(C), Mikhail Smirnov (CLEAR) Rybinsk
PART II
(Continued)
Now we go again about the sound and
not only that. (Brad as nonsense - nothing special).
Ideal computers and there never
there will be no glitches are everywhere, with the only
difference is that some of their more than
others. (Gluck - code, or hardware
nedoglyad developers.)
Constant disputes adherents Amiga and
PC to read, of course, very interesting, but
world of computers is much wider, so I
talk about almost unknown in Russia and
CIS computer, ranked second in the
the world in prevalence after the PC -
Apple Macintosh. (Apple has managed to
80 score Macs entire system of "popular" education dollars -
from kindergartens to universities). I hasten to note - I did
not call home to buy the Mac, so as it will be very irrational
(in CIS).
The history of creating the first computer
Apple's a bit like a story
Amiga is a story of ups and downs, not
cease, and to this day.
Everything started with the "garage", two other
Steve Jobs and Steve Wozniak, learned of the output
in light of a new microprocessor firms
Motorola, decided to create a computer game on one card (up to
this point they both were fascinated by electronics,
In addition Wozniak worked in the firm
"Hewlett Packard", and Jobs in the firm
"Atari"). They planned to distribute it among the members of
the computer club "Home Brew Computer Club", they have also
previously organized. On the development took about six months,
ready to board was then placed in a wooden cabinet. Computer
show the newly attributed to the owner of the local computer
store, who was a member of the club. He ultimately offer Steve
the deal: they make 50 per month computers, and he pays them in
cash on fact.
Then it's time to come up with the name of his firm.
Charter sort out intricate variations Jobs jokingly suggested
"apple" (apple). Quite unexpectedly, a word like both, and it
they stopped. April 1, 1976, they established firm Apple.
Evenings and weekends Stiva continued to work on your
order. Exactly on time, they put 50 computers at the price of
an Apple 666 dollars 66 cents. Satanic number
caused a firestorm of local communities, members and customers
- the price had to change.
Cases began to go uphill. Millionaire
Markulla invested in the company U.S. $ 250,000 and began to do
business, providing Wozniak and Jobs freedom of creativity. The
company's turnover in a short time was millions of dollars, and
employs hundreds of workers and employees.
In 1979 (3 years), the situation
began to deteriorate - the computer market
PC came from the "Big Blue"
(IBM). We had to do something.
Jobs together a team of talented engineers (some were from the
"Xerox") and began work on a project called
"Mac." This project was completely
independent of the computers under the name
Apple (which continued to be issued).
Jobs did not suit IBM - this configuration, operating system,
PRO-DOS and other things. According to his plan to a new
computer, everything had to be built otherwise.
At that time, Apple was carried out three projects:
Macintosh, Golden Delicious and Pippin - all named for the
varieties of apples. The name "Macintosh" picked up engineer
Jef Raskin, who, like many Americans suffered spelling - grade
Apples was written "Mcintosh". But the bug fix did not.
That is such a curiosity owed his
name of a newborn computer that uses no text, and graphical
user interface. It was a real revolution in computer technology.
The official birth year, "McIntosh"
- 1984 th. Firstborn name or Macintosh XL
Lisa. He had 3, 5 "floppy drive, 9" monochrome monitor, mouse,
and a very modest current concepts of memory.
Since then, "Poppy" fully grown, grown up and become
indispensable artists, publishers, and all those who are not so
it is important to delve into your computer
engaged in it my favorite thing.
To date, Macintosh is the only real alternative to the PC.
With the release of "Windows 95" PC users are hoping that their
heartthrob will be equivalent to the Mac. What in really?
In the world of IBM PC - compatible computer computers
themselves and their software is usually developed different
firms. Therefore, comparing with PC Windows and Macs, compare
features installed on them operating systems. However, since
used the whole complex - the computer and
OS, such an approach is not quite right. When buying a Mac user
receives an integrated system in which software is closely
associated with hardware. Clearly, in the case the PC is not
so. Recently I read in Computerworld: "Many of the features
InDesing (new publishing program)
were shown how to
Macintosh, and in Windows. However, in
Progress Windows - version of the system error message is a
memory that the audience responded with laughter and applause. "
A friend of mine recently visited
Switzerland, where he talked with the local network
administrator in some school (50 and 9, Mac PC), so he
complained that he had to tinker mainly pisyukami and to Macs,
he almost did not fits.
