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".
