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zы(C) Ryazanov M.A.
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I want to share with you my thoughts
niyami about ZX-Spectrum. Thoughts about his perfection
I haven’t been given peace of mind for a long time, and now
two articles Andrey Ovsyannikov - "Reserves
ZX-Spectrum"and "Reserves #2" in Deja Vu #07
and #08 accordingly, as they say, "za-
they dropped the most secret things,” for which he was angry
thanks a lot! In this article I have combined
ideasAndrey Ovsyannikov and his thoughts
regarding the new generation ZX, exactly
wow, because the "all in one" principle is doomed.
Well, now, in order...
1. Because. the heart of the ZX is the Z80, so
let's start with it. Personally, I think that the
running the Z80 as a CPU is somewhat impractical
but because of the probablelack of resources Z80
with increasing "powers and speeds".
Therefore, it is advisable to replace it with another one,
moreover, 16-bit, for example, 8088 or
even 80386. However, although they are with
Z80 compatible, you will still have to deep-
sideways change the architecture of the ZX computer,
organize -5V (for some models),
and still some loss of co-
capacity with a real ZX-Spectrum. More
It would be practical to replace the Z80 with 2xZ80A(B).
The main problem when connected in parallel
two Z80 consists of combining pins D0-
-D7 and A0-A15. Merge them (D0-D7 first
CPU with D0-D7 second and, accordingly, A0-
-A15 of the first CPU and A0-A15 of the second) in one
real binary bus (data and address)
in practice it is very difficult, and it is unlikely
will do without another CPU, and use it
callingnot acceptable due to decreased production
driving ability. Therefore, I suggest using
call two processors together, and,
each of them operates from one master
generator, but perform actions autonomously
(different or identical) according to one program
frame that will support both Z80
CPU and will be the operating system
your computer. Of course, somehow I will need
It is possible to change the interrupt system, signals
system management, etc.
2. Bus. It’s not bad to make it like IBM
ISA is a very good solution, even one
named signals available in ISA and ZX-
-Spectrum, let them be located in the same
in the same order on the slot that can be
also used as in IBM PC. However,
it should be ensured that peripheral
the device will use both processes
sora. It would be nice to buffer it quickly -
acting buffer on the series K1531 for
radiation of high load capacity.
3. RAM. RAM distribution is somewhat un-
regular: old RAM 128Kb, 256Kb or 512Kb
will be used as a mandatory system
dark for storing resident programs and
etc. In addition, it should only work with
with one processor (it won’t be able to simply
yeswork with two CPUs). Another part
RAM is almost completely USER, for
with the exception of the new screen area, about which
the swarm will be discussed below. Mandatory
there must be ROM (system memory), cache memory and,
maybe BIOS.
As USER RAM you can use
call (and preferably) RAM boards from IBM PC,
because they are low cost,
and many people already know the connection.
4. New video mode. Actually, the theme
new video mode is a separate topic, but I
I'll try to briefly talk about my ideas
about this. First of all, video memory
will be located in USER's RAM, in his
beginning (0H), and the whole thing will take up 1MB
(cell - 16 bits). Per pixel
one 16-bit cell is allocated. In
depending on the expansion, it can accommodate
several or one screen area
lust. According to my calculations, to begin with,
it would be bad to expand 512x384 pixels
at 65536 colors. Organize a cell pa-
I suggest this:
8 primary colors x 8192 shades = 65536
colors for each pixel! Of course, if
someone will suggest a more efficient distributiondivision - it will undoubtedly be accepted.
The operation of the controller with Video RAM should be
change to sequential polling of each
cells depending on the address - this will be
easier to implement in practice and program
It will be more convenient for mystics to work with the screen.
By changing the step of writing a binary number in
D4(1)-D0(2) you can, if necessary, reduce
choose the number of flowers. With such an organization
Video RAM RAM polling rate at standard
In this method (during an interruption) there will be a
set 9.830.400 Hz, which is acceptable for
most foreign RAM chips and non-
which are domestic.
5. SOUND. Recipe for "smart" sound
map Ovsyannikov Andrey,in my opinion,
very lucky, I'll just add some
changes to the idea. SOUND CARD will be available
establish itself as a separate independent
computer on Z80 (for example, "Leningrad 2")
+ 4 DACs (Covox, Soundrive, GS) + 2(4) ADCs+
+ RAM (preferably more) + AY8910. EU-
Should I use Leningrad 2 as a basis, then
the interruption period can be reduced if desired
sew (TV will no longer be needed) so that
there is time left to change the state of the system
dark variable FRAMES,which can
needed when changing Sound tracks. Except
Moreover, by reducing the interruption period
computer performance will increase
(SOUND) and hence the sampling rate
in the DAC and ADC, and with it the quality of the
produced and recorded music. Expand
RAM in the SOUND CARD will most likely be used up
will achieve for known reasons. It should be like this -
install one AY on the main board,
which should only work with one
(with two more difficult) CPU. This is done to
go, so that, for example, in a game program
SOUND CARD will play the accompanying mu-
language, and AY, installed on the main platform
those will play sound effects.
Interface SOUND CARD with the main board
will be the connection to the internal S.C. bus. to
main system backbone through buffers
with Z-state, control switching
possible through a regular port. Such pairing
done in order to maximize
You can, of course, change the data exchange rate
but do it as Ovsyannikov An- suggests
drey, through ports. In ROM S.C. can you pro-
sew a special program with a variety of
mi Sound FX'ami. Using the RAP also
will increase the speed of rewriting information more
mation between S.C. and the main computer,
This mode is provided in the Z80.
6. FDD and HDD.Usagetwo CPUs and
independent S.C. will do the job on this
computer more pleasant, because as long as it lasts
the rest of the program is loaded,
the user will be able to work with
loaded part (of the program) and listen
pleasant music, like on an IBM PC. For more
radical improvement of FDD and HDD
did not take up the problem of not having the proper amount
wa information about their work.
7. The rest. Devices such as, on-
example, Kempston, Kempston Mouse, Keyboard
can be placed on a separate board,
and on the main one, because suddenly it will be necessary to change
take software. It’s good to implement internal
modem, as an expansion card or connection card
dressing up with the outside.
Of course, all this is around the bush, poet-
I want this issue to be addressed
greater minds than me and, preferably, bearing
how many companies, such as: "NEMO", "Scorpion".
A little about the standards. I offer in ka-
quality slots for expansion cards are used
call standard IBM ones, get them
not difficult, and on expansion boards it’s not possible to
it is necessary to install special connectors
we. In addition, the assignment of pins to connectors
emah can be left as it is
on PC players, then any mortal with the same
can find out what-where in any matter
a reference book on hardware for the IBM PC. I would likeso that those who take up this issue will
exchanged information with each other, and with
by an ordinary user via electronic ma-
gazins, letters, etc.
If you are interested in this article, then
write to:
310085 Ukraine, Kharkov,
Academician Proskur St., 9 "B"-4
Ryazanov M.A.
P.S. Look for the diagram in the application! The file name is
is: "cxema_NS".
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