Microsoft Macro Assembler  Version 5.10                    5/22/07 09:03:11
sysinit                                                     Page     1-1




				; Initialization for Steve's C&T CS8230 System
				; It works or else complain to admin@stevedeppe.com
				
 0000				primary	segment	use16
					assume	cs:primary,ds:primary,ss:primary
				
 00E0					org	0e0h
					dss	4,mctl		;memory controller data
					dss	1,extf		;if zero, E800-EFFF region found unused
				
 0100					org	100h
 0100				main	proc	near
				
 0100  B8 0305				mov	ax,305h
 0103  33 DB				xor	bx,bx
 0105  CD 16				int	16h		;max keyboard rate, min delay
				
 0107  B8 351E				mov	ax,351eh	;address diskette parameter table
 010A  CD 21				int	21h
 010C  26: C6 47 0A 04			mov	mb es:[bx+10],4	;500ms startup
 0111  26: C6 47 02 FF			mov	mb es:[bx+2],-1	;14-second delay until motor off
				
 0116  E8 048C R			call	sychk		;80386 or later else barf
				
 0119  0F 01 E0				smsw	ax
 011C  24 01				and	al,1
 011E  0F 85 029E R			jnz	pmode		;cpu not in real mode
				
 0122  B0 0A				mov	al,0ah
 0124  E6 22				out	22h,al
 0126  E4 23				in	al,23h
 0128  0A C0				or	al,al
 012A  0F 85 02A5 R			jnz	mcnp		;system has no 82c302
				
				
				; enable 64k ram at A000, 160k-192k ram at C000
				
 012E  B9 0003			mcp:	mov	cx,3
 0131  33 DB				xor	bx,bx
				
 0133  FA				cli			;disable interrupts
 0134  BA 0022			rmcl:	mov	dx,22h		;82c302 controller index port
 0137  B0 0C				mov	al,0ch
 0139  02 C1				add	al,cl
 013B  EE				out	dx,al		;address configuration register
 013C  66| C1 E3 08			shl	ebx,8
 0140  42				inc	dx		;82c302 controller data port
 0141  EC				in	al,dx		;read configuration register
 0142  8A D8				mov	bl,al
 0144  E2 EE				loop	rmcl		;read for FE,DC,BA
 0146  FB				sti			;enable interrupts
				
 0147  66| 89 1E 00E0 R			mov	ml mctl,ebx	;save configuration
 014C  66| 89 1E 0488 R			mov	ml mv2,ebx
 0151  66| B8 0003FFFF			mov	eax,3ffffh
 0157  66| 23 D8			and	ebx,eax
 015A  66| 33 D8			xor	ebx,eax
 015D  0F 85 02AC R			jnz	mcerr		;A000-E7FF must be on I/O channel to start
				
 0161  FA				cli			;disable interrupts
 0162  B8 0DF0				mov	ax,0df0h	;register D, data F0 (B,A)
 0165  E8 01D4 R			call	wctl		;set A000-AFFF system ram, B000-BFFF I/O
 0168  32 C0				xor	al,al		;register E, data 00 (D,C)
 016A  E8 01D4 R			call	wctl		;set C000-DFFF system ram
 016D  A0 00E2 R			mov	al,mctl+2	;prior setting 03-FF (F,E)
 0170  50				push	ax
 0171  24 F0				and	al,0f0h
 0173  E8 01D4 R			call	wctl		;set E000-EFFF system ram, F000-FFFF unchanged
 0176  58				pop	ax
 0177  24 0C				and	al,0ch		;check whether E800-EFFF was in use
 0179  34 0C				xor	al,0ch
 017B  A2 00E4 R			mov	extf,al		;zero if entire region not used
 017E  FB				sti			;enable interrupts
				
