mshiels@tmsoft.uucp (Michael A. Shiels) (08/16/89)
title CPUID - Determine CPU & NDP Type
page 58,122
name CPUID
;
; CPUID uniquely identifies each NEC & Intel CPU & NDP.
;
; Notes on program structure:
;
; This program uses four segments, two classes, and one group.
; It demonstrates a useful technique for programmers who generate
; .COM programs. In particular, it shows how to use segment
; classes to re-order segments, and how to eliminate the linker's
; warning message about the absence of a stack segment.
;
; The correspondence between segments and classes is as follows:
;
; Segment Class
; ------- -----
; STACK prog
; DATA data
; MDATA data
; CODE prog
;
; The segments apprear in the above order in the program source
; to avoid forward references in the CODE segment to labels in
; the DATA/MDATA segments. However, because the STACK segment
; appears first in the file, it and all segments in the same
; class are made contiguous by the linker. Thus they precede
; the DATA/MDATA segments in the resulting .COM file because
; the latter are in a different class. In this manner, although
; DATA and MDATA precede CODE in the source file, their order
; is swapped in the .COM file. That way there is no need for
; an initial skip over the data areas to get to the CODE
; segment. As a side benefit, declaring a STACK segment (as
; the first segment in the source) also eliminates the linker's
; warning about that segment missing. Finally, all segments
; are declared to be in the same group so the linker can properly
; resolve offsets.
;
; Note that if you re-assemble the code for any reason, it is
; important to use an assembler later than the IBM version 1.0.
; That version has a number of bugs including an annoying habit
; of alphabetizing segment names in the .OBJ file. If you use
; IBM MASM 2.0, be sure to specify /S to order the segments
; properly.
;
; If the program reports results at variance with your knowledge
; of the system, please contact the author.
;
; Environments tested in:
;
; CPU Speed
; System in MHz CPU NDP
; ------ --------- --- ---
; IBM PC AT 6 Intel 80286 Intel 80287
; IBM PC AT 9 Intel 80286 Intel 80287
; IBM PC AT 6 Intel 80286 none
; IBM PC AT 8.5 Intel 80286 none
; IBM PC 4.77 Intel 8088 Intel 8087-3
; IBM PC 4.77 Intel 8088* Intel 8087-3
; IBM PC XT 4.77 Intel 8088 none
; IBM PC XT 4.77 Intel 8088 Intel 8087-3
; IBM PC Portable 4.77 NEC V20 none
; COMPAQ 4.77 Intel 8088 none
; COMPAQ 4.77 NEC V20 none
; AT&T PC 6300 8 Intel 8086 Intel 8087-2
; AT&T PC 6300 8 NEC V30 Intel 8087-2
; Tandy 2000 8 Intel 80186 none
;
; * = faulty CPU
;
; Program structure:
;
; Group PGROUP:
; Stack segment STACK, byte-aligned, stack, class 'prog'
; Program segment CODE, byte-aligned, public, class 'prog'
; Data segment DATA, byte-aligned, public, class 'data'
; Data segment MDATA, byte-aligned, public, class 'data'
;
; Assembly requirements:
;
; Use MASM 1.25 or later.
; With IBM's MASM 2.0 only, use /S to avoid alphabetizing the
; segment names.
; Use /r option to generate real NDP code.
;
; MASM CPUID/r; to convert .ASM to .OBJ
; LINK CPUID; to convert .OBJ to .EXE
; EXE2BIN CPUID CPUID.COM to convert .EXE to .COM
; ERASE CPUID.EXE to avoid executing .EXE
;
; Note that the linker doesn't warn about a missing stack segment.
;
; Author:
;
; Original code by: Bob Smith May 1985
; Qualitas, Inc.
; 8314 Thoreau Dr.
; Bethesda, MD 20817
;
; Arthur Zachai suggested the technique to distinguish within the
; 808x and 8018x families by exploiting the difference in the
; length of their pre-fetch instruction queues.
