
+	ld hl,t_arg_rp
 l181fh:
 	push bc
 	call sub_030ah
@@ -4355,7 +4470,7 @@ arg.r_HL_A:
 	call skipbl
 	push bc
 	push hl
-	ld hl,t_BCDEHL_HL_A
+	ld hl,t_arg_r
 	call sub_030ah
 	ld a,b
 	pop hl
@@ -4443,7 +4558,7 @@ arg.cc_ZCPS:
 	jr l18b1h
 
 arg.cc_ZC:
-	ld hl,t_tstfl_ZC
+	ld hl,t_arg_cc
 	ld c,003h
 l18b1h:
 	push bc
@@ -4471,8 +4586,11 @@ test_paren_close:
 	inc de
 	ret
 
+;-------------------------------------------------------------------------------
+; >>L [startaddr] [endaddr]
+;      List disassembled code
+
 cmd_L:
-	ld hl,cmd_L
 	ld (cmd_rpt),hl
 	call expr
 	jr nc,l18dbh
@@ -4504,6 +4622,8 @@ l190fh:
 	jr	c,l190fh
 	ret
 
+;-------------------------------------------------------------------------------
+
 cmdl_p_line:
 	push	hl
 	call	p_disas_line
@@ -4534,6 +4654,8 @@ p_disas_line:
 	call	outbl
 	jp	p_symbol
 
+;-------------------------------------------------------------------------------
+
 p_offset:
 	ld de,(var.@)
 	ld a,d
@@ -4547,6 +4669,8 @@ p_offset:
 	add	hl,de
 	jp out_rparen
 
+;-------------------------------------------------------------------------------
+
 p_disas_instr:
 	sub a
 	ld (disas_argtype),a
@@ -4556,10 +4680,10 @@ p_disas_instr:
 	ld	a,(con_col)
 	add	a,5
 	ld	c,a
-	call	pstr
+	call	pstr					;print mnemonic
 	call	p_goto_col
 	ex de,hl
-	call call_hl
+	call call_hl					;print arguments
 	pop bc
 	ld a,(disas_argtype)
 	ld hl,(disas_arg_16)
@@ -4606,6 +4730,67 @@ l19b1h:
 	scf
 	ret
 
+;-------------------------------------------------------------------------------
+
+disas_nopfx:
+	ld hl,b_1b54_start		;2 byte opcodes
+	call lookup_op
+	ld b,2
+	ret c
+	ld hl,b_1ab6_start		;1 byte opcodes (no parameters)
+	call sub_1a72h
+	ld b,1
+	ret c
+	ld hl,b_1ad1_start		;1 byte opcodes
+	call lookup_op
+	ld b,1
+	ret c
+	ld hl,b_1b9b_start		;3 byte opcodes
+	call lookup_op
+	ret nc
+	ld b,3
+	ret
+
+;-------------------------------------------------------------------------------
+
+disas_pfx.ED:
+	inc iy
+	ld hl,b_1bc9_start		;1 byte opcode, no arguments
+	call sub_1a72h
+	ld b,2
+	ret c
+	ld hl,b_1bf4_start
+	call lookup_op
+	ld b,2
+	ret c
+
+	ld hl,l228bh
+	call lookup_op
+	ld b,3
+	ret c
+	ld hl,b_1c40_start
+	call lookup_op
+	ld b,4
+	ret
+
+;-------------------------------------------------------------------------------
+
+disas_pfx.CB:
+	push iy
+	inc iy
+	ld a,(isprefix_ixiy)
+	and a
+	jr z,l1a42h
+	inc iy
+l1a42h:
+	ld hl,b_1c55_start
+	call lookup_op
+	pop iy
+	ld b,2
+	ret
+
+;-------------------------------------------------------------------------------
+
 disas_pfx.DDFD:
 	inc iy
 	ld hl,b_19ef_start
@@ -4632,6 +4817,7 @@ l19edh:
 	and a
 	ret
 
+;-------------------------------------------------------------------------------
 ; DD/FD 3 byte (ix+d)/(iy+d)
 b_19ef_start:
 	db	034h
@@ -4679,58 +4865,7 @@ l1a0ah:
 	db	0f9h
 	db	0
 
