Polesse #11 29 сентября 1999

Железо

Laboratory - Overclocking Computer "Byte".

                         LABORATORY



                    CRACKDOWN ON COMPUTER "byte"


(C) PAVEL



    Hello, dear users ZX-SPECTRUM. The text that will be 
discussed below, is addressed to a greater extent, PC users, 
"bytes", but I do not think that this information interfere 
with other users SPECCY. 

    It is no secret that there are computers having the memory 
128 KB, but because of certain characteristics, they do not 
work for some programs. Partial solution of these issues and is 
dedicated to my article.



                            INTRODUCTION


    I've been doing Spectrum only four years (including year 
and a half iron). My car "BAIT 512K with some revisions, of 
which will be discussed. Further development is important 
because increases rabotayushih number of programs and 
unemployed can be counted, literally on the fingers. Earn 
"Black Crow" and change the world dem. 

    The problem lies in the hardware of the computer "byte", and
namely the presence of two fields of memory. Schematically, the 
PC memory "byte" as follows (sm.tabl.1).



                                                    TABLE 1.0


      ADDRESS TYPE MEMORY CTTA / INT OUTPUT


    # 0000 - # 3FFF ROM 48 69 872 99.817%

    # 0000 - # 3FFF ROM 128 69 872 99.817%

    # 4000 - # 7FFF VIDEO-0 56 644 80.920%

                   (Bank 5)

    # 8000 - # BFFF Bank 2 69 872 99.817%



    Further configuration is determined by the specific schemes 
to enhance your computer. I came across only two alternatives, 
and determine what you have is quite simple. To do this, look 
inside your computer. If your car are soldered on top of one 
chip KP565RU5 (B, C, D), yet KR565RU5 eight (B, C, D) 
(conventionally denoted this type of expansion, as "A"), then 
Table 1 can be extended: 


                                                    TABLE 1.1


      ADDRESS TYPE MEMORY CTTA / INT OUTPUT


    # C000-# FFFF Bank 0 69 872 99.817%

      --//-- Bank 1 - / / - --//-
      --//-- Bank 3 - / / - --//-
      --//-- Bank 4 - / - --//-
      --//-- Bank 6 - / - --//-
      --//-- Video 1 56 644 80.920%

                   (Bank 7)



    Otherwise (if the chip KR565RU5 (B, C, D) surface is not 
established, then this extension type "B" - The most common 
option.) And table 1 has a slightly different form: 


                                                    TABLE 1.2


      ADDRESS TYPE MEMORY CTTA / INT OUTPUT


    # C000-# FFFF Bank 0 69 872 99.817%

      --//-- Bank 1 - / / - --//-
      --//-- Bank 3 - / / - --//-
      --//-- Bank 4 56 644 80.920%

      --//-- Bank 6 - / - --//-
      --//-- Videos 1 - / - --//-
                   (Bank 7)



    Result from the presence of the slow memory are:


      1) slow loading, or a complete load of games and

         magazines (SQ.HEAD, LED STORM, CV-1 (second disk), etc.

         etc.)

      2) refusal to work the system software and games, demos

         (The list is large).



                            DECISION


    Thus, I (like everyone else!) The owner of "BAYT'a collided
with this problem, and somehow had to find a way out. And get 
by reading HELP'ik to "RAM TEST'u" I came across the revised 
scheme Lviv option Speccy. The essence of the revision was to 
change address space on the regeneration of the slow (video)

memory for quick and thereby recover the memory (and
perform the internal team and regeneration) at the speed of the 
upper (Fast) memory. For a computer "byte" a similar scheme 
should be have the form:



                 DD1.1 DD1.2


         RFSH ''

                     O O NEW

         OLD



    DD1 K555LA3 or KR1533LA3;


    Signal RFSH bremsstrahlung take from 28 feet Z80. Then you 
should vypayat 3 foot chip D21 (LI1). OLD signal is taken from 
vypayannoy foot chip D21, and the place vypayannoy leg throw 
light NEW. 


    Attention! Non-chips listed on the scheme published in the 
Journal of hams. YOUR COMPUTER "7.8 for 1996: 

                                              Number 7 p. 24-25

                                              Number 8 p. 20-22

   Or you may like:

                             DD1.1


                     RFSH '

                                      NEW

                     OLD



    Enter this revision for the expansion of type "B", without 
any problems is the second CD, "Raven-1, but for shipments 
speed is not enough. 

    To further accelerate the on-screen memory area, I refined 
it a bit and she took the following form: 


               DD1.1 DD1.2

              April 1

        OLD '3' 6

              2 O 5, O new

      RFSH


                 DD2.1 DD1.3

        DDX 1 September DD2.3

       9 1 3 'Sept. 8

          'O 2 August 1910 1 August DD1.4
 INT 10 O 12 October

                                 3.5MGts' 11

                                                  13 O TAKT

                                         DD2.4

                                       12

                                           January 1911

                                       13

                                   7MHz


    DD1 K555LA3 (KR1533LA3)

    DD2 K555LL1 (KR1533LL1)

    DDX free log. element in the computer DD16 (K555LA3)


    Note: This plan may be made at LL1 and KP11

    ie as in this case requires two chips.


  Signals OLD and NEW are the same as in the diagram above;

  INT signal we take from 8 feet DD14 (KR1533LL1) or 16 feet 
Z80; 

  3.5 MHz shoot from 9 feet DD19 (KR1533LN1), and 7MHz from 2 
feet 

  IC DD12 (KR1533LN1);

  Signal TAKT throw of 10 feet DD26 (K155LA4) previously

  vypayav 8 foot DD19 (!).


    As can be seen from the scheme, the processor Z80, during 
active the signal is put ReFreSH clock frequency 7 MHz, so also 
an important condition of this scheme is a kind of processor 
Z80. Normal operation is possible if the set Z80B (6 MHz), Z80H 
(High Speed ​​8 MHz) or some chips Z80A (Z8400A, Z84C0006PEC 
and some others), well, it is best Z84C010PEC (or Z84C008, 
Z84C006). 


    The reason for the acceleration of this scheme is simple 
enough. In two words - it is a translation of the processor at 
7MHz during decoding, perform the operation code Z80 and 
recovery of memory. 



                           CONCLUSION


    Acceleration is adequate for the speed of
VIDEO INT for up to 61-62 thousand in "RAM TEST'u" and for the 
upper memory to 78 thousand. On this basis there is reason to 
believe that accelerated in the same way the computer with the 
general field of memory speeds surpass "PENTAGON 
48/128/512/1024" on the value of the order of 10,000 cycles, 
which agree quite well. Unless of course, considering that he, 
in turn, was not accelerated ... 


    That's all. If you have any questions, please call me on 
the phone in Gomel (0232) 97-13-69 (preferably closer to 
22:00), ask Paul or write to: Belarus, 246901 Gomel, yn 
Kostyukovka, October-11 / 9, Primachevu Pavel Alexandrovich, or 
refer directly to the editor "Polesie".