CMP V2.13  Copyright (C) 1984, 1985 by White Heron Corporation
           All rights reserved

  old:  smartdrv.asm    (on the left)     Note:  < marks old lines.
  new:  a:smartdrv.asm  (on the right)           > marks new lines.

===============================================================================

6<; Will use IBM extended memory on PC-AT or
7<;      use Above Board on PC, XT, or AT
8<;
9<;
10<;	device = SMARTDRV.sys [bbbb] [/a]

  ----> changed to the following:

6>;; Will use IBM extended memory on PC-AT or
7>;;      use Above Board on PC, XT, or AT, and
8>;;	    use extended, expanded, or upper extended memory on AT&T 6300 PLUS
9>;
10>;
11>;;	device = SMARTDRV.sys [bbbb] [/a] [/u]

===============================================================================

40<;

  ----> changed to the following:

41>;;		/u	Specifies that upper extended memory will be used
42>;;			on the AT&T 6300 PLUS.  Upper extended memory
43>;;			is the memory beginning at FA0000.  It is used
44>;;			to hold the UNIX kernel when the machine is running
45>;;			Simul-Task.  However, when operating as a pure 
46>;;			MS-DOS machine, this 384K of memory is available
47>;;			for SMARTDRIVE.
48>;;			Note that it is an error to specify this switch
49>;;			if the machine is not a 6300 PLUS.

===============================================================================

102>;;	?.??	7/24/87 WSH Added 6300 PLUS support.  This code is marked by
103>;;			    the use of double semi-colons to make it easy to
104>;;			    find.

  ----> inserted before the following old file line:

93<

===============================================================================

125>
126>;; In order to address memory above 1 MB on the AT&T 6300 PLUS, it is
127>;; necessary to use the special OS-MERGE hardware to activate lines
128>;; A20 to A23.  However, these lines can be disabled only by resetting
129>;; the processor.  The return address offset and segment can be found 
130>;; at 40:a2, noted here as RealLoc1.
131>;;
132>BiosSeg	segment at 40h		;; Used to locate 6300 PLUS reset address
133>	org	00a2h
134>RealLoc1 dd	0
135>BiosSeg	ends

  ----> inserted before the following old file line:

113<

===============================================================================

147>;;		The /U configuration using upper extended memory on the 
148>;;		6300 PLUS is a special case of the type 1 configuration.

  ----> inserted before the following old file line:

124<;

===============================================================================

327>;; The internal name of the device driver has been changed from SMARTDRV
328>;; to SMARTAAR to avoid DOS name conflicts with files named SMARTDRV.*
329>;;

  ----> inserted before the following old file line:

302<INT13DEV  LABEL   WORD

===============================================================================

307<	DB	"SMARTDRV"			;Name of device

  ----> changed to the following:

335>	DB	"SMARTAAR"			;Name of device

===============================================================================

387>;;	Data peculiar to AT&T 6300 PLUS.
388>
389>S5_FLAG		DB	0	;; If set, computer is a 6300 PLUS

  ----> inserted before the following old file line:

359<

===============================================================================

3074>;; NOTE: The value at BASE_ADDR is patched during initialization when
3075>;;	 loading a RAMDrive into upper extended memory on a PLUS
3076>;;

  ----> inserted before the following old file line:

3043<BASE_ADDR	LABEL	DWORD	; 24 bit address of start of this RAMDRV

===============================================================================

3190<	MOV	AH,0DFH

  ----> changed to the following:

3224>
3225>;;
3226>;; Enable address line 20 on the PC AT or activate A20-A23 on the 6300 PLUS.
3227>;; The former can be done by placing 0dfh in AH and activating the keyboard
3228>;; processor.  On the PLUS, 90h goes in AL and the port at 03f20h is written.
3229>;; So the combined value of 0df90h can be used for both machines with
3230>;; appropriate coding of the called routine A20.
3231>;;
3232>
3233>;;	MOV	AH,0DFH
3234>	mov	ax,0df90h		;; set up for PLUS or AT

===============================================================================

3248<	MOV	AH,0DDH
3249<	CALL	A20			; Disable address line 20

  ----> changed to the following:

3292>
3293>;;
3294>;; Reset of line A20 on the PC AT requires writing 0ddh to the keyboard
3295>;; processor.  On the PLUS, the appropriate value is 00.
3296>;;
3297>
3298>;;	MOV	AH,0DDH
3299>	mov	ax,0DD00h	;; setup for PLUS or AT. ah for IBM, al for PLUS
3300>	CALL	A20		; Disable address line 20

===============================================================================

3331>;; CS override needed on S5_FLAG to avoid phase errors on
3332>;; forward declaration of this variable.
3333>	cmp	cs:[S5_FLAG],0		;; test for 6300 PLUS
3334>	jnz	A20S5			;; yes, do this code

  ----> inserted before the following old file line:

