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|
1: ;------------------------------------------------------------------
2: ; Free Model 4P mode boot ROM for xtrs - Version 0.05
3: ; Copyright 1999, Peter W. Cervasio (cervasio@airmail.net)
4: ;------------------------------------------------------------------
5: ; This software may be copied, modified, and used for any purpose
6: ; without fee, provided that (1) the above copyright notice is
7: ; retained, and (2) modified versions are clearly marked as having
8: ; been modified, with the modifier's name and the date included.
9: ;------------------------------------------------------------------
10: ; Checks to see if a disk image is loaded in emulated drive 0. If
11: ; so, it reads the boot sector to 0x4300 and jumps to that address.
12: ; If no disk image loaded, complains and sits in a loop.
13: ;
14: ; This is only useful for the Model 4P mode of operation, and it
15: ; might not work for all programs. Complains if xtrs thinks it's
16: ; in model 1, 3, or 4 mode.
17: ;
18: ; Written with the help of the LS-DOS 6.3.1 source code, which is
19: ; freely avaliable, though Roy Soltoff holds the copyright to it,
20: ; and the Model 4/4P technical reference.
21: ;
22: ; 3-19-99, Tim Mann: Improved disk error handling. Ruled out
23: ; attempts to work in plain Model 4 mode. (v0.03)
24: ; 4-4-99, Tim Mann: Made read loop continue until NMI instead of
25: ; counting 256 bytes; this should let boot sectors of other than
26: ; 256 bytes work. (v0.04) Fixed bug in sending fdc read command;
27: ; don't use fdcmd, since that waits for completion. (v0.05)
28: ;
29: ; TODO:
30: ; possibly write code for the RST handlers as in the real 4P rom
31: ;
32: ; Last modified on Sat Mar 25 21:33:08 PST 2000 by mann
33: ; modified on Mon Mar 15 17:25:49 CST 1999 by petec
34: ;
35: ;------------------------------------------------------------------
36:
37: ;
38: ; misc equates needed
39: ;
40: 3DC0 video equ 3c00h+7*64
41: 4300 bootram equ 4300h ; load to this address
42: 401A goboot equ 401ah ; jump here to run boot sec!
43: ;
44: ; hardware addresses
45: ;
46: 0084 opreg equ 084h ; Operation control
47: 009C romport equ 09ch ; ROM control
48: 00E4 wrnmiport equ 0e4h ; NMI mask register
49: 00EC modport equ 0ech ; speed, etc.
50: ;
51: 00F0 fdccmnd equ 0f0h ; FDC Command register (write)
52: 00F0 fdcstat equ 0f0h ; FDC Status register (read)
53: 00F1 fdctrak equ 0f1h ; FDC Track register (r/w)
54: 00F2 fdcsect equ 0f2h ; FDC Sector register (r/w)
55: 00F3 fdcdata equ 0f3h ; FDC Data register (r/w)
56: 00F4 fdcslct equ 0f4h ; Drive select, SDEN/DDEN,
57:
58: 0000 org 0
59:
60: ; The following three instructions are what you would
61: ; have in RAM at address 0, which would set up the
62: ; Model 4/4P to turn the ROM back on (lsdos does this)
63: ;
64: 0000 F3 start: di ; disable interrupts
65: 0001 3E01 ld a,1 ; map in the ROM
66: 0003 D39C out (romport),a ; do it!
67: ;
68: ; start of "real" ROM instructions
69: ;
70: 0005 C36900 jp contin ; continue farther up
71: ;
72: ; rst 08h through rst 38h jumps (per tech ref)
73: ;
74: 0008 C30040 rst8: jp 4000h
75: 000B 00000000 db 0,0,0,0,0
00
76: 0010 C30340 rst10: jp 4003h
77: 0013 00000000 db 0,0,0,0,0
00
78: 0018 C30640 rst18: jp 4006h
79: 001B 00000000 db 0,0,0,0,0
00
80: 0020 C30940 rst20: jp 4009h
81: 0023 00000000 db 0,0,0,0,0
00
82: 0028 C30C40 rst28: jp 400ch
83: 002B 00000000 db 0,0,0,0,0
00
84: 0030 C30F40 rst30: jp 400fh
85: 0033 00000000 db 0,0,0,0,0
00
86: 0038 C31240 rst38: jp 4012h
87: ;
88: ; Data to load from 4000h to ??
