Intel 386 manual Software Routine to Reco.gnize the Coprocessor

COPROCESSOR HARDWARE INTERFACE

~B~b/67/~~/lab		MACRO ASSEMBLER	Test for presence of a Numerics Chip.	Revision 1."	PAGE 1
DOS	3.2B (B33-NlaB~b/671a6/16b		MACRO ASSEMBLER V2.B ASSEMBLY Of MODULE	TEST- NPX
OBJECT MODULE PLACED IN fINDNPX.oBJ
LaC	OBJ	LINE	SOURCE

+1 StitleC'Test for presence of a Numerics Chip. Revision 1.0')

nalle Test_NPX

stack segment stack ' stack'

BBBB(18B

1111 l

e9C8 1111	7	sst
	~	stack
	9	data
	18
	11	temp
	12	data
	13
	H	dgroup
	15	cgroup
	lb
	17	code
	18
	19	start:
	2B
	21
	22	,
	23
	2~

dw lBB dup (? l

dw ends

segment public 'data'

dw Bh

ends

group data, stack group code

segllent public 'code'

assume cs: cgroup, ds: dgroup

Look for an 8B87. 8B287. i387 SX or i387 DX NPX.

Note that we cannot execute WAIT on lIB8b/M if no 8887 is present.

BBBB		25	test_npx:			; nust use non"wait form
BBBB	9BDBE3	2b	fninit
BBB3	BEBBBB	27	mov	si ,offset	dgroup: terap
BBBb	C7B~5A5A	2~	mov	word ptr [sil,SASAH ; Initialize temp to non-zero value
BBBBA	9BDD3C	29	fnstsw	[sil		nust use non-wait form of fstsw
		3B				It is not necessary to use a blAIT instruction
		31				after fnstsw or fnstew. Do not use one here.
BBn	aB3CBB	32	cmp	byte ptr	[sil,"	See if correct" status with zeroes was read
BB1B	752A	33	jne	no_npx		Jump if not a valid status word. meaning no NPX
		3~

35Naill see if ones .can be correctly written from the control word.

3b

BB12	9BD93C	37	fnstcw	[sil	Look at the control word; do not use k1AIT form
		38		ax. [sil	»0 not use a IIIAIT instruction here!
BB15	~aB~	39	mov		See if ones can be written by NPX
BB17	253f18	~B	and	ax. 193fh	See if selected parts of control. word look OK
BB1A	3D3fBB	~l	cmp	ax.3fh	{heck that· ones and zeroes were correctly read
BBH'751D		~2	jne	no_npx	Jump if no NPX is installed
		~3

~~Somne numerics chip is installed. NPX -instructions and. klAIT are nOIll safe.

~5 See if the NPX is an 8B~7. ~B2a7. i387 SX or i387 DX NPX

~b This code is necessary if a denormal exception handler is used or the

~7 new i367 J)X NPX instructions will be used .

. ~6

Figure 5-3.Software Routine to Reco.gnize the Coprocessor

5-7