Program, which we choose - The possible consequences of using undocumented commands.

<b>Program, which we choose</b> - The possible consequences of using undocumented commands.

    The magazine ZX-FORMAT N4 published an article about the 
possible consequences of using undocumented commands. Since It 
is of interest to All programmers, let me

all her quote with the author spelling.


     ".....................


           Message

         from the firm Nemo.
________________________________


       In microprocessors

          Z84C0010PEC

    [CMOS structure, 10 MHz]
discovered by a team from the discharge
undocumented, implementation
which is different from pre-existing.

              ____


     From the Editor ZX-Format.


    "Excellent" - is an understatement
said, rather it is the opposite, and, naturally, leads to death 
in half the individual cases. Here such here the bases, 
gentlemen good. We are, frankly,

very surprised when ZF # 3 does not
wanted to work on KAY-256
above CPU, and rushed into the
chasing nonexistent glitches in the shell. But the long search
gave no positive result, then a shadow of doubt on
about the search target has crept in
our dark soul. After
as all other possible causes have been studied and discarded as
unjustified as high confidence, the culprit was found and named,
as you already know, was
CPU is the present version, no matter which computer it is 
installed. It follows from this simple and logical conclusion - 
invisible Zilog wrote all the annotations to the family of 
processors "do not use undocumented commands To avoid possible 
incompatibilities with All subsequent versions ...".

anything, this model is very
fresh and non-proliferation
Our Neob'yatnoy, but objectively estimate market Z-80 clearly 
points to the depletion of older models and, consequently, the 
inevitable introduction of recent developments such

weird (weird?) behaves
firm Zilog.

    If you can put in
mind, 2 and 2, and you get
less than five and more than three, then
logical to assume the consequences of this invasion explained 
to you do not need. (Well, those who need to start need to 
break the habit from using their favorite team OUT (# FD), A).


    "And what is this team is that?" - Asks the medium 
statistical hacker lazily twirling separated from the signal 
INT postings. 

    A neskazhu! - The old
Traditionally I will answer him. AND
not only him but also to everyone else. Maybe it is not
bring tangible benefits to the
fight for the "purity code", but,
At least, not make worse.
The main goal, which guided the authors of this paper does not 
imply rejection of the use of any separately vzatoy 
undocumented command, but is widespread rejection of the 
application "The entire list. Perhaps the day of reckoning is 
still not as close as seemed to us, but it's better to know 
about methods for selection of the underworld in advance, so as 
not to tear his hair oposlya. 

    The threat of total incompatibility is imminent in our 
common home. So is not it better to all of us, if individually 
stands in her way. 

    For sim wish you a pleasant
snovedeny and give the word Captain Nemo.

                          (A.P.)

              ____


    Nemo firm says
plans to use this type of processors in the future, since the 
characteristics of the processor most fully satisfy the 
requirements of CPU architecture KAY. For disagree with such a 
situation cases recommended to acquire their own 8 MHz-CPU on

H-MOS structure and change the CPU,
benefit it in the panel.

    While this is the only recorded case of its kind,
However, firms ZILOG, at the request of its authorized 
distributors, does not consider itself bound adhere to a 
specific processing algorithm, undocumented commands, moreover 
- in related architectures they perform other functions.



    From this it follows that
such "misunderstandings" are possible in the future.

   ..........

   .........." End quote.


    It seems to me that this information makes sense to bring in
pages "ZX-Revue," because
the use of undocumented commands in recent
acquired catastrophic. Even developers assemblers are committed 
to supporting as much as possible their number. 


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