Insanity #01 20 июля 1999

TR-DOS     Программирование

3d2f or 3d30 - TR-DOS journey into the world of delusions.

(C) Surv! V0r


eЄєЇїЎў ° ∙ · √ № ¤ ■ clarify the situation OUTPUT IN BOARD ■ ¤ 
№ √ · ∙ ° ўЎїЇєЄe 



    In search of material for newspapers, I came across this
a funny situation. Programmiruya disk controller is used in its
work, often for access to the routines TR DOS'a, as
known team jp # 3d2f and jp # 3d30. I do not remember when or 
where, I heard, read ... generally recognized that jp # 3d2f - 
this is the most appropriate way to access the TR DOS. What a 
buggy? Naturally jp # 3d30. At the time, blamed the latter 
method. A cursed loudly, though I now can not indicate the 
source, but apparently, somewhere in the ZX REVIEW. The meaning 
of swearing was approximately as follows. Do not use the jp # 
3d30, because on some (brake) Computers do not have time to 
switch ROM TR DOS. 


    Yes, really. Let's think. And as TR DOS does not
time to switch and register PC slip? It is known that
at # 3d2f in TR DOS is:


      # 3d2f nop

      # 3d30 ret


    How, then, the site is not switched TR DOS processor
identifies command nop, if the file jp # 3d2f? If the think of 
it, and In this case, we shall not enter into TR DOS on a 
hypothetical "Brake" computer, and we hang out in BASIC'e - 
because nop not intercepted, and therefore, the following 
command will again nop, a then there is a BASIC'e DJNZ:



      Not switched ROM: # 3d2f nop

                            # 3d30 nop

                            # 3d31 djnz # 3d5b

                            ...


    If the "brake" the computer so buggy, why not
use the jp # 3d2c an alternative called, because there
very, very much nop'ov, so that switch has to be!


    Perhaps the confusion with the exit command in a 
DOS-fetched, and rather, from the evil one. I myself did not 
encounter such problems and nothing more to add I can not.



    In fact, you get to decide which team
use, but all the same jp # 3d30 quickly move to
sub TR DOS, as in any way.