-disas_pfx.ED:
-	inc iy
-	ld hl,b_1bc9_start
-	call sub_1a72h
-	ld b,2
-	ret c
-	ld hl,b_1bf4_start
-	call lookup_opc
-	ld b,2
-	ret c
-
-	ld hl,l228bh
-	call lookup_opc
-	ld b,3
-	ret c
-	ld hl,b_1c40_start
-	call lookup_opc
-	ld b,4
-	ret
-
-disas_pfx.CB:
-	push iy
-	inc iy
-	ld a,(isprefix_ixiy)
-	and a
-	jr z,l1a42h
-	inc iy
-l1a42h:
-	ld hl,b_1c55_start
-	call lookup_opc
-	pop iy
-	ld b,2
-	ret
-
-disas_nopfx:
-	ld hl,b_1b54_start
-	call lookup_opc
-	ld b,2
-	ret c
-	ld hl,b_1ab6_start
-	call sub_1a72h
-	ld b,1
-	ret c
-	ld hl,b_1ad1_start
-	call lookup_opc
-	ld b,1
-	ret c
-	ld hl,b_1b9b_start
-	call lookup_opc
-	ret nc
-	ld b,3
-	ret
+;-------------------------------------------------------------------------------
 
 sub_1a72h:
 	ld a,(hl)
@@ -4758,7 +4893,7 @@ test_DDFD:
 	scf
 	ret
 
-lookup_opc:
+lookup_op:
 	ld a,(iy+000h)
 	and (hl)
 	inc hl
@@ -4770,7 +4905,7 @@ lookup_opc:
 	inc hl
 	ld a,(hl)
 	and a
-	jr nz,lookup_opc
+	jr nz,lookup_op
 	ret
 
 l1aa8h:
@@ -4787,6 +4922,7 @@ get_mnemonic:
 	scf
 	ret
 
+;-------------------------------------------------------------------------------
 ; 1 byte opcodes (no parameters)
 ; Format: db opcode, t_MNEMONICS-index
 b_1ab6_start:
@@ -4864,7 +5000,7 @@ b_1ad1_start:
 	dw l1ce5h
 	db 0
 
-; 2 byte opdodes
+; 2 byte opcodes
 b_1b54_start:
 	db 0c7h,006h,056h	;ld r,nn
 	dw l1cfah
@@ -5040,6 +5176,8 @@ b_1c55_start:
 	dw p_arg_bitop
 	db 0
 
+;-------------------------------------------------------------------------------
+
 p_arg_r_r:
 	call p_arg_r
 	call p_char_comma
@@ -5102,8 +5240,7 @@ l1ce5h:
 sub_1ce8h:
 	call p_char_lparen
 	call p_arg_ww
-out_rparen:
-	jp p_char_rparen
+	jr out_rparen
 
 l1cf5h:
 	call p_A_comma
@@ -5143,7 +5280,11 @@ l1d29h:
 sub_1d2ch:
 	call p_char_lparen
 	ld a,(iy+001h)
-	jp l1e6bh
+p_arg_nn_rp:
+	call out_hex
+out_rparen:
+	jr p_char_rparen
+
 l1d37h:
 	call sub_1d2ch
 	jr p_char_comma_A
@@ -5180,27 +5321,30 @@ p_arg_addr_a:
 	call p_arg_addr
 p_char_comma_A:
 	call p_char_comma
+	jr p_char_A
+
+p_A_comma:
+	call p_char_A
+p_char_comma:
+	ld a,','
+	db 021h
 p_char_A:
 	ld a,'A'
-	jr outchar1
-p_arg_a_addr:
-	call p_A_comma
-	jp p_arg_addr
+	db 021h
 l1d85h:
 	ld a,'0'
-	jr outchar1
+	db 021h
 l1d89h:
 	ld a,'1'
-	jr outchar1
+	db 021h
 l1d8dh:
 	ld a,'2'
-	jr outchar1
-
-p_A_comma:
-	call p_char_A
-p_char_comma:
-	ld a,','
-outchar1:
+	db 021h
+p_char_rparen:
+	ld a,')'
+	db 021h
+p_char_lparen:
+	ld a,'('
 	jp outchar
 
 l1d92h:
@@ -5253,6 +5397,16 @@ p_arg_ww_addr:
 	call p_char_comma
 	jr p_arg_addr
 
+p_arg_a_addr:
+	call p_A_comma
+p_arg_addr:
+	call p_char_lparen
+	ld l,(iy+001h)
+	ld h,(iy+002h)
+	ld a,001h
+	call sub_1d50h
+	jr p_char_rparen
+
 p_arg_bitop:
 	ld a,(isprefix_ixiy)
 	and a
@@ -5284,17 +5438,6 @@ l1e0eh:
 l1e11h:
 	jr p_arg_r0
 