The main advantages of Macs
as they were, and remain easy to use, the possibility of
multimedia applications, the lack of compatibility problems.
Despite the significant steps
Microsoft's "ochelovechevaniyu" interface
new operating systems, Apple remains
leader in this field. If we are talking about
ease of use of computers in general,
then Apple benefits from the operating system. Given that the
development graphical user interface (GUI) in the Apple
started long before similar studies for the PC, the company was
able for it Time to go far in front. McIntosh to
So far easier to use, especially if
we are talking about the integration of computers into a local
network or configure them.
Macs, as long isolated part of the computer business,
today are the most "compatible"
computers. In this area, Apple has made great advances, and
overcome the gap between Macs and PC. Today, Macs can not
only read and write PC - floppy disk drives CD-ROM, but also to
perform Dos and Windows application. To this end, various
Windows - emulators, one of the most last - Virtual PC (fully
emulates Pentium MMX). In turn, the PC also have a Mac
emulator. How it works under these emulators - a separate
conversation, may require a separate article. Briefly what he
saw himself: Virtual PC on Power Computing 225 MHz (clone Mac,
Power PC processor 604) emulates Pentium 90 (Frequency
Processor), video works almost two times slower; on a G3 350
MHz - Pentium 166 MMX with no brakes. Basilisk on the Pentium
166 MMX, overclocked to 187 MHz emulates 68020 1 MHz! :) (This
is not a joke)
I do not think that the emulator was written specifically
for Mac BASIC and an emulator PC assembler (though who knows:)).
In the early 90's, Apple again
there were problems due to poor management of the company (by
this time the founders of Company Steve Wozniak and Steve Jobs
went out of Apple and doing his own projects), anyone who feels
like she began to prophesy ambulance death and withdrawal from
the market of personal computers. Apple grabbed the "straw" in
the idea of creating a RISC processor, the basic concept of
which were laid in the mid 80's, and together
with IBM and Motorola have released a new processor PowerPC.
Almost immediately, along with the announcement of the PowerPC
Apple unveiled a new computer on the basis of their "Power
Mac". PowerPC processor was in some way
response to Intel 'y on the Pentium MMX, and after
Released Pentium II was presented to PowerPC
G3. These steps, though correct the situation,
but before the crisis was far away.
In general, the struggle for markets between Apple and
IBM is a struggle not so much between platforms as a whole (if
we take the technical side, but not marketing), but among the
processors. Intel, as the leader, stepping on the technological
and architectural progress, collect all the "bumps, banks,
running track, "wound on the condition and make
not too shabby masterpieces, struggling not for long
forward.
After leaving in 1971, a landmark
Intel 4004, this trend is seen
the naked eye. Many firms found that the production of
processors brings good dividends and have rushed to sculpt the
"stones". Someone walked in the footsteps of Intel, someone
went his own way, but the majority created their creations (at
equal - the data bus and frequency) is much better than the
leader. Example Z80 and 6800 more productive than the i8080.
It was not in the frequency and bit rate, and in
internal architecture of the processor: 6800
had only two general register
(Both can operate simultaneously as batteries), using 3 cycles
for the read-write when addressing memory.
In this race, Motorola, barely kept pace with the leader
(given only to certain processors): 8080 - 6800, 8086 - 68000,
80286 - 68020, 80386 - 68030, 80486 - 68040, Pentium - 68060,
Pentium - Pro PowerPC, Pentium II - PowerPC G3.