;
; Published in PC Tech Journal - April 1986 - Vol 4 No 4
subttl Structures, Records, Equates, & Macros
page
ARG_STR struc
dw ? ; caller's bp
ARG_OFF dw ? ; caller's offset
ARG_SEG dw ? ; segment
ARG_FLG dw ? ; flags
ARG_STR ends
; Record to define bits in the CPU's & NDP's flags' registers
CPUFLAGS record RO:1,NT:1,IOPL:2,OF:1,DF:1,IF:1,TF:1,SF:1,ZF:1,R1:1,AF:1,R2:1,PF:1,R3:1,CF:1
NDPFLAGS record R4:3,IC:1,RC:2,PC:2,IEM:1,R5:1,PM:1,UM:1,OM:1,ZM:1,DM:1,IM:1
; FLG_PIQL Pre-fetch instruction queue length, 0 => 4-byte
; 1 => 6-byte
; FLG_08 Intel 808x
; FLG_NEC NEC V20 or V30
; FLG_18 Intel 8018x
; FLG_28 Intel 8028x
; FLG_87 Intel 8087
; FLG_287 Intel 80287
;
; FLG_CERR Faulty CPU
; FLG_NERR Faulty NDP switch setting
FLG record RSVD:9,FLG_NERR:1,FLG_CERR:1,FLG_NDP:2,FLG_CPU:3
; CPU-related flags
FLG_PIQL equ 001b shl FLG_CPU
FLG_08 equ 000b shl FLG_CPU
FLG_NEC equ 010b shl FLG_CPU
FLG_18 equ 100b shl FLG_CPU
FLG_28 equ 110b shl FLG_CPU
FLG_8088 equ FLG_08
FLG_8086 equ FLG_08 or FLG_PIQL
FLG_V20 equ FLG_NEC
FLG_v30 equ FLG_NEC or FLG_PIQL
FLG_80188 equ FLG_18
FLG_80186 equ FLG_18 or FLG_PIQL
FLG_80286 equ FLG_28 or FLG_PIQL
; NDP-related flags
; 00b shl FLG_NDP Not Present
FLG_87 equ 01b shl FLG_NDP
FLG_287 equ 10b shl FLG_NDP
BEL equ 07h
LF equ 0ah
CR equ 0dh
EOS equ '$'
POPFF macro
local L1,L2
jmp short L2 ; skip over IRET
L1:
iret ; pop the cs & ip pushed below along
; with the flags, our original purpose
L2:
push cs ; prepare for IRET by pushing cs
call L1 ; push ip, jump to IRET
endm ; POPFF macro
TAB macro TYP
push bx ; save for a moment
and bx,mask FLG_&TYP ; isolate flags
mov cl,FLG_&TYP ; shift amount
shr bx,cl ; shift to low-order
shl bx,1 ; times two to index table of words
mov dx,TYP&MSG_TAB[bx] ; ds:dx => descriptive message
pop bx ; restore
mov ah,09h ; function code to display string
int 21h ; request dos service
endm ; TAB macro
page
INT_VEC segment at 0 ; start INT_VEC segment
dd ? ; pointer to INT 00h
INT01_OFF dw ? ; pointer to INT 01h
INT01_SEG dw ?
INT_VEC ends ; end INT_VEC segment
PGROUP group STACK,CODE,DATA,MDATA
; The following segment both positions class 'prog' segments lower in
; memory than others so the first byte of the resulting .COM file is
; in the CODE segment, as well as satisfies the LINKer's need to have
; a stack segment.
STACK segment byte stack 'prog' ; start STACK segment
STACK ends ; end STACK segment
I11_REC record I11_PRN:2,I11_RSV1:2,I11_COM:3,I11_RSV2:1,I11_DISK:2,I11_VID:2,I11_RSV3:2,I11_NDP:1,I11_IPL:1
DATA segment byte public 'data' ; start DATA segment
assume ds:PGROUP
OLDINT01_VEC label dword ; save area for original INT 01h handler
OLDINT01_OFF dw ?
OLDINT01_SEG dw ?
NDP_CW label word ; save area for NDP control word
db ?
NDP_CW_HI db 0 ; high byte of control word
NDP_ENV dw 7 dup(?) ; save area for NDP environment
DATA ends
subttl Message Data Area
page
MDATA segment byte public 'data' ; start MDATA segment
assume ds:PGROUP
MSG_START db 'CPUID -- Version 1.0'
db CR,LF,CR,LF,EOS
MSG_8088 db 'CPU is an Intel 8088.'
db CR,LF,EOS
MSG_8086 db 'CPU is an Intel 8086.'
db CR,LF,EOS
MSG_V20 db 'CPU is an NEC V20.'
db CR,LF,EOS
MSG_V30 db 'CPU is an NEC V30.'
db CR,LF,EOS
MSG_80188 db 'CPU is an Intel 80188.'
db CR,LF,EOS
MSG_80186 db 'CPU is an Intel 80186.'
db CR,LF,EOS
MSG_UNK db 'CPU is a maverick -- 80288??.'
db CR,LF,EOS
MSG_80286 db 'CPU is an Intel 80286.'