-p_arg_addr:
-	call p_char_lparen
-	ld l,(iy+001h)
-	ld h,(iy+002h)
-	ld a,001h
-	call sub_1d50h
-
-p_char_rparen:
-	ld a,')'
-	jp outchar
-
 p_arg_r:
 	ld a,(iy+000h)
 	rra
@@ -5319,23 +5462,21 @@ p_arg_r0:
 l1e4dh:
 	call pstr
 	ld a,(iy+001h)
-	and a
-	jp m,l1e61h
-	call	pstr_inl
-	dc	'+'
-	ld a,(iy+001h)
-	jr l1e6bh
-l1e61h:
-	call	pstr_inl
-	dc	'-'
-	ld a,(iy+001h)
+	push af
+	rlca
+	ld a,'+'
+	jr nc,l1e61h
+	pop af
 	neg
-l1e6bh:
-	call out_hex
-	jr p_char_rparen
+	push af
+	ld a,'-'
+l1e61h:
+	call outchar
+	pop af
+	jp p_arg_nn_rp
 
 p_arg_r1:
-	ld hl,t_BCDEHL_HL_A
+	ld hl,t_arg_r
 	jr p_arg
 
 b_1e78_start:
@@ -5348,10 +5489,10 @@ p_arg_hlixiy:
 	ld hl,t_HL.IX.IY
 	jr p_arg
 p_arg_zz:
-	ld hl,t_BC.DE.HL.AF
+	ld hl,t_arg_rp2
 	jr l1e8eh
 p_arg_ww:
-	ld hl,t_BC.DE.HL.SP
+	ld hl,t_arg_rp
 l1e8eh:
 	ld a,(iy+000h)
 	rra
@@ -5373,8 +5514,26 @@ p_arg_cc0:
 	ld hl,t_tstfl_ZCPS
 p_arg:
 	ld b,a
-	call sel_dc_string
-	jp pstr
+	;fall thru
+pstr_sel:
+	call str_sel
+	;fall thru
+pstr:
+	ld a,(hl)
+	inc hl
+	and a
+	ret z
+	call outchar
+	ret m
+	jr pstr
+
+pstr_inl:
+	ex	(sp),hl
+	call	pstr
+	ex	(sp),hl
+	ret
+
+;-------------------------------------------------------------------------------
 
 t_MNEMONICS:
 	DC	'ADC'
@@ -5456,7 +5615,7 @@ t_MNEMONICS:
 	DC	'TSTIO'
 	DB	0
 
-t_BCDEHL_HL_A:
+t_arg_r:
 	DC	'B'
 	DC	'C'
 	DC	'D'
@@ -5466,13 +5625,13 @@ t_BCDEHL_HL_A:
 	DC	'(HL)'
 	DC	'A'
 	DB	0
-t_BC.DE.HL.SP:
+t_arg_rp:
 	DC	'BC'
 	DC	'DE'
 	DC	'HL'
 	DC	'SP'
 	DB	0
-t_BC.DE.HL.AF:
+t_arg_rp2:
 	DC	'BC'
 	DC	'DE'
 t_HL.AF:
@@ -5497,7 +5656,7 @@ t_IX.IY:
 	DC	'IX'
 	DC	'IY'
 	DB	0
-t_tstfl_ZC:
+t_arg_cc:
 	DC	'NZ'
 	DC	'Z'
 	DC	'NC'
@@ -5527,7 +5686,9 @@ t__C_:
 	DC	'(C)'
 	DB	0
 
-sub_1ffeh:
+;-------------------------------------------------------------------------------
+
+tc_set_bp:
 	ld hl,(reg.pc)
 	ld a,h
 	or l
@@ -5535,7 +5696,7 @@ sub_1ffeh:
 	ld de,BDOS
 	and a
 	sbc hl,de
-	ld hl,l20edh
+	ld hl,l20edh		;set break after BDOS call
 	jr z,l2031h
 	ld iy,(reg.pc)
 	call disas_get_instrlen
@@ -5544,20 +5705,22 @@ sub_1ffeh:
 	ld b,0
 	ld hl,(reg.pc)
 	add hl,bc
-	call sub_09cah
+	call bp_trace_enter
 	ld iy,(reg.pc)
 	ld hl,b_2039_start
-	call lookup_opc
+	call lookup_op
 	ccf
 	ret c
 	ex de,hl
 l2031h:
 	call CALL_HL
-	call c,sub_09cah
+	call c,bp_trace_enter
 l2037h:
 	scf
 	ret
 