About the Pentium III, it is not a new processor (in the usual
sense, the new processor on the old software on the same
frequency The results are faster), this Pentium II
with the addition of several new commands for
work with the Internet, and more appropriate to be
had called his type - "Pentium II +". But in
a situation where competitors come on
heels, incomes fall takes a bit
zapudrit people brains (Marketing:)) and
corrected it - the crowd pushes US users outdated Pentium II at
the far shelf, and run to the store to buy
"Modern Pentium III".
Now for the G3 - a full 64-bit
processor (with Intel Mersed still in draft)
5 pipelines, 2 of them for floating-point data, the L2 cache at
least 512 KB.
In September, appeared G4, and on its
based Power Mac G4, which provides
performance of more than 1 billion floating point operations
per second (peak performance of the PowerPC G4 reaches 4
billion in the second). A distinctive feature of the new
processor is embedded SIMD-module (under named Velocity
Engine), allowing high speed parallel processing of vector data
and has additional 162 processor instructions registers and 32
bit depth of 128 bits. When using a set of tests developed by
Intel to demonstrate CPU speed Pentium III, PowerPC processor
G4/500MGts was on average 2, 94 times faster Pentium processor
III/600 MHz. When comparing the performance of the program SETI
@ Home (the project the search for extraterrestrial
intelligence) PowerPC G4/500 MHz processed within 6 hours of
such a wealth of information, which is a Pentium III 600 MHz
processed within 25 hours. For more information, please visit:
http://www.apple.com/powermac/
processor.html.
The lag in release processor models Apple neustraivalo in
order to end with this and was formed an alliance with Motorola
and IBM in the early 90's. Although 68060 was
more productive Pentium 'A marketing ploy Intel' a - refusal to
use digital system in the designation of its new processors
nullified all attempts competitor to earn good money from
increase in sales of Apple Macintosh. At the
while the ratio of processors
the desktop was about 1: 10 in
favor of Intel. Fading rate induce sales of Macs Motorola fewer
invest in developing the next generation of processors 680h0.
Apple, experiencing another crisis, needed a miracle and a
miracle in the form of alliance has brought not only financial
investments but also intellectual and technological,
represented by IBM.
In 1993 he appeared PowerPC, which has within RISC -
architecture (reduced instruction set) emulation commands 680h0
just software, in contrast to Pentium, which is only partially
RISC - 80h86 hardware emulation commands
(Intel, burdened with compatibility, not
could afford such experiments).
Pentium Pro was already a pure RISC, but for
Compatibility with previous generations
Number of processors crammed with such
logic, that its production has now become almost unprofitable.
Apple, jumping on the PowerPC,
not particularly think about the consequences, to choose
it was not anything else - "sink or swim." Download 680h0
worked the brakes, and popular programs had to re-
recompile under PowerPC. New versions of the programs began to
emerge with two installations for 680h0 and PowerPC
The first processors PowerPC (601, 602,
603, 603e) inferior in performance
similar to Intel, and only the PowerPC 604
were able to beat them, with the advantage
was hardly significant.
Along with the PowerPC 604 was released first samples of a
64-bit PowerPC processors 620, which has doubled more
transistors than the 604-th. It was the biggest disappointment
- superior Pentium Pro was not More than 10%, so in the next
PowerPC 750 changed the microarchitecture, and obozvali
PowerPC G3 (Generation 3 - CPU
Third generation).
Simply using a PowerPC G3 at
Macs are not allowed to significantly increase
sale. At this point, Apple's back
(After the failure of "epic" with a computer
"Future" - NeXT) one of the "founding fathers" - Steve Jobs.
Under his strict guidance Apple has taken the path changes
design of computers (both external and internal).