db CR,LF,EOS
CPUMSG_TAB label word
dw PGROUP:MSG_8088 ; 000 = Intel 8088
dw PGROUP:MSG_8086 ; 001 = Intel 8086
dw PGROUP:MSG_V20 ; 010 = NEC V20
dw PGROUP:MSG_V30 ; 011 = NEC V30
dw PGROUP:MSG_80188 ; 100 = Intel 80188
dw PGROUP:MSG_80186 ; 101 = Intel 80186
dw PGROUP:MSG_UNK ; 110 = ?
dw PGROUP:MSG_80286 ; 111 = Intel 80286
NDPMSG_TAB label word
dw PGROUP:MSG_NDPX ; 00 = No NDP
dw PGROUP:MSG_8087 ; 01 = Intel 8087
dw PGROUP:MSG_80287 ; 10 = Intel 80287
MSG_NDPX db 'NDP is not present.'
db CR,LF,EOS
MSG_8087 db 'NDP is an Intel 8087.'
db CR,LF,EOS
MSG_80287 db 'NDP is an Intel 80287.'
db CR,LF,EOS
CERRMSG_TAB label word
dw PGROUP:MSG_CPUOK ; 0 = CPU healthy
dw PGROUP:MSG_CPUBAD ; 1 = CPU faulty
MSG_CPUOK db 'CPU appears to be healthy.'
db CR,LF,EOS
MSG_CPUBAD label byte
db BEL,'*** CPU incorrectly allows interrupts '
db 'after a change to SS ***',CR,LF
db 'It should be replaced with a more recent '
db 'version as it could crash the',CR,LF
db 'system at seemingly random times.',CR,LF,EOS
NERRMSG_TAB label word
dw PGROUP:MSG_NDPSWOK ; 0 = NDP switch set correctly
dw PGROUP:MSG_NDPSWERR ; 1 = NDP switch set incorrectly
MSG_NDPSWOK db EOS ; no message
MSG_NDPSWERR label byte
db '*** Although there is an NDP installed '
db 'on this sytem, the corresponding',CR,LF
db 'system board switch is not properly set. '
db 'To correct this, flip switch 2 of',CR,LF
db 'switch block 1 on the system board.',CR,LF,EOS
MDATA ends ; end MDATA segment
subttl Main Routine
page
CODE segment byte public 'prog' ; start CODE segment
assume cs:PGROUP,ds:PGROUP,es:PGROUP
org 100h ; skip over PSP
INITIAL proc near
mov dx,offset ds:MSG_START ; starting message
mov ah,09h ; function code to display string
int 21h ; request DOS service
call CPUID ; check the CPU's identity
TAB CPU ; display CPU results
TAB NDP ; display NDP results
TAB CERR ; display CPU ERR results
TAB NERR ; display NDP ERR results
ret ; return to DOS
INITIAL endp ; end INITIAL procedure
subttl CPUID Procedure
page
CPUID proc near ; start CPUID procedure
assume cs:PGROUP,ds:PGROUP,es:PGROUP
; This procedure determines the type of CPU and NDP (if any) in use.
;
; The possibilities include:
;
; Intel 8086
; Intel 8088
; NEC V20
; NEC V30
; Intel 80186
; Intel 80188
; Intel 80286
; Intel 8087
; Intel 80287
;
; Also checked is whether or not the CPU allows interrupts after
; changing the SS register segment. If the CPU does, it is faulty
; and should be replaced.
;
; Further, if an NDP is installed, non-AT machines should have a
; system board switch set. Such a discrepancy is reported.
;
; On exit, BX contains flag settings (as defined in FLG record) which
; the caller can check. For example, to test for an Intel 80286, use
;
; and bx,mask FLAG_CPU
; cmp bx,FLG_80286
; je ITSA286
irp XX,<ax,cx,di,ds,es> ; save registers
push XX
endm
; test for 80286 -- this CPU executes PUSH SP by first storing SP on
; stack, then decrementing it. earlier CPU's decrement, THEN store.
mov bx,FLG_28 ; assume it's a 286
push sp ; only 286 pushes pre-push SP
pop ax ; get it back
cmp ax,sp ; check for same
je CHECK_PIQL ; they are, so it's a 286
; test for 80186/80188 -- 18xx and 286 CPU's mask shift/rotate
; operations mod 32; earlier CPUs use all 8 bits of CL.
mov bx,FLG_18 ; assume it's an 8018x
mov cl,32+1 ; 18x masks shift counts mod 32
; note we can't use just 32 in CL
mov al,0ffh ; start with all bits set
shl al,cl ; shift one position if 18x
jnz CHECK_PIQL ; some bits still on,
; so its a 18x, check PIQL
; test for V20
mov bx,FLG_NEC ; assume it's an NEC V-series CPU
call CHECK_NEC ; see if it's an NEC chip
jcxz CHECK_PIQL ; good guess, check PIQL
mov bx,FLG_08 ; it's an 808x
subttl Check Length of Pre-Fetch Instruction Queue
page
; Check the length of the pre-fetch instruction queue (PIQ).