				
				; initialize enabled ram to set parity
				
 017F  B8 A000				mov	ax,0a000h
 0182  B9 4000				mov	cx,4000h	;64k/4 (16k dwords)
 0185  E8 01DE R			call	wram		;initialize segment A000-AFFF
 0188  80 C4 20				add	ah,20h
 018B  E8 01DE R			call	wram		;initialize segment C000-CFFF
 018E  80 C4 10				add	ah,10h
 0191  E8 01DE R			call	wram		;initialize segment D000-DFFF
 0194  80 C4 10				add	ah,10h
 0197  F6 06 00E4 R FF			test	mb extf,-1
 019C  74 02				jz	s @f		;region not in use, clear 64k
 019E  D1 E9				shr	cx,1		;clear 32k only
 01A0  E8 01DE R		@@:	call	wram		;initialize segment E000-E[7F]FF
				
				
				; find last mcb in chain
				
 01A3  B4 52			        mov     ah,52h
 01A5  CD 21			        int     21h
 01A7  26: 8B 47 FE			mov	ax,es:[bx-2]
 01AB  8E C0				mov	es,ax		;addr 1st mcb
				
 01AD  33 F6			mcbl:	xor	si,si
 01AF  26: 8B 5C 03			mov	bx,es:[si+3]	;size of block
 01B3  43				inc	bx		;include mcb
				
 01B4  26: 8A 04			mov	al,es:[si]	;mcb flag
 01B7  3C 5A				cmp	al,'Z'
 01B9  74 2D				jz	s lmcb		;end of mcb chain
 01BB  3C 4D				cmp	al,'M'
 01BD  0F 85 02B3 R			jnz	merr		;not an mcb
				
 01C1  8C C0				mov	ax,es
 01C3  03 C3				add	ax,bx
 01C5  8E C0				mov	es,ax		;address next mcb
 01C7  80 FC F0				cmp	ah,0f0h
 01CA  72 E1				jb	mcbl		;continue if not into rom
				
 01CC  BE 0333 R		abug:	mov	si,os mbug
 01CF  B0 FF				mov	al,-1
 01D1  E9 028E R			jmp	errms
				
				
				; write middle ram enable mask register
				
 01D4  86 E0			wctl:	xchg	ah,al
 01D6  E6 22				out	22h,al		;index
 01D8  40				inc	ax
 01D9  86 C4				xchg	al,ah
 01DB  E6 23				out	23h,al		;data
 01DD  C3				ret
				
				; write ram segment ax, length cx
				
 01DE  8E C0			wram:	mov	es,ax
 01E0  33 FF				xor	di,di		;start at 0
 01E2  51				push	cx
 01E3  F3/ 66| AB			rep	stosd		;initialize segment
 01E6  59				pop	cx
 01E7  C3				ret
				
				
				; end block
				
 01E8  26: 8B 44 01		lmcb:	mov	ax,es:[si+1]	;owner
 01EC  0B C0				or	ax,ax
 01EE  74 40				jz	s lbok		;last block is free
 01F0  3D 0008				cmp	ax,8
 01F3  75 35				jnz	s lbpgm		;not system block
				
				
				; block may be a vdisk header, in which case it must be removed
				
 01F5  26: 66| 8B 44 22			mov	eax,ml es:[si+22h]
 01FA  66| 3D 53494456			cmp	eax,53494456h
 0200  75 CA				jnz	s abug		;system block but not vdisk header
				
 0202  06				push	es		;save mcb segment
 0203  B8 3519				mov	ax,3519h
 0206  CD 21				int	21h		;get int 19h vector in es:bx
 0208  8C C0				mov	ax,es
 020A  48				dec	ax		;s/b address of mcb
 020B  59				pop	cx
 020C  3B C1				cmp	ax,cx
 020E  75 BC				jnz	s abug		;int 19 does not vector to this block
 0210  26: 8A 07			mov	al,es:[bx]	;first op code
 0213  3C EA				cmp	al,0eah
 0215  75 B5				jnz	s abug		;not far jump
 0217  51				push	cx		;last mcb segment
 0218  1E				push	ds		;program data segment
 0219  B8 2519				mov	ax,2519h
 021C  26: C5 57 01			lds	dx,es:[bx+1]	;far jump operand
 0220  CD 21				int	21h		;vector to far jump target instead
 0222  1F				pop	ds
 0223  07				pop	es
 0224  26: 89 74 01			mov	es:[si+1],si	;set block as free
 0228  EB 06				jmp	s lbok
				
 022A  8C CB			lbpgm:	mov	bx,cs
 022C  3B C3				cmp	ax,bx
 022E  75 9C				jnz	s abug		;if not this program, then what?
				