89: ;
90: 003B C9 retdat: ret ; 4000h (rst 8h)
91: 003C 0000 dw 0
92: 003E C9 ret ; 4003h (rst 10h)
93: 003F 0000 dw 0
94: 0041 C9 ret ; 4006h (rst 18h)
95: 0042 0000 dw 0
96: 0044 C9 ret ; 4009h (rst 20h)
97: 0045 0000 dw 0
98: 0047 C9 ret ; 400ch (rst 28h)
99: 0048 0000 dw 0
100: 004A C9 ret ; 400fh (rst 30h)
101: 004B 0000 dw 0
102: 004D C9 ret ; 4012h (rst 38h)
103: 004E 0000 dw 0
104: 0050 C32C01 jp nmiret ; 4015h (nmi)
105: ;
106: 0053 4D4F db 'MO' ; 4P detect by sysinit
107: ;
108: ; code that jumps to the boot sector (401ah)
109: ;
110: 0055 AF xor a
111: 0056 D39C out (romport),a ; disable rom
112: 0058 C30043 jp bootram ; run boot sector
113: ;
114: 0020 retlen equ $-retdat ; size of code
115: ;
116: ; nmi address
117: ;
118: 0066 org 66h
119: ;
120: 0066 C31540 jp 4015h ; std M4 point in RAM
121: ;
122: ; continue booting the machine
123: ;
124: 0069 AF contin: xor a
125: 006A D3E4 out (wrnmiport),a ; disable interrupts
126: 006C 3E01 ld a,1
127: 006E D384 out (opreg),a ; set ram mode
128: 0070 3E50 ld a,01010000b
129: 0072 D3EC out (modport),a ; set speed/vid
130: ;
131: 0074 310042 ld sp,bootram-100h ; set stack pointer
132: ;
133: 0077 213B00 ld hl,retdat ; code for RAM
134: 007A 110040 ld de,4000h ; move it here
135: 007D 012000 ld bc,retlen
136: 0080 EDB0 ldir
137: ;
138: 0082 21003C ld hl,3c00h ; clear video screen
139: 0085 11013C ld de,3c01h
140: 0088 01FF03 ld bc,1023
141: 008B 3620 ld (hl),' '
142: 008D EDB0 ldir
143: ;
144: 008F ED56 im 1
145: ;
146: 0091 CDA000 call chkmdl ; check for model 4p
147: 0094 CDD400 call rstdrv ; restore drive
148: 0097 CCEB00 call z,readbt ; read boot sector
149: 009A C2B900 jp nz,dskerr ; go on error
150: ;
151: 009D C31A40 jmprom: jp goboot ; jump to boot sector
152: ;
153: ; chkmdl - make sure we're in 4P mode
154: ;
155: 00A0 3E05 chkmdl: ld a,5 ; model query
156: 00A2 ED3C dw 3cedh ; emt_misc instr.
157: 00A4 7D ld a,l ; get model in a
158: 00A5 FE05 cp 5 ; model 4p?
159: 00A7 C8 ret z
160: ;
161: ; romerr - rom installed in model 1, 3, or 4 mode!!
162: ;
163: 00A8 F5 romerr: push af
164: 00A9 214901 ld hl,rommsg ; "invalid rom for model"
165: 00AC 11C03D ld de,video
166: 00AF 013100 ld bc,romlen
167: 00B2 EDB0 ldir ; put msg
168: 00B4 C630 add a,'0' ; convert model to ascii
169: 00B6 12 ld (de),a ; stuff onto screen
170: 00B7 18FE jr $ ; and hang
171: ;
172: ; dskerr - error reading disk
173: ;
174: 00B9 217A01 dskerr: ld hl,errtab ; table of error messages
175: 00BC 37 scf ; ensure termination
176: 00BD 1F nxterr: rra ; loop through bits, low first
177: 00BE 3804 jr c,goterr ; go if error bit found
178: 00C0 23 inc hl ; no, step to next message
179: 00C1 23 inc hl
180: 00C2 18F9 jr nxterr
181: 00C4 5E goterr: ld e,(hl) ; get message address
182: 00C5 23 inc hl
183: 00C6 56 ld d,(hl)
184: 00C7 EB ex de,hl
185: 00C8 11C03D ld de,video ; where to show it
186: 00CB 7E chrout: ld a,(hl)
187: 00CC A7 and a
188: 00CD 28FE jr z,$ ; hang in a loop when done
189: 00CF 12 ld (de),a
190: 00D0 23 inc hl
191: 00D1 13 inc de
192: 00D2 18F7 jr chrout
193: ;
194: ; rstdrv - seek track 0 and set up for boot read
195: ;
196: 00D4 3E81 rstdrv: ld a,81h ; drive 0, dden (no nmi)
197: 00D6 D3F4 out (fdcslct),a ; select drive
198: 00D8 3ED0 ld a,0d0h ; force interrupt
199: 00DA CD3901 call fdcmd ; send to fdc
200: 00DD 0600 ld b,0
201: 00DF 10FE djnz $ ; wait a bit
202: 00E1 3E0C ld a,0ch ; restore w/verify
203: 00E3 CD3901 call fdcmd ;
204: 00E6 E699 and 99h ; mask error bits
205: 00E8 C8 ret z ; return if okay
206: 00E9 18CE jr dskerr
207: ;
208: ; readbt - read boot sector from drive 0
209: ;