;
; xxxx6 CPUs have a PIQ length of 6 bytes,
; xxxx8 CPUs have a PIQ length of 4 bytes
;
; Self-modifying code is used to distinguish the two PIQ lengths.
CHECK_PIQL:
call PIQL_SUB ; handle via subroutine
jcxz CHECK_ERR ; if CX is 0, INC was not executed,
; hence PIQ length is 4
or bx,FLG_PIQL ; PIQ length is 6
subttl Check for Allowing Interrupts After POP SS
page
; Test for faulty chip (allows interrupts after change to SS register)
CHECK_ERR:
xor ax,ax ; prepare to address
; interrupt vector segment
mov ds,ax ; DS points to segment 0
assume ds:INT_VEC ; tell the assembler
cli ; nobody move while we swap
mov ax,offset cs:INT01 ; point to our own handler
xchg ax,INT01_OFF ; get and swap offset
mov OLDINT01_OFF,ax ; save to restore later
mov ax,cs ; our handler's segment
xchg ax,INT01_SEG ; get and swap segment
mov OLDINT01_SEG,ax ; save to restore later
; note we continue with interrupts disabled to avoid
; an external interrupt occuring during this test
mov cx,1 ; initialize a register
push ss ; save ss to store back into itself
pushf ; move flags
pop ax ; ... into ax
or ax,mask TF ; set trap flag
push ax ; place onto stack
POPFF ; ... and then into effect
; some CPUs effect the trap flag
; immediately, some
; wait one instruction
nop ; allow interrupt to take effect
POST_NOP:
pop ss ; change the stack segment register
; (to itself)
dec cx ; normal cpu's execute this instruction
; before recognizing the single-step
; interrupt
hlt ; we never get here
INT01:
; Note: IF=TF=0
; If we're stopped at or before POST_NOP, continue on
push bp ; prepare to address the stack
mov bp,sp ; hello, Mr. stack
cmp [bp].ARG_OFF,offset cs:POST_NOP ; check offset
pop bp ; restore
ja INTO1_DONE ; we're done
iret ; return to caller
INTO1_DONE:
; restore old INT 01h handler
les ax,OLDINT01_VEC ; ES:AX ==> old INT 01h handler
assume es:nothing ; tell the assembler
mov INT01_OFF,ax ; restore offset
mov INT01_SEG,es ; ... and segment
sti ; allow interrupts again (IF=1)
add sp,3*2 ; strip ip, cs, and flags from stack
push cs ; setup ds for code below
pop ds
assume ds:PGROUP ; tell the assembler
jcxz CHECK_NDP ; if cx is 0, the dec cx was executed,
; and the cpu is ok
or bx,mask FLG_CERR ; it's a faulty chip
subttl Check For Numeric Data Processor
page
; Test for a Numeric Data Processor -- Intel 8087 or 80287. The
; technique used is passive -- it leaves the NDP in the same state in
; which it is found.
CHECK_NDP:
cli ; protect FNSTENV
fnstenv NDP_ENV ; if NDP present, save
; current environment,
; otherwise, this instruction
; is ignored
mov cx,50/7 ; cycle this many times
loop $ ; wait for result to be stored
sti ; allow interrupts
fninit ; initialize processor to known state
jmp short $+2 ; wait for initialization
fnstcw NDP_CW ; save control word
jmp short $+2 ; wait for result to be stored
jmp short $+2
cmp NDP_CW_HI,03h ; check for NDP initial control word
jne CPUID_EXIT ; no NDP installed
int 11h ; get equipment flags into ax
test ax,mask I11_NDP ; check NDP-installed bit
jnz CHECK_NDP1 ; it's correctly set
or bx,mask FLG_NERR ; mark as in error
CHECK_NDP1:
and NDP_CW,not mask IEM ; enable interrupts
; (IEM=0, 8087 only)
fldcw NDP_CW ; reload control word
fdisi ; disable interrupts (IEM=1) on 8087,
; ignored by 80287
fstcw NDP_CW ; save control word
fldenv NDP_ENV ; restore original NDP environment
; no need to wait
; for environment to be loaded
test NDP_CW,mask IEM ; check interrupt enable mask
; (8087 only)
jnz CPUID_8087 ; it changed, hence NDP is an 8087
or bx,FLG_287 ; NDP is an 80287
jmp short CPUID_EXIT ; exit with falgs in BX
CPUID_8087:
or bx,FLG_87 ; NDP is an 8087
CPUID_EXIT:
irp XX,<es,ds,di,cx,ax> ; restore registers
pop XX
endm
assume ds:nothing,es:nothing
ret ; return to caller
CPUID endp ; end CPUID procedure
subttl Check For NEC V20/V30
page
CHECK_NEC proc near
; The NEC V20/V30 are very compatible with the Intel 8086/8088.