Almost a year ago the world was surprised by the new
development of Apple - iMac, especially designed for home
entertainment and Work on the Internet. System unit
iMac 'and is combined with a monitor (candy bar)
and the dimensions of "monitor" from this almost
not increased, body translucent -
shows that under it, no 3, 5-th
drive (seen in the states he no longer needed
- Wherever tkni, around Internet). Since January 1999, iMac
'and come in packages of five different colors:
- Blueberries
- Lime
- Strawberries
- Mandarin
- Grapes
Now in more detail (May, 1999
city):
PowerPC G3 333 MHz Cache 512Kbayt
(Backside L2) system bus 66-MHz cache
Tier 64Kbayt 32Mbayt RAM expandable to 384 MB Memory Bus 64-bit
Internal hard drive 6Gbayt
CD-ROM 24-x
2 USB ports for connecting up to 127
peripheral USB devices to each rate of interaction with devices
12Mbps
Built-in 10/100BASE-T Ethernet Modem 56-K, supporting the
K56flex standard and V. 90
Display: - Type of multiple-scan, the tube
shadow mask: 15 ", the size of 0, 28 -
6Mbayt video memory - Refresh
up to 117 Hz
Video: - Built-chip ATI RAGE PRO
Turbo 3D akselleratsiey with 2D/3D graphics
Two built-in speaker with support
The SRS Integrated microphone connectors
input / output
Keyboard Apple USB: - Change
angle of the keyboard - Works well
as a USB hub
Apple USB Mouse
Height: 39, 5 cm with stand
Width: 38 cm
Depth: 44 cm
Weight: 17, 3 kg
Display mode
Mode Frequency maximum resolution of 640x480 117 Hz,
24-bit, millions of colors 800x600 95 Hz, 24-bit, millions of
colors 1, 024x768 75 Hz, 24-bit, millions of colors
The reaction to the emergence of iMac in the U.S.:
"IMac - it's Christmas in August! -
said Paul Ramirez, vice president of
Marketing ComputerWare. "We sold over
One Saturday iMac computers more than
All desktop PC in July. "
"IMac 'and sold the majority of our dealers this weekend,"
- said Steve Jobs (temporary manager (CEO)
Apple). "Until next week we will launch in stores, tens of
thousands iMac 's. "
"IMac might be one of the most
selling models at all times. When
the sales process goes, may be sold
several million cars, "- says
Roger Kay, an analyst at IDC. Jim Helpin,
executive director of chain stores
CompUSA, said that sales of iMac will
in history. "If this weekend we'll sell all the computers that
we have it will be the best-selling iMac computer, which we
have ever seen. "
Representatives of the chain stores MacMall
say they can not meet
all orders. "We sold 1,200 units. Only
this morning, "- said one of the managers
Sales MacMall.
In the less than five months, iMac became
best-selling computer in the U.S., it was
sold 800 thousand units (more than
PC). About 55% of users are
adherents of the old Mac, 32%
first purchased a computer and 13% - the former users of
"normal" PC.
In Moscow, iMac 266 costs about $ 1250,
iMac 333 - 1450 $.
According to the test BYTEmark iMac 266
half times faster than Pentium II 450MHz,
and two times than the Celeron 333MHz.
In early 1999, Apple released
new Mac for the professional market - Power Mac G3, the amazing
buildings - a transparent plastic saturated blue and
milky-white flowers, combined with faired.