210: 00EB 110100 readbt: ld de,0001h ; trk 0, sec 1
211: 00EE 210043 ld hl,bootram ; set buffer
212: 00F1 CDFA00 call readsb ; attempt read
213: 00F4 E61C and 1ch ; keep RNF,CRC,LOST DATA
214: 00F6 C8 ret z ; return if no error
215: 00F7 C3B900 jp dskerr ; go on error
216: ;
217: ; readsb - read sector to buffer
218: ;
219: 00FA 0681 readsb: ld b,81h
220: 00FC 0EF4 ld c,fdcslct ; set dden,ds0
221: 00FE ED41 out (c),b ; select
222: 0100 0D dec c ; set to data register
223: 0101 3E18 ld a,18h ; fdc seek command
224: 0103 ED51 out (c),d ; track # to fdc
225: 0105 CD3901 call fdcmd ; send command to fdc
226: 0108 7B ld a,e
227: 0109 D3F2 out (fdcsect),a ; desired sector
228: 010B 3E81 ld a,81h ; dden & ds0
229: 010D D3F4 out (fdcslct),a ; reselect drive
230: 010F 111681 ld de,08116h ; D=DS0, dden, wait
231: ; E=mask to see DRQ or error
232: 0112 3E80 ld a,80h ; fdc read command
233: 0114 D3F0 out (fdccmnd),a ; send command
234: 0116 0664 ld b,100 ; short delay
235: 0118 10FE djnz $
236: 011A 3EC0 ld a,0c0h ; enable intrq
237: 011C D3E4 out (wrnmiport),a
238: 011E DBF0 rdlp1: in a,(fdcstat) ; get status
239: 0120 A3 and e ; test bit 1
240: 0121 28FB jr z,rdlp1
241: 0123 EDA2 ini
242: 0125 7A ld a,d
243: 0126 D3F4 rdlp2: out (fdcslct),a
244: 0128 EDA2 ini
245: 012A 18FA jr rdlp2 ; tight loop waiting for NMI
246: ; jr nz,rdlp2
247: ; in a,(fdcstat)
248: ; ret
249:
250: 012C AF nmiret: xor a
251: 012D D3E4 out (wrnmiport),a ; no interrupts
252: 012F 3E81 ld a,81h ; DS 0, dden
253: 0131 D3F4 out (fdcslct),a
254: 0133 DBF0 in a,(fdcstat)
255: 0135 E3 ex (sp),hl ; discard one level of return address
256: 0136 E1 pop hl
257: 0137 ED45 retn
258:
259: ;
260: ; fdcmd - send command in A to fdc and wait for completion
261: ;
262: 0139 D3F0 fdcmd: out (fdccmnd),a ; send command
263: 013B 0664 ld b,100 ; short delay
264: 013D 10FE djnz $
265: 013F DBF0 fdst: in a,(fdcstat)
266: 0141 CB47 bit 0,a ; busy?
267: 0143 C8 ret z ; return if not
268: 0144 CB7F bit 7,a ; not ready?
269: 0146 C0 ret nz ; return if set
270: 0147 18F6 jr fdst ; else loop
271:
272:
273: ;------------------------------------------------------------------
274: ; messages
275: ;------------------------------------------------------------------
276: ;
277: 0149 54686973 rommsg: db 'This ROM code does NOT work when emulating Model '
20524F4D
20636F64
6520646F
6573204E
4F542077
6F726B20
7768656E
20656D75
6C617469
6E67204D
6F64656C
20
278: 0031 romlen equ $-rommsg
279: ;
280: 017A D4018C01 errtab: dw dskmsg,ecant,elost,ecrc,ernf,ecant,ecant,dskmsg,ecant
8C01A001
B6018C01
8C01D401
8C01
281: 018C elost:
282: 018C 456D756C ecant: db 'Emulator or ROM bug',0
61746F72
206F7220
524F4D20
62756700
283: 01A0 426F6F74 ecrc: db 'Boot sector CRC error',0
20736563
746F7220
43524320
6572726F
7200
284: 01B6 426F6F74 ernf: db 'Boot sector not found on disk',0
20736563
746F7220
6E6F7420
666F756E
64206F6E
20646973
6B00
285: 01D4 596F7520 dskmsg: db 'You do not have a disk image loaded',0
646F206E
6F742068
61766520
61206469
736B2069
6D616765
206C6F61
64656400
286: ;
287: 0000 end start
Statistics:
47 symbols
493 bytes
Symbol Table:
bootram =4300 fdcstat = f0 romerr a8+
chkmdl a0 fdctrak = f1+ romlen = 31
chrout cb fdst 13f rommsg 149
contin 69 goboot =401a romport = 9c
dskerr b9 goterr c4 rst10 10+
dskmsg 1d4 jmprom 9d+ rst18 18+
ecant 18c modport = ec rst20 20+
ecrc 1a0 nmiret 12c rst28 28+
elost 18c nxterr bd rst30 30+
ernf 1b6 opreg = 84 rst38 38+
errtab 17a rdlp1 11e rst8 8+
fdccmnd = f0 rdlp2 126 rstdrv d4
fdcdata = f3+ readbt eb start 0
fdcmd 139 readsb fa video =3dc0
fdcsect = f2 retdat 3b wrnmiport = e4
fdcslct = f4 retlen = 20
|
