• Почему в МК некорректно работает память xdata?

    @yaponchik Автор вопроса
    Вот генерируемый КЕЙЛом файл стартапа
    $NOMOD51
    ;------------------------------------------------------------------------------
    ;  This file is part of the C51 Compiler package
    ;  Copyright (c) 1988-2005 Keil Elektronik GmbH and Keil Software, Inc.
    ;  Version 8.01
    ;
    ;  *** <<< Use Configuration Wizard in Context Menu >>> ***
    ;------------------------------------------------------------------------------
    ;  STARTUP.A51:  This code is executed after processor reset.
    ;
    ;  To translate this file use A51 with the following invocation:
    ;
    ;     A51 STARTUP.A51
    ;
    ;  To link the modified STARTUP.OBJ file to your application use the following
    ;  Lx51 invocation:
    ;
    ;     Lx51 your object file list, STARTUP.OBJ  controls
    ;
    ;------------------------------------------------------------------------------
    ;
    ;  User-defined <h> Power-On Initialization of Memory
    ;
    ;  With the following EQU statements the initialization of memory
    ;  at processor reset can be defined:
    ;
    ; <o> IDATALEN: IDATA memory size <0x0-0x100>
    ;     <i> Note: The absolute start-address of IDATA memory is always 0
    ;     <i>       The IDATA space overlaps physically the DATA and BIT areas.
    IDATALEN        EQU     80H
    ;
    ; <o> XDATASTART: XDATA memory start address <0x0-0xFFFF> 
    ;     <i> The absolute start address of XDATA memory
    XDATASTART      EQU     0     
    ;
    ; <o> XDATALEN: XDATA memory size <0x0-0xFFFF> 
    ;     <i> The length of XDATA memory in bytes.
    XDATALEN        EQU     0      
    ;
    ; <o> PDATASTART: PDATA memory start address <0x0-0xFFFF> 
    ;     <i> The absolute start address of PDATA memory
    PDATASTART      EQU     0H
    ;
    ; <o> PDATALEN: PDATA memory size <0x0-0xFF> 
    ;     <i> The length of PDATA memory in bytes.
    PDATALEN        EQU     0H
    ;
    ;</h>
    ;------------------------------------------------------------------------------
    ;
    ;<h> Reentrant Stack Initialization
    ;
    ;  The following EQU statements define the stack pointer for reentrant
    ;  functions and initialized it:
    ;
    ; <h> Stack Space for reentrant functions in the SMALL model.
    ;  <q> IBPSTACK: Enable SMALL model reentrant stack
    ;     <i> Stack space for reentrant functions in the SMALL model.
    IBPSTACK        EQU     0       ; set to 1 if small reentrant is used.
    ;  <o> IBPSTACKTOP: End address of SMALL model stack <0x0-0xFF>
    ;     <i> Set the top of the stack to the highest location.
    IBPSTACKTOP     EQU     0xFF +1     ; default 0FFH+1  
    ; </h>
    ;
    ; <h> Stack Space for reentrant functions in the LARGE model.      
    ;  <q> XBPSTACK: Enable LARGE model reentrant stack
    ;     <i> Stack space for reentrant functions in the LARGE model.
    XBPSTACK        EQU     0       ; set to 1 if large reentrant is used.
    ;  <o> XBPSTACKTOP: End address of LARGE model stack <0x0-0xFFFF>
    ;     <i> Set the top of the stack to the highest location.
    XBPSTACKTOP     EQU     0xFFFF +1   ; default 0FFFFH+1 
    ; </h>
    ;
    ; <h> Stack Space for reentrant functions in the COMPACT model.    
    ;  <q> PBPSTACK: Enable COMPACT model reentrant stack
    ;     <i> Stack space for reentrant functions in the COMPACT model.
    PBPSTACK        EQU     0       ; set to 1 if compact reentrant is used.
    ;
    ;   <o> PBPSTACKTOP: End address of COMPACT model stack <0x0-0xFFFF>
    ;     <i> Set the top of the stack to the highest location.
    PBPSTACKTOP     EQU     0xFF +1     ; default 0FFH+1  
    ; </h>
    ;</h>
    ;------------------------------------------------------------------------------
    ;
    ;  Memory Page for Using the Compact Model with 64 KByte xdata RAM
    ;  <e>Compact Model Page Definition
    ;
    ;  <i>Define the XDATA page used for PDATA variables. 
    ;  <i>PPAGE must conform with the PPAGE set in the linker invocation.
    ;
    ; Enable pdata memory page initalization
    PPAGEENABLE     EQU     0       ; set to 1 if pdata object are used.
    ;
    ; <o> PPAGE number <0x0-0xFF> 
    ; <i> uppermost 256-byte address of the page used for PDATA variables.
    PPAGE           EQU     0
    ;
    ; <o> SFR address which supplies uppermost address byte <0x0-0xFF> 
    ; <i> most 8051 variants use P2 as uppermost address byte
    PPAGE_SFR       DATA    0A0H
    ;
    ; </e>
    ;------------------------------------------------------------------------------
    