+;-------------------------------------------------------------------------------
+
 b_2039_start:
 	db 0ffh,0ddh,000h	;Prefix DD
 	dw l20a7h
@@ -5577,20 +5740,22 @@ b_2048_start:
 	dw l20dch
 	db 0ffh,0cfh,000h	;rst 8
 	dw l2115h
-	db 0c7h,0c7h,000h	;
+	db 0c7h,0c7h,000h	;rst n
 	dw l20f9h
-	db 0c7h,0c4h,000h	;
+	db 0c7h,0c4h,000h	;call cc,mn
 	dw l2080h
-	db 0f7h,010h,000h	;
+	db 0f7h,010h,000h	;djnz d; jr d
 	dw l2093h
-	db 0e7h,020h,000h	;
+	db 0e7h,020h,000h	;jr cc,d
 	dw l2093h
-	db 0c7h,0c2h,000h	;
+	db 0c7h,0c2h,000h	;jp cc,mn
 	dw l208bh
-	db 0c7h,0c0h,000h	;
+	db 0c7h,0c0h,000h	;ret cc
 	dw l20c5h
 	db 0
 
+;-------------------------------------------------------------------------------
+; call mn	call cc,mn
 l2080h:
 	ld a,(b_21e2_start)
 	and a
@@ -5598,11 +5763,15 @@ l2080h:
 	ld a,(trace_call_flag)
 	and a
 	ret nz
+
+; jp mn		jp cc,mn
 l208bh:
 	ld l,(iy+001h)
 	ld h,(iy+002h)
 	scf
 	ret
+
+;jr, djnz
 l2093h:
 	ld c,(iy+001h)
 	ld a,c
@@ -5615,30 +5784,39 @@ l2093h:
 	inc hl
 	scf
 	ret
+
+; jp (hl)
 l20a2h:
 	ld hl,(reg.l)
 	scf
 	ret
+
+; Prefix DD
 l20a7h:
 	ld hl,(reg.ix)
 	jr l20afh
+; Prefix FD
 l20ach:
 	ld hl,(reg.iy)
 l20afh:
 	ld a,(iy+001h)
-	cp 0e9h
+	cp 0e9h			; jp (ix); jp (iy)
 	scf
 	ret z
 	and a
 	ret
+
+; Prefix ED
 l20b8h:
 	ld a,(iy+001h)
-	cp 04dh
+	cp 04dh			; reti
 	jr z,l20dch
-	cp 045h
+	cp 045h			; retn
 	jr z,l20dch
 	and a
 	ret
+
+;ret cc
 l20c5h:
 	ld a,(iy+000h)
 	ld (l20d7h),a
@@ -5656,6 +5834,7 @@ l20d7h:
 	inc hl
 	jp (hl)
 
+;ret
 l20dch:
 	ld a,(b_21e2_start)
 	and a
@@ -5667,15 +5846,18 @@ l20dch:
 	pop hl
 	ret
 l20edh:
-	ld hl,(reg_sp)
+	ld hl,(reg_sp)		;break on return address
 	ld e,(hl)
 	inc hl
 	ld d,(hl)
 	ex de,hl
-	call sub_09cah
+	call bp_trace_enter
+;rst 8
+l2115h:
 	and a
 	ret
 
+;rst n
 l20f9h:
 	ld a,(l0003h)
 	cp (iy+000h)
@@ -5693,42 +5875,51 @@ l20f9h:
 l2113h:
 	scf
 	ret
-l2115h:
-	and a
-	ret
+
+;-------------------------------------------------------------------------------
+; >>C[N][J] [steps]
+; >>C[N][J] W expression
+; >>C[N][J] U expression
+;     trace over Calls [No list] [Jumps only] /.While./.Until.
+
 cmd_C:
-	ld hl,cmd_C
 	ld a,1
-	jr l2122h
+	jr cmd_tc
+
+;-------------------------------------------------------------------------------
+; >>T[N][J] [steps]
+; >>T[N][J] W expression
+; >>T[N][J] U expression
+;      Trace [no List] [Jumps only] / .While. / .Until.
+
 cmd_T:
 	xor a
-	ld hl,cmd_T
-l2122h:
+cmd_tc:
 	ld (cmd_rpt),hl
 	ld (trace_call_flag),a
 	call get_char_upper
 	sub 'N'
-	jr nz,l212eh
+	jr nz,tc_non
 	inc de
-l212eh:
+tc_non:
 	ld (trace_N_flag),a
 	call get_char_upper
 	sub 'J'
-	jr nz,l2137h
+	jr nz,tc_noj
 	inc de
-l2137h:
+tc_noj:
 	ld (trace_J_flag),a
-	call sub_21a6h
-	jr z,l2145h
-	ld hl,1
+	call tc_chk_u_or_w
+	jr z,tc_save_uw_expr_ptr
+	ld hl,1				;default: 1 step
 	call get_lastarg_def
-l2145h:
-	ld (trace_count),hl
+tc_save_uw_expr_ptr:
+	ld (trace_cnt_or_ptr),hl
 	sub a
-	ld (l0941h),a
+	ld (bp_p_cpu_flag),a
 l214ch:
-	call sub_1ffeh
-	jr l21a3h
+	call tc_set_bp
+	jr user_go1
 