; The only point of "incompatibility" is that they do not contain
; a bug found in the Intel CPU's. Specifically, the NEC CPU's
; correctly restart an interrupted multi-prefix string instruction
; at the start of the instruction. The Intel CPU's incorrectly
; restart in the middle of the instruction. This routine tests
; for that situation by executing such an instruction for a
; sufficiently long period of time for a timer interrupt to occur.
; If at the end of the instruction, CX is zero, it must be an NEC
; CPU; if not, it's an Intel CPU.
;
; Note that we're counting on the timer interrupt to do its thing
; every 18.2 times per second.
;
; Here's a worst case analysis: An Intel 8088/8086 executes 65535
; iterations of LODSB ES[SI] in 2+9+13*65535 = 851,966 clock ticks.
; If the Intel 8088/8086 is running at 10 MHz, each clock tick is
; 100 nanoseconds, hence the entire operation takes 85 milliseconds.
; If the timer is running at normal speed, it interrupts the CPU every
; 55ms and so should interrupt the repeated string instruction at least
; once.
mov cx,0ffffh ; move a lot of data
sti ; ensure timer enabled
; execute multi-prefix instruction. note that the value of ES as
; well as the direction flag setting is irrelevant.
push ax ; save registers
push si
rep lods byte ptr es:[si]
pop si ; restore
pop ax
; on exit: if cx is zero, it's an NEC CPU, otherwise it's an Intel CPU
ret ; return to caller
CHECK_NEC endp
subttl Pre-Fetch Instruction Queue Subroutine
page
PIQL_SUB proc near
; This subroutine discerns the length of the CPU's pre-fetch
; instruction queue (PIQ).
;
; The technique used is to first ensure that the PIQ is full, then
; change an instruction which should be in a 6-byte PIQ but not in a
; 4-byte PIQ. Then, if the original instruction is executed, the PIQ
; is 6-bytes long; if the new instruction is executed, PIQ length is 4.
;
; We ensure the PIQ is full be executing an instruction which takes
; long enough so that the Bus Interface Unit (BIU) can fill the PIQ
; while the instruction is executing.
;
; Specifically, for all byt the last STOSB, we're simple marking time
; waiting for the BIU to fill the PIQ. The last STOSB actually changes
; the instruction. By that time, the orignial instruction should be in
; a six-byte PIQ byt not a four-byte PIQ.
assume cs:PGROUP,es:PGROUP
@REP equ 3 ; repeat the store this many times
std ; store backwards
mov di,offset es:LAB_INC+@REP-1 ; change the instructions
; at ES:DI
; and preceding
mov al,ds:LAB_STI ; change to a sti
mov cx,@REP ; give the BIU time
; to pre-fetch instructions
cli ; ensure interrupts are disabled,
; otherwise a timer tick
; could change the PIQ filling
rep stosb ; change the instruction
; during execution of this instruction
; the BIU is refilling the PIQ. The
; current instruction is no longer
; in the PIQ.
; Note at end, CX is 0.
; The PIQ begins filling here
cld ; restore direction flag
nop ; PIQ fillers
nop
nop
; The following instruction is beyond a four-byte-PIQ CPU's reach,
; but within that of a six-byte-PIQ CPU.
LAB_INC label byte
inc cx ; executed only if PIQ length is 6
LAB_STI label byte
rept @REP-1
sti ; restore interrupts
endm
ret ; return to caller
assume ds:nothing,es:nothing
PIQL_SUB endp ; end PIQL_SUB procedure
CODE ends ; end code segment
if1
%OUT Pass 1 Complete
else
%OUT Pass 2 Complete
endif
end INITIAL ; end CPUID module