Speccy #07 31 декабря 1996

Концепции     Железо

idea - How to be videokontroleru ZX-SPECTRUM'a.

             IDEA


 A lot of publications have recently been devoted to the 
transition to other types of computers.


 The main reason for dissatisfaction
users ZX-Spectrum - a
its low graphics capabilities.

 Though a small screen and memory
has its advantages (it can be
make programs with good dynamics are not as fast
O most modern
computers), but still would like to see, and normal multicolor 
screen, not boring all squares.


 Programmers truth in this
to make miracles. Many
probably already looked at
Spectrum'e multicolor, multipixel
and various images on the curb ekrna. But all these effects
impose many restrictions on
program, also because of varying duration signal
INT on different computers all
it looks differently.

 We represent your attention
Article Strelnikova from Andrew
City Millerovo Rostov region in which the author expresses some 
very interesting ideas about the development of the video 
controller for Spectrum'a. 

 To realize this project in
life requires, of course, the efforts
electronics and, of course, programmers. I would like to hear
their views and proposals on the affected subject.

 I'd love to hear readers' opinions on whether
creation of this unit.

(C) Strelnikov AS


 Recently, more and more
talk about the need to expand SPECTRUMa. Often encouraged to 
develop new model SPECCY, which includes

New hardware gadgets.
However, the price of such machines, the potential volume of 
production, as well same number of users who have

willing and able to buy a new computer will not allow new
model widely adopted. More promising
path - the improvement of existing models SPECTRUM-compatible 
PCs. Creation of expansion units that attach to computer with 
minimal interference in the scheme. 

 Most of hype around
hard disk controller and
soundcards. But I would
draw your attention to
schedule. Because 90% of information we
get through zrenie.A schedule
our SPECCY leaves much to be
desired. Many of the household
machines that have emerged in our country
in the late 80's superior
SPECTRUM quality graphics.

 Of course, there have SPECCY and their
pluses, but what's good for the 1982
years, to the late 90's no longer enough. SPECTRUMu need a new
ekrana.A controller for that
he gave the maximum number of users, you must
discussion of the project on the pages
some magazine (or better
few).

 I chose "SPECCY", because
He, in my opinion, is closer to
people "than its capital
counterparts.

 I'll try to articulate how
the same should be the new video controller SPECTRUMa, which I
would not spare the money.
 Firstly compatibility. He should maintain a normal screen
SPECCY without peretykaniya connectors.

 Several modes of resolution,
until VGA.I do not say that the graphics are at a higher
resolution will be
slow. Will suffer
only shooters and arcade games.
A adventyurnye, RPG, strategic, economic, logical,
traditional stand to benefit,
if the screen will be placed
more information. I'm not talking about systemnyh and applied
programs, where fast graphics
practically is not necessary.

 It is advisable to screen modes
to switch software, in
process. Then the program
can use several
different screens. Imagine: in
UFO-2 movie - 320h200 256
color map of the world - 512h256 8
colors, battle with the UFO-256h192 256
colors, fighting with inoplanetyanami384h256 16 colors, the 
encyclopedia ufologist 640x200 text, illustrations - 320 x 200 
256 colors. How you can improve design software! 
High-resolution graphics will be used to display text and 
illustrations, and for dynamic episodes can include more

low resolution. For dynamic graphics can provide screen mode, 
like used in game consoles, ie purely symbolic

(Sprite).

 Estimate the size needed
screen memory table will help.
s
 In the table vertically - possible resolution, horizontally - 
how the color coding and number of colors.


 1-monochrome, 1bit per pixel
2 colors.

 2-in SPECTRUMe, byte attribute to familiarity, in 16 colors
familiarity.

 3-byte attributes for the strips in
8 pixels. As a TIMEX or
ORION-128.

 4.3 bits per pixel, 8 colors
for each point. At the resolution
256h192 screen size-18K is in
2.6 times more than the standard.
And at a clock frequency of 7-10MHz
graphic work will be the same
fast as a standard screen.

 5-16 colors for each point, 4
bits per pixel.

 6-256 Flowers for every point, 1
bytes per pixel.

 7, using 4 bits per pixel
(Method 5) for each of familiarity
allocates 1 byte of storage
Rooms palette and obtain
16 * 256 = 4096 colors, ie, in one
familiarity can be used
16 colors, but on the whole screen
may be all of 4096!

 8-the same way for 6. Bytes
palette to give familiarity
256 * 256 = 65536 colors!

 As seen from the table, you can
get very good results, without going beyond 64K
pamati screen.

 Memory controller must be
64K of RAM (one line RU5), for
subsequent expansion it is required to provide a place for the 
second line of RU5 and follow them replacement on RU7, although 
you can restrict, and one line of RU5, and then replace them 
with RU7. (Incidentally, the computer ENTERPRISE-128

Z80 processor and a clock
frequency 4MHZ has 64K on-screen
memory)

 As the processor must
Z80H used with a clock
frequency of 7-10 MHz for ROMs, I think
enough for 27,512 (64K).

 ROM is better to use as
ROM-drive, it will easily
change the size of memory for the screen and
administering the program.

 When you turn from the ROM-disk boot BIOS, which supports the 
standard SPECTRUM ovsky screen (in this mode, you can improve 
the compatibility at the expense of more emulation ULA: 312 rows

frame uroven black, a correct signal INT and
etc.), and admission team
the inclusion of a new display mode loads and executes its 
corresponding program.


 It is also necessary to provide
the ability to download programs
from the ground will OZU.Eto
programmers to create their own
new screen modes.

 In addition to management functions, programs should include 
procedures to facilitate work with grafikoy.V first is the 
calculation addresses in the on-screen memory. Your

program has to deal with the coordinates of pixels, and the 
calculation of addresses is performed in the controller. Not 
prevent the same procedure works with sprites, the construction 
graphic primitives (lines, rectangles, circles), work with 
vector graphics. So as is the ability to download

their programs, then you can leave the control part of the 
program, and supporting procedures to write in their own way.


 Modes supported by the ROM,
should be available from BASICa.

 What modes are supported in
ROM, you need to discuss, but I
suggested the following:

 256h192 color coding -
- 2,3,4,5 and 6 (see table)

320h200 2,4,5 and 6
384h256 2.4 and 5
512h256 2 and 4
512x384 2
640x200 2.4 and 5

 Regular television shows well in resolving 512h256.Pri
higher resolution boundary pixels will be blurred, images from
This can only benefit (not
will be visible to their point structure), the text will also 
be well differences, especially if the matrix

character will be more than 8x8.

 The most convenient way to connect - similar muz.soprotsessoru.

 Controller card is inserted into the
panel of the processor and the processor
installed in kontroller.No
may not like the owners of vehicles with the system bus, but
and the rest need to think about where
muz.protsessor stick. Better
whatever the controller had the connector,
similar SCORPIONu, and for
those with the system size sockets
No, complete with controller
should go to pay the connection.
It is inserted into the panel protsessora.Na this board is
processor muz.soprotsessor or
connector to install it (preferably on a separate display
connector ports muses. coprocessor)
buffer components and output
connector. This razemu train
connected controller, or
fee - expander. This fee
contains several slots to
one of them and connected
controller. Thus facilitated the further expansion
computer.

 P.S. When I was preparing an article for
dispatch and learned that Baimakov
Jaroslav did videocontroller
based on the Z80 with a resolution
320h200 256 colors. The same is almost
what you need. Is the basis,
which can be improved.
Although I would not of such
refused.

 Text typed in assembler
ZX-ASM v3.0


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