Inside:
PowerPC G3 processor with a clock frequency of 300 -, 350
- or 400-MHz, 512 KB or 1 MB cache second level, type
backside, on the processor module with a frequency of 150 -,
175 - or 200 MHz respectively depending on the speed of the
processor system bus is 100 MHz Integrated co-processor for
floating point operations, and 64K processor cache, the first
level (32K for data and 32KB for instructions)
64 MB or 128 MB of RAM
Four types of PC100 SDRAM memory expansion slot
DIMM, supporting up to 1GB of memory type
PC100 SDRAM, with the following
DIMM'ov: 32MB, 64 MB or 128 MB (64-bit
64-bit technology) 128 MB or 256 MB
(64-bit, 128-bit technology)
Drives:
6GB hard drive or 12GB Ultra ATA or
9GB Ultra2 LVD SCSI card with Ultra2
LVD SCSI PCI 24-speed (maximum)
CD-ROM or 5-speed (maximum)
DVD-ROM with DVD-Video playback (reads CD-ROMs at 35) Zip-drive
(some configurations) Place two additional Ultra ATA, UltraWide
SCSI or Ultra2LVD SCSI drives
Two FireWire 400 Mb / s
Two-port 12-Mbps Universal Serial Bus
(USB)
Port Apple Desktop Bus (ADB)
Built-in Ethernet 10BASE-T/100BASE-TX
(RJ-45)
Additionally possible to install an internal modem 56K
(supports K56flex standards and V. 90)
Four slots PCI: three 64-bit slots
frequency of 33 MHz and one 32-bit slot
with a frequency of 66 MHz allocated to
Graphics Card: ATI RAGE 128
15-pin mini D-Sub VGA connector and
Macintosh-VGA adapter
Minijack input / output 16-bit
stereo, with a frequency of 44. 1 kHz
Built-in speaker
Graphics Card ATI RAGE 128
16MB memory SDRAM, providing
following features:
2D acceleration
128-bit internal accelerator
Hardware accelerator graphics and video
Supports resolutions up to 1.920 x
1.200 pixels at 32 bits per pixel
(Millions of colors)
3D acceleration
Advanced integrated aksellerator
Single-pass processing multitexture
Full 32-bit per pixel (b / n) Z buffer
and 8-b / n "stencil" buffer
Sustained support QuickDraw 3D RAVE and
OpenGL
Keyboard Apple USB Keyboard and Mouse
Apple USB Mouse
Power consumption (without monitor): 200W
Height: 43, 2 cm
Width: 22, 6 cm
Depth: 46, 7 cm
Weight: 13, 0 kg
In tests BYTEmark computers
PowerPC G3/400 more than twice
faster computers Compaq Deskpro
Pentium II/450.
To gain access to the connectors
extensions, pull the ring
on the side wall of the housing and open it -
all the boards are mounted directly on it. As
and IMac 's no floppy drive and
support SCSI. To use SCSI -
devices necessary to establish an appropriate fee in one of the
connectors PCI.
For lovers of Notebook'ov Apple releases Powerbook:
elegantly rounded shape, translucent orange-molochnobely
housing.
Each model comes with two
built-in expansion slots (which
can also be used as slots
batteries), including two slots PC
Card.
Inside: 233, 266, or 300 MHz
PowerPC G3 processor, 1MB backside level
2 cache at 266 and 300 MHz processor module, 125 or 146 MHz
64-bit backside-bus, 66 or 83 MHz system
Bus. Integrated module for floating point and cache 64K level 1
on-chip (32K data and 32K instruction) or 32MB
64MB RAM; 2 x SO-DIMM, support
Up to 192 MB memory, 4MB ROM.
Internal 2GB, 4GB, or 8GB IDE
Winchester, 2 expansion slots 3. 5 "
CD-ROM or DVD-ROM and other devices
Removable storage drive 3.
5 "1. 44MB memory expansion slot for 20-speed (maximum) CD-ROM
for expansion slots
Port Apple Desktop Bus (ADB)
-SCSI-port is not less than seven
peripherals
-Serial (RS-422) port
Port Power Adapter
Built-in 10BASE-T connector
Ethernet (10 Mbps)
Modem RJ-11 port supports
K56flex modem
Infrared-(4-Mbps IrDA)
-PC Card slot for two Type II PC
Cards or one Type III PC Card or
CardBus cards
-S-video output connector
-24-bit video out connector port (VGA-style connector)
Sound:
-16-bit CD-quality stereo input /
output
Video:
2MB, 4MB SGRAM, or VRAM supports millions of colors on
external monitors up to 20 inches
-2D/3D Graphics via an integrated video controller
-Support for Zoomed Video
in the lower PC Card slot
Display:
-14. 1-inch (diagonal) built-in display TFT XGA
active-matrix supports millions of colors at
resolution 1, 024h768 pixels
Two built-in stereo speakers
Battery: 49 Watt / hour lithium-ion.
Average life: up to 3. 5 hours on one battery, up to 7 hours on
two batteries under normal use
Built-in full-size keyboard
76 (US) or 77 (ISO) keys,
including 12 function keys
Apple track pad
Depth: 26. 4 cm
Width: 32. 3 cm
Height: 5. 1 cm;
5. 3 cm to 14. 1-inch
Model Weight (depending on configuration);
computer with a modem, battery and CD-ROM
weighs 3, 5 kg
At this while you can and finish the story about the
history of Apple and Macintosh. Why so far? - Because
Apple is not going to turn up today:
shares on the market grows, sales iMak 's
too, so much so that in some regions of the world's foremost
dealers in the face - all lacking! A recently published
information that the Korean firm Daewoo Telekom and its
a subsidiary of Future Power PC are going to sell in packages
under "IMac", Apple has already filed them in court.
Looks like to make money on someone else's popularity.
In the next issue will be continued
and a description of new models of Power Macintosh
processor G4.
In the 7 th issue, I mentioned about the limit
performance of silicon in the 2 GHz, according
in press have misunderstood me - razyasnyayu: 2GHz - the limit
for freestanding transistors, the information in 1989 for ten
years, as far as I know, the situation has not changed. Started
doped by different substances, to This had not previously used,
the gain - A few percent of performance.
When a few million transistors
collected in 1 cm 2 they start to each other
interfere, and work properly, they can at
much lower frequency. Most importantly, the
increase the clock speed is now constrained
several factors:
1. Conductive path between the
transistors are so close to each
from a friend that there are parasitic coupling
between them.
2. Each transistor has a certain
input capacitance, the charge that it takes time to reduce the
time carriers need to reduce the resistance of conductors
(recently published "copper technology" to replace the
aluminum, but it is "penny").
3. In the process of manufacturing ICs
technology less than 0, 18 micron wavelength
ultraviolet radiation greater than the distance
created between the tracks, out in the
wavelength decreases, and this requires
creation of new photographs, a source
radiation, which does not exist yet.
So the winner will be the one who has to
crystal transistors smaller, better architecture. In this
regard, Power PC exceeds the Pentium. Many have probably seen
advertisement Pentium II, a sort of garbage Pobol audiotapes,
and recently I decided to look in freshly bought PowerMac G3
350 MHz, in hope to see such a "miracle." Pull the
for the ring, door opens, and there is visible only a small
radiator 5h5h1 cm from He looks at one side of the board L2
cache in 1MBayt, the CPU itself is hidden under this board
seated in the connector such as the Socket 7. The shell
thickness of less than 1 CPU, 5 mm, only in the place where the
crystal and the adjacent sink, the thickness is increased to 5
mm.
Immediately after the release for sale
Pentium III 600 MHz Intel to announce that in
soon (at least until the end of the year) to increase the clock
speed is not going to (come:)), and will improve the processor
architecture (finally).
And now about the sound.
In the late 70's when there was a development
with Philips and Sony standard
AUDIO-CD, computers had relatively little RAM and performance of
applying them in digital audio is not
was the question. Nobody thought then about
sampling frequency, and that after 6 years
appear based on this technology synthesizers sound. Therefore,
the standard 44100 has been taken from the ceiling (almost).
True were isolated cases of otsifrovok: firm Roland in 1982
released a rhythm box TR-808, using analog and digital sound
synthesis, sound of drums created an analog generators, all
plates were recorded in the ROM in the digital
code.
The frequency of 44,100 to digitize and clean
subsequent playback, fits, and for use in synthesizers are not
altogether, as it requires to create evenly tempered scale of
large computational resources. In prinipe it
explains why it took so much
years before engineers turned their
eyes on this technology. By the mid-80's
power of computers grew, and there
the first sampling, with pleerami. Taken as a basis for
derivatives and 44,100 - 22050, 11025, etc. Perhaps this
contributed to the software used to create AUDIO-CD, or the
fact that the first samples intended for scoring games, but not
playing music, and sampling rate did not play a big role.
Since then, 44,100 - standard. But this
applicable to machines with tens of hundreds of MHz and the
ILO. But what about the things we on SPECCY? Two years, there
is a General Sound, but during this time he did not become
standard. It is unlikely that this contributed
high price of fees is likely bolnstvu people turned out to not
need an old technology in 1985. In the previous issue
introduced a new 8-bit 4-channel map with direct access to
's capacity - a good alternative to General
Sound, at least not a "black box"
and most can be assembled (according to the scheme
will cost 2 times less GS). But how
seen from the description, there are glitches, and to
again, in 1985. Fantasy-that whether people are missing?
Fixated on a single the same.
Now the frequency output in GS, with a side of drawn
frequency 37, 5 kHz? It is not clear. Could not squeeze out
more? All world tends to parallelize the computation,
here - again go its own way (all
saddled on the Z80). In the MIRACLE # 3 someone
Dmitry suggested that what is sold in GS limit for an 8-bit
audio. For the GS is probably the limit, but not for an 8-bit
audio.
First, a little theory.
How many have already noticed, Speck
rather the optimal machine. When you create a
sound card, you must also use the "highlight", rather than
trying to just copy the old stuff.
Regarding the use of samples for
scoring game, everything is clear - the effect is lost and all.
But when you create a melody better if the samples could loop
to a certain place, and how much to lose. Every sound has 4
phases: attack, decline, support and damping. At each of the
They can organizavat cycle and modulate the amplitude of all
this, the sample will be very short, but it takes a lot of
calculations. They can be reduced through proper organization
of cycles. Cycle should be multiple of 2 ^ x bytes, for
example: 256, 512, 1024 etc. (in the calculation of addresses
Jr. byte is ignored). This in turn will impose some
restrictions on the period, it must be exactly 2 "X bytes.
There still some nuances, but I still miss them.
To get the music needs a table
division factor. Better if they are integral and odnobaynymi.
There are some factors that have very small error, they are
also called "magic" (read more about it in "RADIO" 1990, No. 3,
p. 63). In Once I trying to collect odnogolosy
digital synthesizer of "Moog" on Z80,
decided to calculate the coefficients of frequency division.
Armed with a calculator, plunged into the calculation, in about
2 weeks I found a single-byte series of numbers, which provides
the minimum error. The next day, leafing through the "Radio"
I stumble on the above article -
I calculated the numbers were "the magic" 2 weeks "down the
drain! :) Synthesizer was received with great systems.
In view of samples 2 ^ X and
"Magic" of the coefficients for
system, where the La 1 octave = 440 Hz, the estimated frequency
of O = 21,973 Hz. At the same time the resulting "average"
system will be as same as natural. This frequency is not
unique, there are other with the difference between the nearest
2 ^ (1 / 12).
In the application of 21,973 Hz, all at the top
srezhutsya sound, with a linear transformation it will be
noticeable. But there is a way of nonlinear transformation,
where high frequency is better preserved and less distorted (it
is described in detail "RADIO" 1991 number 11 (page 48) and 12
(P. 47): "... for music signals
maximum power is reduced to 6 dB
one octave, starting at 2 ... 4 kHz.
Therefore, if the device used
LPF 1-th order with a cutoff frequency equal to
2 ... 4 kHz, while the conversion and will come with the rise
of frequencies above 2 ... 4 kHz at 6 dB per octave, it will
not cause an overload at higher frequencies, but will
significantly improve the quality of the conversion. "Producers
various sound equipment because and increase the sampling rate
and bit depth that using a linear transformation, and only this
can save sound quality.
Once I gathered the nonlinear converter is described in
the magazine and used as the ADC-DAC reverb with a bit depth 10
bits. Conducted tests in his home studio, one of those
musicians who heard, no one said bad things about the sound
quality: noise mixer and amp reverb turned out to be more noise,
hear the noise of the reverb, I was able to
only on a professional pulte Mackie
2002, which has a SNR
106 dB.
In my opinion, this converter
is the signal to noise ratio is not less than 70 dB. At a
frequency of 40 kHz in comparison with the original
misstatement was not, a 25 bit reduced the top, but overall
quality was quite high.
All these technical wisdom and
should be used when creating a sound card. Something I did not
tell, but it already in next time.