    ; Standard SFR Symbols 
    ACC     DATA    0E0H
    B       DATA    0F0H
    SP      DATA    81H
    DPL     DATA    82H
    DPH     DATA    83H
    
                    NAME    ?C_STARTUP
    
    
    ?C_C51STARTUP   SEGMENT   CODE
    ?STACK          SEGMENT   IDATA
    
                    RSEG    ?STACK
                    DS      1
    
                    EXTRN CODE (?C_START)
                    PUBLIC  ?C_STARTUP
    
                    CSEG    AT      0
    ?C_STARTUP:     LJMP    STARTUP1
    
                    RSEG    ?C_C51STARTUP
    
    STARTUP1:
    
    IF IDATALEN <> 0
                    MOV     R0,#IDATALEN - 1
                    CLR     A
    IDATALOOP:      MOV     @R0,A
                    DJNZ    R0,IDATALOOP
    ENDIF
    
    IF XDATALEN <> 0
                    MOV     DPTR,#XDATASTART
                    MOV     R7,#LOW (XDATALEN)
      IF (LOW (XDATALEN)) <> 0
                    MOV     R6,#(HIGH (XDATALEN)) +1
      ELSE
                    MOV     R6,#HIGH (XDATALEN)
      ENDIF
                    CLR     A
    XDATALOOP:      MOVX    @DPTR,A
                    INC     DPTR
                    DJNZ    R7,XDATALOOP
                    DJNZ    R6,XDATALOOP
    ENDIF
    
    IF PPAGEENABLE <> 0
                    MOV     PPAGE_SFR,#PPAGE
    ENDIF
    
    IF PDATALEN <> 0
                    MOV     R0,#LOW (PDATASTART)
                    MOV     R7,#LOW (PDATALEN)
                    CLR     A
    PDATALOOP:      MOVX    @R0,A
                    INC     R0
                    DJNZ    R7,PDATALOOP
    ENDIF
    
    IF IBPSTACK <> 0
    EXTRN DATA (?C_IBP)
    
                    MOV     ?C_IBP,#LOW IBPSTACKTOP
    ENDIF
    
    IF XBPSTACK <> 0
    EXTRN DATA (?C_XBP)
    
                    MOV     ?C_XBP,#HIGH XBPSTACKTOP
                    MOV     ?C_XBP+1,#LOW XBPSTACKTOP
    ENDIF
    
    IF PBPSTACK <> 0
    EXTRN DATA (?C_PBP)
                    MOV     ?C_PBP,#LOW PBPSTACKTOP
    ENDIF
    
                    MOV     SP,#?STACK-1
    
    ; This code is required if you use L51_BANK.A51 with Banking Mode 4
    ;<h> Code Banking
    ; <q> Select Bank 0 for L51_BANK.A51 Mode 4
    #if 0   
    ;     <i> Initialize bank mechanism to code bank 0 when using L51_BANK.A51 with Banking Mode 4.
    EXTRN CODE (?B_SWITCH0)
                    CALL    ?B_SWITCH0      ; init bank mechanism to code bank 0
    #endif
    ;</h>
                    LJMP    ?C_START
    
                    END
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