3280<	CLI

===============================================================================

3376>
3377>;;*	A20S5 - Address enable/disable routine for the 6300 PLUS.
3378>;;
3379>;;	This routine enables lines A20-A23 on the PLUS by writing
3380>;;	to port 03f20h.  Bit 7 turns the lines on, and bit 4 sets
3381>;;	the power-up bit.  To disable the lines, the processor
3382>;;	must be reset.  This is done by saving the world and 
3383>;;	jumping to the ROM 80286 reset code.  Since the power-up bit
3384>;;	is set, the data segment is set to the BiosSeg at 40h
3385>;;	and a jump is then made to the address at RealLoc1.  
3386>;;	At RealLoc1, one can find the CS:IP where the code
3387>;;	is to continue.
3388>;;	 
3389>;;	Uses ax, flags.
3390>;;	Returns with zero flag set.
3391>;;
3392>A20S5:					
3393>	cli
3394>	or	al,al			;; if zero, then resetting processor
3395>	jnz	A20S5Next
3396>	call	RSet			;; must return with entry value of ax
3397>A20S5Next:
3398>	push	dx			;; set/reset port
3399>	mov	dx,3f20h
3400>	out	dx,al
3401>	pop	dx
3402>	xor	al,al
3403>        STI
3404>        RET
3405>
3406>;;* a20S5BOOT -	This code bypasses the processor reset on a reboot
3407>;;		of the 6300 PLUS.  Otherwise the machine hangs.
3408>a20s5BOOT:				;; use this code before reboot
3409>	cli
3410>	jmp short a20s5next
3411>
3412>OldStackSeg	dw	0		;; used during PLUS processor reset
3413>					;; to save the stack segment
3414>
3415>;;* Rset -	Reset the 80286 in order to turn off the address lines
3416>;;		on the 6300 PLUS.  Only way to do this on the
3417>;;		current hardware.  The processor itself can be
3418>;;		reset by reading or writing prot 03f00h
3419>;;
3420>;;  Uses flags.
3421>;;
3422>RSet:
3423>	pusha				;; save world
3424>	push	ds			;; save segments
3425>	push	es
3426>	mov	ax,BiosSeg		;; point to the bios segment
3427>	mov	ds,ax			;; ds -> 40h
3428>assume	ds:BiosSeg
3429>	push	word ptr [RealLoc1]	;; save what might have been here
3430>	push	word ptr [RealLoc1+2]
3431>	mov	word ptr [RealLoc1],cs:[offset ReturnBack] ;; load our return address
3432>	mov	word ptr [RealLoc1+2],cs
3433>assume ds:nothing
3434>	mov	[OldStackSeg],ss	;; save the stack segment, too
3435>	mov	dx,03f00h		;; reset the processor
3436>	in	ax,dx
3437>	nop				
3438>	nop
3439>	nop
3440>	cli
3441>	hlt				;; should never get here
3442>ReturnBack:
3443>	mov	ss,[OldStackSeg]	;; start the recovery
3444>assume ds:BiosSeg
3445>	pop	word ptr [RealLoc1+2]
3446>	pop	word ptr [RealLoc1]
3447>	pop	es
3448>	pop	ds
3449>	popa
3450>	ret		

  ----> inserted before the following old file line:

3321<

===============================================================================

3530<;	out any dirty tracks take a LONG time, so long that we loose

  ----> changed to the following:

3660>;	out any dirty tracks take a LONG time, so long that we lose

===============================================================================

3652<    ; Reset INT 1C vector to trun cache off

  ----> changed to the following:

3782>    ; Reset INT 1C vector to turn cache off

===============================================================================

3732<	MOV	AH,0DFH

  ----> changed to the following:

3862>;;	MOV	AH,0DFH
3863>	mov	ax,0df90h		;; set up for PLUS or AT

===============================================================================

3775<	MOV	AH,0DDH 	; Disable adress line 20
3776<	CALL	A20

  ----> changed to the following:

3906>;;	MOV	AH,0DDH 	; Disable adress line 20
3907>	mov	ax,0DD00h	;; setup for PLUS or AT. ah for IBM, al for PLUS
3908>	cmp	[S5_FLAG],0
3909>	jz	OFF20A
3910>	call	a20s5boot	;; Don't reset the processor on PLUS, this time
3911>	jmp short off20b
3912>off20a:
3913>        CALL    A20
3914>off20b:

===============================================================================

4078>
4079>U_SWITCH	db	0	;; upper extended memory requested on 6300 PLUS

  ----> inserted before the following old file line:

