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Speccy from the inside.
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(c) VTS'99
I was asked to talk about the mouth
growth and work of the Spectrum. At least from me
The teacher is worse than ever, I’ll try, sir. In general,
this request was actually the first reaction
for the cycle "Iron for Beginners". This about
communication is needed so that I know
what you need to write about, because you yourself
it is quite difficult to determine (when
you know it all ;)
So, let's sketch out the Speccy block diagram.
┌─────┐ ┌─────┐ ┌────┐
│ ROM │ │ RAM ├──┤ VK ├───< TV-set
└──╥──┘ └──╥──┘ └────┘
┌───┐ ║ ║
│ │ ША (16 bits) ║ ║ │ ╞═════════════╗ ║ ║ внешние
│CPU│ ШД (8 бит) ║ ║ ║ устройства
│Z80╞═════════════╬════╝════╦═══╩═════════╦════ . . .
│ │ ШУ ║ ║ ║
│ ╞═════════════╝ ┌─────╨────┐ ║
└───┘ │ блок │ ║
┌────────────┬──┤управления├─┬──────║───────┐
│ │ └──────────┘ │ ║ │
┌─────┴─────┐ ┌───┴──────┐ ┌────┴────┐ ║ ┌─────┴──────┐
│клавиатура,│ │магнитофон│ │бипер, AY│ ║ │ порты │
│ джойстики │ └──────────┘ └─────────┘ ║ │конфигурации│
└───────────┘ ║ └────────────┘
║
┌─────────────╨──────────┐
дисководы >─────┼ Beta Disk │
│ (контроллер дисковода) │
└────────────────────────┘
Вообще говоря, Beta disk можно отнести
к внешним устройствам. Однако в некоторых
компьютерах он расположен прямо на плате,
и в настоящее время является фактически
системным устройтвом.
Архитектура Спектрума является класси-
ческой, т.е. наиболее простой и понятной.
В основе лежит центральный процессор (CPU
-Central Processor Unit) Z80. This pro-
the processor was built on the basis of the i8080, one
to a more thoughtful concept and architectural
tour Z80 made it possible to significantly simplify
Speccy circuit design.
The processor has8-bit (byte) bus
well data (SD), i.e. sampling data from pa-
denting occurs sequentially. Absent-
There are also all kinds of pipelines and caches, and
memory for programs and data is combined,
i.e. Z80 - classic von-neumon
processor.
A distinctive feature of the Z80 is
also a very rich command system,
which makes him stand out as a typical representative
body of the family CISC processors (in contrast
from the RISC family, which has very meager
time-optimized command system
neither; presumably this family has
higher performance). This
property turns out to be very useful in a number of
cases, because gives increased co-density
yes (i.e. saving memory), increasing performance
performance and programmability
directly in assembler without special support
lies. Moreover, the command system is saturated in
within reasonable limits, optimal for 8-bit
no data bus (8-bit operation code -
KOP'a).
Address bus width (АА) - 16 bits
(2 bytes), which allows simultaneous ad-
Resume 64 KB of memory. To expand pa-
they use special “windows” on which
which project different "pages"
extended memory. To control the extended
Configuration ports are used for memory
walkie-talkies.
Via the address bus, the processor sets the following:
same port address (external to
device), i.e. theoretically he can
Can access 65536 ports. In practice
such a quantity is not needed, and use
there are simpler (circuitry) mechanical
port addressing nisms.
Control bus (CB) represents
itself a set of control signals, with
with which the processor controls the system
mine (e.g. memory access), as well as
receives additional information (eg.
interrupt request).
The three tires described are necessary
and a sufficient minimum for organizing a small business
(microprocessor)systems (so-called "three-
bus architecture") and in the general case
are called the processor bus. They can come to her
be connected to external expansion devices
rhenium (modem, GS, etc.).
Memory is not shared by the processor,
however, physically it can be permanent
(ROM - read-only memory,
ROM - read only memory),information included
which is stored regardless of the presence of pi-
melting tension, and maybe from there only
read; and operational (RAM - operational
memory device, RAM - random ac-
cess memory), information in which is stored
only in the presence of supply voltage
marriage.
ROM stores the program that runs
when you turn on (or reset) your computer. B
The Spectrum interpreter is stored here
BASIC and TR-DOS.
Programs and data are loaded into RAM
user who work and process
are processed by the processor.
In addition, there is anothertype of memory -
external (discs, cassettes...). She uses
suitable for storage and physical transfer
large amounts of information, and maybe
very diverse. However, in relation to
to the processor it is an external device
yours and interfaces with its bus using
controller (eg Beta Disk). Directly
The processor cannot directly operate with it.
yes, i.e. necessary information first
loaded into RAM and then processed.
To form an image on the screen
TV special memory is allocated in the RAM
memory area - screen area. Into it
the processor records information that
then displayed by video controller (VK)
on the TV screen. The operating principle of the VK is based on
line-by-line (synchronously with TV scanning)
reading information from the screen area and
converting it into a TV signal, perceiving
read and displayed by the TV.
The control unit (CU) is
address decoders, ports and interfacing circuits
communication with system devices is necessary -
mi for its functioning in the minimum
configurations.
Portsconfigurationsnecessary for
management of internal computer resources,
e.g. extended memory, turbo mode
etc.
to be continued...
Well, that's enough for now. There will be more
Each computer block is examined in detail
separately.
And if anyone doesn’t understand something, drop me a line
a couple of lines... ;-)
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