 l2151h:
 	call bp_clr_temporary
@@ -5739,43 +5930,44 @@ l2151h:
 	call sub_21c8h
 	jr z,l216bh
 	ld hl,b_2048_start
-	call lookup_opc
+	call lookup_op
 	jr nc,l214ch
 l216bh:
-	ld a,(trace_UW_flag)
+	ld a,(trace_UW_flag)		;0 or 'U' or 'W'
 	and a
-	jr z,l2188h
-	ld de,(trace_count)
+	jr z,tc_cnt			;flag is 0, check for step count.
+	ld de,(trace_cnt_or_ptr)
 	call expr
 	ld a,h
 	or l
 	add a,0ffh
 	sbc a,a
-	ld hl,trace_UW_flag
+	ld hl,trace_UW_flag		;'U' or 'W'
 	xor (hl)
-	bit 1,a
+	bit 1,a				;'U' = 55H, 'W' = 57H
 	jr z,l2193h
-l2185h:
-	jp l0902h
-l2188h:
-	ld hl,(trace_count)
+do_break0:				;print registers and go to main loop
+	jp do_break
+
+tc_cnt:
+	ld hl,(trace_cnt_or_ptr)
 	dec hl
-	ld (trace_count),hl
+	ld (trace_cnt_or_ptr),hl
 	ld a,h
 	or l
-	jr z,l2185h
+	jr z,do_break0
 l2193h:
-	call sub_1ffeh
-	jr nc,l2185h
+	call tc_set_bp
+	jr nc,do_break0
 	ld a,(trace_N_flag)
 	ld b,a
-	ld a,(l0941h)
+	ld a,(bp_p_cpu_flag)
 	or b
-	ld (l0941h),a
-l21a3h:
+	ld (bp_p_cpu_flag),a
+user_go1:
 	jp user_go
 
-sub_21a6h:
+tc_chk_u_or_w:
 	call skipbl
 	xor a
 	ld (trace_UW_flag),a
@@ -5813,25 +6005,27 @@ l21dah:
 	cp 045h
 	ret
 
+;-------------------------------------------------------------------------------
+
+con_col:
+	db	0
+
+;-------------------------------------------------------------------------------
+
 b_21e2_start:
 	db	0
 trace_call_flag:
 	db	0		;1=call, 0=trace
 trace_UW_flag:
 	db	0		;0 or 'U' or 'W'
-trace_count:
+trace_cnt_or_ptr:
 	dw	0
 trace_N_flag:
 	db	0		;0 if 'N'
 trace_J_flag:
 	db	0		;0 if 'J'
 
-;-------------------------------------------------------------------------------
-
-con_col:
-	db	0
-
-l0941h:
+bp_p_cpu_flag:
 	db	0
 
 bp_tab:
@@ -5843,8 +6037,6 @@ bp_tab:
 
 expr_p1:
 	dw	expr_buf
-expr_p2:
-	dw	expr_buf
 
 expr_buf:
 current_cseg	defl	$ - current_cseg
@@ -5931,6 +6123,8 @@ current_cseg	defl	$
 	ds	EXPR_BUF_SIZE - ($ - expr_buf)
 expr_bufe:
 
+;-------------------------------------------------------------------------------
+
 msg_Y:
 	dc	'Yn'
 reg_Y:
@@ -5982,6 +6176,9 @@ disas_arg_16:
 disas_argtype:
 	db	0
 
+pbl_loop_adr:
+	dw	0
+
 symlen_cur:		;max length of symbols read so far
 	db	0
 cur_fcb: