CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

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ibmpc5150
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CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ibmpc5150 »

According to PCEM emulator, CPU ID is recognized as NEC V20 on PC-Tools 4.x

*CPU ID:NEC V20 on PCEM or 86box
Image

I think it can't be changed to Intel 8088.

So I wonder it is impossible to implement CPU ID as Intel 8088.
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omarsis81
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by omarsis81 »

Does it happen in al 8088 machines?
ibmpc5150
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ibmpc5150 »

@omarsis81

No.

It stills appears as NEC V20 on PCEM.

Image

I think this emulation is Not equal to Intel 8088, but NEC V20.

I hope PCEM add i8088 emulation correctly.
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omarsis81
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by omarsis81 »

No, NEC V20 is not emulated, PCem is closer to 8088 than NEC V20 according to this post viewtopic.php?p=3504
This must be a minor bug in the way PC Tools detects the CPU.
MAYBE you set the clock above the 4.77 and PC Tools thinks you have a NEC V20?
ibmpc5150
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ibmpc5150 »

@omarsis81

I tested it as $4.77Mhz with another PC-Tools version too.
This seems to be bug on PCEM/86box, Not PC-Tools.

Why not test it if you doubt?
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omarsis81
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by omarsis81 »

I don't doubt about what you said, I only mention a possibility, but since you already tested with 4.77 mhz there must be a PCem's bug
EluanCM
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by EluanCM »

Quick note: the recently added Xi8088 BIOS knows how to differentiate between new/old 8088s and NEC V20 and works fine with PCem (detects as old 8088)
Greatpsycho
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by Greatpsycho »

ibmpc5150 wrote: Mon 19 Feb, 2018 8:56 pm I hope PCEM add i8088 emulation correctly.
I found the code that distinguishes the NEC V series from the Intel 8086/8088 series. Full source code link is [url=http://www.dcee.net/Files/Programm/C/cputype.arj]here[/url]. This REP bug in the Intel 8086/8088 CPU mentioned in the comments in the code below should be implemented.

Code: Select all

 ; This test differentiates the NEC V20/V30 between the 8088/8086
 ;
 ;   This is done by testing for a bug in the 8088/8086.  In the
 ;   Intel CPUs, if a repeated string instruction with a segment
 ;   override is interrupted by a hardware interrupt, the
 ;   instruction is not continued.


       mov      dl,cpuV20          ; load code for NEC V20
       sti                         ; enable interrupts
       push     si                 ; save si ( could be a register variable)
       mov      si,0               ; Starting with first byte in es
       mov      cx,0ffffh          ; read a complete segment
       rep      lods byte ptr es:[si]  ; rep with a segment override
       ; hardware interrupt is sure to occur during the above instruction
       pop      si                 ; restore si
       or       cx,cx              ; has entire segment been read?
       je       @@t8_16            ; YES: V20 or V30
       mov      dl,cpu8088         ; NO:  must be 8088 or 8086
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ruben_balea
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ruben_balea »

This other program can tell the very exact CPU including bus width:

Code: Select all

; ********************************************************************
; *                                                                  *
; *  CPU v2.2  (c) Septiembre 1992 CiriSOFT                          *
; *            (c) Grupo Universitario de Informática - Valladolid   *
; *                                                                  *
; *    Este programa determina el tipo de microprocesador del equipo *
; *  y devuelve un código ERRORLEVEL indicándolo:                    *
; *                                                                  *
; *               0-8088, 1-8086, 2-NEC V20, 3-NEC V30,              *
; *               4-80188, 5-80186, 6-286, 7-386, 8-486              *
; *                                                                  *
; *   Aviso: Utilizar TASM 2.0 o compatible exclusivamente.          *
; *                                                                  *
; ********************************************************************


cpu            SEGMENT
               ASSUME CS:cpu, DS:cpu

               .386

               ORG   100h
inicio:
               LEA   DX,texto_ini      ; texto de saludo
               MOV   AH,9
               INT   21h               ; imprimirlo
               CALL  procesador?       ; tipo de procesador en AX
               PUSH  AX                ; guardarlo para el final
               LEA   BX,cpus_indice-2  ; tabla de nombres-2
               MOV   CX,0FFFFh         ; número de iteración-1
otro_proc:     INC   CX
               ADD   BX,2
               MOV   DX,[BX]           ; nombre del primer procesador
               CALL  print
               CMP   CX,AX             ; ¿procesador del equipo?
               JNE   no_es_este
               LEA   DX,apuntador_txt  ; sí lo es: indicarlo
               CALL  print
no_es_este:    LEA   DX,separador_txt
               CALL  print
               CMP   CX,7              ; número de CPUs tratadas-1
               JBE   otro_proc
               LEA   DX,texto_fin      ; últimos caracteres
               CALL  print
               MOV   AH,4Ch            ; retornar código errorlevel AL
               INT   21h               ; fin de programa


procesador?    PROC        ; devolver el tipo de microprocesador en AX
               PUSHF
               PUSH  DS
               PUSH  ES
               PUSH  CX
               PUSH  DX
               PUSH  DI
               PUSH  SI
               MOV   AX,CS
               MOV   DS,AX         ; durante la rutina se guardará
               MOV   ES,AX         ; el tipo de procesador en DL:
               MOV   DL,6          ; supuesto un 286 (DL=6) ...
               PUSHF
               POP   AX            ; AX = flags
               AND   AX,0FFFh      ; borrar nibble más significativo
               PUSH  AX
               POPF                ; intentar poner a 0 los 4 bits más
               PUSHF               ; significativos de los flags
               POP   AX
               AND   AX,0F000h     ; seguirán valiendo 1 excepto en
               CMP   AX,0F000h     ; un 80286 o superior
               JE    ni286ni_super
               PUSHF               ; es 286 o superior
               POP   AX
               OR    AX,7000h      ; intentar activar bit 12, 13 ó 14
               PUSH  AX
               POPF
               PUSHF
               POP   AX
               AND   AX,7000h      ; 286 pone bits 12, 13 y 14 a cero
               JZ    cpu_hallada   ; es un 286 (DL=6)
               INC   DL            ; es un 386 (DL=7) ... de momento
               PUSH  DX
               CLI                 ; momento crítico
               MOV   EDX,ESP       ; preservar ESP en EDX
               AND   ESP,0FFFFh    ; borrar parte alta de ESP
               AND   ESP,0FFFCh    ; forzar ESP a múltiplo de 4
               PUSHFD              ; guardar flags en pila (32 bits)
               POP   EAX           ; recuperar flags en EAX
               MOV   ECX,EAX
               XOR   EAX,40000h    ; conmutar bit 18
               PUSH  EAX
               POPFD               ; intentar cambiar este bit
               PUSHFD
               POP   EAX           ; ECX conserva el bit inicial
               XOR   EAX,ECX       ; bit 18 de EAX a 1 si cambió
               SHR   EAX,12h       ; mover bit 18 a bit 0
               AND   EAX,1         ; dejar sólo ese bit
               PUSH  ECX
               POPFD               ; restaurar bit 18 de los flags
               MOV   ESP,EDX       ; restaurar ESP
               STI                 ; permitir interrupciones de nuevo
               POP   DX            ; recuperar tipo de CPU en DL
               CMP   AX,0
               JE    cpu_hallada   ; es 386: DL=7 (bit 18 no cambió)
               INC   DL            ; es 486: DL=8 (bit 18 cambió)
               JMP   cpu_hallada
ni286ni_super: MOV   DL,4          ; supuesto un 80188 ...
               MOV   AX,0FFFFh
               MOV   CL,33
               SHL   AX,CL         ; (80188/80186 toman  CL mod 32)
               JNZ   tipo_bus_proc ; ... lo es, calcular bus (188/186)
               MOV   DL,2          ; no lo es, supuesto un V20 ...
               MOV   CX,0FFFFh
               STI
               DB    0F3h,26h,0ACh ; opcode de REPZ  LODSB ES:
               JCXZ  tipo_bus_proc ; ... lo es, calcular bus (V20/V30)
               XOR   DL,DL         ; ya sólo puede ser un 8088/8086
tipo_bus_proc: STD                 ; transferencias hacia arriba
               LEA   DI,tipo_bus_dest
               MOV   AL,BYTE PTR DS:tipo_bus_byte ; opcode de STI
               MOV   CX,3
               CLI
               REP   STOSB         ; transferir tres bytes
               CLD
               NOP                 ; el INC CX (1 byte) será machacado
               NOP                 ; con STOSB pero aún se ejecutará
               NOP                 ; en un 8086/80186/V30 (y no en un
               INC   CX            ; 8088/80188/V20) porque está en la
tipo_bus_byte: STI                 ; cola de lectura adelantada.
tipo_bus_dest: STI
               JCXZ  cpu_hallada   ; el bus ya era supuesto de 8 bits
               INC   DL            ; resulta que es de 16
cpu_hallada:   MOV   AL,DL
               XOR   AH,AH
               POP   SI
               POP   DI
               POP   DX
               POP   CX
               POP   ES
               POP   DS
               POPF
               RET     ; AX = CPU: 0/1-8088/86, 2/3-NEC V20/V30
procesador?    ENDP    ;           4/5-80188/186, 6-286, 7-386, 8-486


print          PROC
               PUSH  AX
               PUSH  BX
               PUSH  CX
               MOV   AH,9
               INT   21h
               POP   CX
               POP   BX
               POP   AX
               RET
print          ENDP

cpus_indice    DW    i88,i86,v20,v30,i188,i186,i286,i386,i486
i88            DB    "Intel 8088 $"
i86            DB    "Intel 8086 $"
v20            DB    " NEC  V20  $"
v30            DB    " NEC  V30  $"
i188           DB    "Intel 80188$"
i186           DB    "Intel 80186$"
i286           DB    "Intel 80286$"
i386           DB    "Intel 80386$"
i486           DB    "Intel 80486$"

apuntador_txt  DB    " <---$"

texto_ini      LABEL BYTE
               DB    13,10,"CPU Test v2.2  "
               DB    "(c) Septiembre 1992 Ciriaco García de Celis."
               DB    13,10,"  El microprocesador de este "
               DB    "equipo es compatible:",10
separador_txt  DB    13,10,9,9,9,"$"
texto_fin      DB    13,10,"$"

cpu            ENDS
               END   inicio
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Tux
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by Tux »

Hmmm, a program with 386-instructions (" .386" at the beginning) running/testing on (e.g.) a NEC V20 or a 286?

But you can take cpulevel from FreeDOS, public domain by Eric Auer 2004-2008.
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ruben_balea
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ruben_balea »

Tux wrote: Mon 30 Mar, 2020 11:32 am Hmmm, a program with 386-instructions (" .386" at the beginning) running/testing on (e.g.) a NEC V20 or a 286?

But you can take cpulevel from FreeDOS, public domain by Eric Auer 2004-2008.
It only uses 386 instructions on 386 and higher CPUs and CPULEVEL does exactly the same.
.386 was there only to make Tasm 2.0 happy...
Also CPULEVEL won't detect BUS width.
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Tux
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by Tux »

ruben_balea wrote: Mon 30 Mar, 2020 3:58 pm .386 was there only to make Tasm 2.0 happy...
I see, thanks for clarification (didn't check the complete code).
I just compiled cpu.asm with Tasm 2.0 and you are right, it works :)

However, CPULEVEL is Nasm-style syntax and doesn't use this - quite irritating - .386-instruction,
seems to be quite "TASM-special"...
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ruben_balea
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Re: CPU ID:NEC V20 instead of Intel 8088 on PCEM / 86box

Post by ruben_balea »

Yes, TASM is very fussy. I don't know a lot of assembler, just enough to understand not too complex code and write very simple programs.
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