				
				; extend mcb chain into enabled middle ram
				
 0230  8C C0			lbok:	mov	ax,es
 0232  26: 03 44 03			add	ax,es:[si+3]
 0236  3D 9FFF				cmp	ax,9fffh
 0239  75 91				jnz	s abug			;ram must end at 9FFF:0
				
 023B  26: 81 44 03 0FFF		add	mw es:[si+3],0fffh	;extend block to seg AFFE
 0241  26: C6 04 4D			mov	mb es:[si],'M'		;not last block
				
 0245  B8 AFFF				mov	ax,0afffh
 0248  8E C0				mov	es,ax
 024A  26: C6 04 4D			mov	mb es:[si],'M'
 024E  26: 66| C7 44 01 10000008	mov	ml es:[si+1],10000008h	;set 64k system block over video area
				
 0257  B8 C000				mov	ax,0c000h
 025A  8E C0				mov	es,ax
 025C  26: C6 04 5A			mov	mb es:[si],'Z'		;new last block
 0260  B8 3000				mov	ax,3000h		;set 192k size
 0263  F6 06 00E4 R FF			test	mb extf,-1
 0268  74 03				jz	s @f			;E800-EFFF region not in use
 026A  80 EC 08				sub	ah,8			;reduce 32k (160k)
 026D  26: 89 44 03		@@:	mov	es:[si+3],ax		;set size
 0271  26: 89 74 01			mov	es:[si+1],si		;owner (free)
				
 0275  C1 E8 06				shr	ax,6			;from paragraphs to kilobytes
 0278  05 02C0				add	ax,704			;total with ram added to mcb chain
 027B  8E C6				mov	es,si
 027D  26: A3 0413			mov	mw es:[413h],ax		;system memory size
				
 0281  B8 5801				mov	ax,5801h
 0284  BB 0001				mov	bx,1
 0287  CD 21				int	21h			;set best-fit allocation strategy
				
				
				; Termination
				
 0289  BE 0366 R		exit:	mov	si,os mcrlf
 028C  32 C0				xor	al,al
 028E  66| C7 06 0484 R 035B	errms:	mov	ml mv1,os pmsg
	R			
 0297  E8 038B R			call	msout		;write message to stdout
 029A  B4 4C			error:	mov	ah,4ch
 029C  CD 21				int	21h		;exit
				
				
				; Problems
				
 029E  BE 02BA R		pmode:	mov	si,os pmms
 02A1  B0 01				mov	al,1
 02A3  EB E9				jmp	s errms
				
 02A5  BE 02D7 R		mcnp:	mov	si,os not302
 02A8  B0 02				mov	al,2
 02AA  EB E2				jmp	s errms
				
 02AC  BE 02FC R		mcerr:	mov	si,os ooctl
 02AF  B0 03				mov	al,3
 02B1  EB DB				jmp	s errms
				
 02B3  BE 0320 R		merr:	mov	si,os mcbms
 02B6  B0 04				mov	al,4
 02B8  EB D4				jmp	s errms
				
				
 02BA				pmms:	da	<źcannot run in virtual modeą>,0
 02D7				not302:	da	<ź82c302 memory controller not foundą>,0
 02FC				ooctl:	da	<źunexpected middle ram mapping: č6ą>,0
 0320				mcbms:	da	<źbroken mcb chainą>,0
 0333				mbug:	da	<źincomprehensible memory configurationą>,0
				
 035B				pmsg:	da	<ąsysinit: >,0
 0366				mcrlf:	da	<źmiddle ram enabled and initializedą>,0
				
 038B				main	endp
 04E1				primary	ends
					end	main