3940<

===============================================================================

4274>
4275>;;
4276>;; 2.5 Check here for 6300 PLUS machine.  First look for Olivetti copyright,
4277>;;     and if found, check id byte at f000:fffd.
4278>;;
4279>
4280>	push	es				;; Olivetti Machine?
4281>	mov	ax,0fc00h			;; Look for 'OL' at fc00:50
4282>	mov	es,ax
4283>	cmp	es:[0050h],'LO'
4284>	jnz	notS5				;; not found
4285>	mov	ax,0f000h
4286>	mov	es,ax
4287>	cmp	word ptr es:[0fffdh],0fc00h	;; look for 6300 plus
4288>	jnz	notS5
4289>	dec	[S5_FLAG]			;; yep, set flag
4290>notS5:
4291>	pop	es
4292>

  ----> inserted before the following old file line:

4134<;

===============================================================================

4411>;; Added for /u switch
4412>	cmp	al,'u'			;; Look for U switch for PLUS
4413>	jnz	A_TEST
4414>	cmp	[S5_FLAG],0		;; No good unless PLUS
4415>	jz	bad_parm
4416>	TEST	[GOTSWITCH],SWITCH_A	;; Already have switch A ?
4417>	JNZ	BAD_PARM
4418>	cmp	[U_SWITCH],0
4419>	jne	bad_parm
4420>	dec	[U_SWITCH]
4421>	jmp	scan_loop
4422>A_TEST:
4423>;;

  ----> inserted before the following old file line:

4252<	CMP	AL,"a"

===============================================================================

4435>;; added for /u switch
4436>	cmp	[U_SWITCH],0
4437>	jne	bad_parm
4438>;;

  ----> inserted before the following old file line:

4263<	OR	[GOTSWITCH],SWITCH_A

===============================================================================

4847>;; Note:  When using upper extended memory on the PLUS, the value 
4848>;;	  at BASE_RESET + 2 is patched to FA during initialization.
4849>;;

  ----> inserted before the following old file line:

4671<BASE_RESET	LABEL	DWORD		; RESMEM driver must patch this value

===============================================================================

5312>	cmp	U_SWITCH,0		;; don't do this for at&t 6300 plus
5313>	jnz	ret005

  ----> inserted before the following old file line:

5133<	PUSH	AX

===============================================================================

5394>
5395>;; If upper extended memory is used on the PLUS, it is necessary to
5396>;; patch the values of base_reset and base_addr to get the addressing right.
5397>;;
5398>	cmp	[U_SWITCH],0		;; patch the code for /U option
5399>	jz	AT001A
5400>	mov	ax,00fah
5401>	mov	word ptr [base_reset+2],ax	;; patching upper address
5402>	mov	word ptr [base_addr+2],ax	;;   to FA from 10
5403>AT001A:
5404>

  ----> inserted before the following old file line:

5213<	MOV	AX,8800H

===============================================================================

5214<	INT	15H		; Get extended memory size

  ----> changed to the following:

5406>	INT	15H			; Get extended memory size

===============================================================================

5410>
5411>;; If running on a 6300 PLUS, it is necessary to subtract any upper extended
5412>;; memory from the value obtained by int 15 to determine the correct memory
5413>;; available for a type /E RAMDrive.  If loading a /U RAMDrive, it is necessary
5414>;; to find out if there IS any upper extended memory.
5415>
5416>	cmp	[U_SWITCH],0		;; did we ask for upper extended memory
5417>	jz	olstuff			;; no
5418>	call	UpperMemCheck		;; yes, see if anything there
5419>	jc	ERR_RET			;; no, quit
5420>	mov	ax,384			;; yes, but max allowed is 384K
5421>	jmp short at001b
5422>olstuff:
5423>	cmp	[S5_FLAG],0		;; if not 6300 PLUS, go on
5424>	jz	at001b
5425>	call	UpperMemCheck		;; yes, see if 384K is there
5426>	jc	at001b			;; no, so int 15h is right
5427>	sub	ax,384			;; yes, subtract 384K
5428>AT001B:
5429>

  ----> inserted before the following old file line:

5218<	MOV	DX,OFFSET ERRMSG2

===============================================================================

5466>
5467>;;* UpperMemCheck - Called by 6300 PLUS to verify existence of
5468>;;		    upper extended memory of 384K at FA0000h
5469>;;
5470>;;	Returns carry set if no upper extended memory.
5471>;;
5472>;;	This routine is called only by a 6300 PLUS, and
5473>;;	it reads the hardware switch DSW2 to do the job.
5474>;;
5475>UpperMemCheck:
5476>	push	ax
5477>	in	al,66h
5478>	and	al,00001111b
5479>	cmp	al,00001011b
5480>	pop	ax
5481>	jnz	nomem
5482>	clc
5483>	ret
5484>nomem:
5485>	stc
5486>	ret

  ----> inserted before the following old file line:

5254<

===============================================================================

6301>s5flagmsg db	" = S5 flag",13,10,"$"
6302>U_msg	  db	" = U Switch", 13,10,'$'

  ----> inserted before the following old file line:

6068<ENDIF

===============================================================================

28 discrepancies.
	File smartdrv.asm has 6075 lines.
	File a:smartdrv.asm has 6310 lines.