I just changed from Turbo Pascal to Borland Pascal and experienced some
problems with that (side effects ?), like differences in the default
initialization value for global variables (TRUE in TP vs FALSE in BP).
It also seems (it is actually the reason why I upgraded...) that the
DELAY() function has been corrected in BP and is now able to handle
nower days processor speed (>133MhZ).
I discovered all that "by chance" and I'd like to know if anybody is
aware of a way to know all the differences between the two products (not
the marketing ones :-), but the tricky ones...) or a FAQ that I could
refer to.

Thank you in advance for any help.

-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-

Bye,
Stefan
--

TP6 and earlier do not do this initialisation so you get whatever was in
memory at this location previously.

      It is a good practice to initialize all variables,
even if you know the defaults are what you want.
      And this also avoids a problem with differences
in results of a program between compiled, and running
in the IDE, which may not reinitialize each time.

I suppose you were going from a pre-TP7 version of Turbo Pascal?
Global variables would not have been initialised. I don't have old TP
to hand, but maybe a non-0 boolean would be regarded as True. The
chances of that would be 255 times more likely than the boolean being
0, so you might have thought they were always initialised to True, but
you should not rely on it. In fact, you're better off not relying on
variables being initialised at all, except for "typed constants".

So - which version of TP were you upgrading from? And how did you
upgrade - CD from Borland?

The fact that an uninitialize variable seems to usually have value 0
is interesting but doesn't really prove anything; it could just be
coincidental.

InitTurbo:

        MOV     DX,SEG DATA             ;Initialize DS
        MOV     DS,DX
        MOV     PrefixSeg,ES            ;Save PSP segment
        XOR     BP,BP                   ;End of stack frame chain
        CALL    ClearDSeg               ;Zero fill data segment
        CALL    Check8086               ;Determine CPU type

DelayCnt        DW      ?

Then add the following after it:

DelayCntHi      dw      ?     ; added for delay bug fix

Then locate the actual division:

        MOV     CX,55
        DIV     CX

Now add the following _between_ the lines:

        ; begin added code for delay bug fix

        push    ax              ; save ax for the second division
        mov     ax,dx
        xor     dx,dx           ; dx:ax := 0:dx
        div     cx              ; ax:=orig dx / 55, dx:=orig dx mod 55
        mov     DelayCntHi,ax   ; save the high part of the cnt
        pop     ax              ; dx:ax = orig dx mod 55: orig ax
                                ; now the division is safe

        ; end code for delay bug fix

This will work up to some 200 GHz machines. After that the delays will
drop to zero.

And finally locate the part where the DelayCnt is used:

@@1:    MOV     AX,DelayCnt
        XOR     DX,DX

Now simply comment the XOR line out and add:

        mov     dx,DelayCntHi  ; added for delay bug fix