RUSH #01 29 мая 1999

Железо

Development Spectrum - The descendants of the processor Z80.

      Copyright 1992, Jack G. Ganssle


    Translation: 1997 (c) Savichev Andrew
V. E-mail: master@satan.spb.su

About the author: Jack Ganssle, general consultant TGG

RUSH>

    Unbelievable! All of us are so accustomed to
good old Z-80 - the heart of our
Spectrum 's and did not even know that the firm
Zilog, its creator, did not stop
this model, a processor and
continues to release much more
committed by its descendants.

    It is difficult to say what it would have
importance for the further development of Speccy,
who knows, maybe in the near future
New models will be equipped with Spectrum'ov
and a new generation of processors ...


              From the translator:


    Some terms are replaced by Russian
equivalents, while others left without
Translation. Omitted some of the "lyrical"
retreat avtora.Ostavleno without translation
Summary and one "dark" to me ;-) place
in the text.


                 Abstract.


    Z80 and its descendants continue to be
extremely modern populyarnymi.Vot
state of a given architecture.


                Preface.


    I just rage, reading advertisements in
press. Magazines want to assure us that
that the only viable processor
for even the most simple applications - it is 50
486 Mhz RISC processor. But how many
designers actually use these form a
CPU in an embedded system?


    At a conference on embedded systems
Andy Rappaport gave convincing
argument is that until we have
relation between performance
processor and its price, in many
applications that are sensitive to the value
factor, smaller CPUs will dominate
on new architectures. Personally, I
prefer 8 and 16 bit CPU.Oni cheap to
These are cheaper tools
funds and are easier to work.
In fact, 8 p. processor has the same
the width that most
ubiquitous peripherals and
can be used more simple
scheme with a smaller number of components by
integration on a chip. 16 and 32 p. bus
often used to speed up transfers
large arrays informatsii.Bolshaya length
commands used to perform more
complex actions in one machine
tsikl.Vyigrysh performance
turns into a loss in value. I
I think that the four most architecture
meet the needs of designers
built sistem.Ne given 4-p.
architectures, which are often
optimal solution for mass
production, I can not recommend
family 8051, 80186, Z80 and 6800 and their
descendants. From time to time I will write
copies of these articles about this semeystv.V
time, my choice fell on the z80.


         Modern Z80 Technology


    Z80 is essentially no different from
the original version introduced more
in the mid 70's. All modern CMOS
versions have the space velocity. Most
a new proposal from Zilog-and contains 20
MHz protsessor.No growth performance
Processor is equally space
the rising cost of ROM and RAM in sisteme.Poetomu
6 and 8 MHz Z80 still
respectable (written in 92g!:
prim.per.) Although the index instructions z80
weak, it is still undoubtedly the best C
computer, compared with the same
8051. Isolated z80 would be dead-end
line, if not highly integrated
64180 processors from Hitachi and z180 Zilog
Which contain the core processor z80.


    64180/Z180 microprocessors include
the functions traditionally related to
peripheral circuits. Designers
chosen architecture is compatible with the Z80,
Z80 gives users the opportunity
use available to them before
Software obespechenie.Staraya Z80
architecture can be transformed without
financial costs for instrumental
system and without any losses
compatibility. The new design is more
attractive at the expense of empowering system
commands, use less energy and
higher levels of integration.


              Description of 64180.


    Peripherals 64180 includes: two
16-bit counter / timers;
programmable controller and regeneration
of wait states, two DMA controller
(PDP), three serial ports with
programmable rate.
Throw in a bit of memory and
Parallel I / O and you'll
have ready computer.

    Like the Z80, the 64180 supports 16
bit I / O addresses. Whenever an IN A, (C) or
OUT (C), A instruction is executed, both
the Z80 and 64180 issue the contents of C
as the low order port address, and the
contents of B as the high 8 bits of the
address. Unlike the Z80, for which few
users ever needed more than an 8 bit
address, 16 bit port addresses are crucial
to the chip's operation.

    All internal peripherals
64180 is the port for the programmer
input / output. Each device has
unique address, upper 8 bits
that - zero. Reserved 64
address at reset, they are in
range from 0000 to 003F.Vozmozhno
initialize the start of a block of registers
internal devices to address:
0000,0040,0080,00 C0. This is especially useful
to avoid conflict with addresses
External I / O ports.


         Programming bus CPU.


   64180 permits the dynamic selection
several bus parameters, including
number of cycles of memory latency and
I / O devices (for coordination with
slow memory and peripherals
I / O) and the rate of regeneration.
Like the Z80, 64180 automatically
produces cycles of regeneration to
save data in a dynamic
pamyati.Kogda heap
absent, the regeneration cycle reduces
CPU performance, so
64180 is possible to disable them.
Register regeneration control lets
to set the refresh rate, adds
cycles waiting for the slow-running
pamyati.Pri resetting set
maximum regeneration (mode
compatibility with the Z80). The slight difference
lies in the fact that 64,180 generates 8p.
address in the cycle of regeneration, while
Z80 7p. Unfortunately, the 1 Mbit dynamic
RAM is required for regeneration of 9p. address
therefore it is necessary to apply
additional external chip.


                 Timers.


    64180 has two independent 16
bit timer that is clocked
CPU's clock. Each can be
programmed to produce
interruption during the transition of content through
zero. Timers automatically
The reload value of the special
registra.Kazhdy timer has 16R. register
data that is read and written in
arbitrary moment and 16R. register
the value of which is reloaded in the
moment of transfer of register contents
Data by 0. Timer Mode
established with the help of a special
control register.


          Serial ports.


    64180 contains three consecutive
device. Two of them - traditional
asynchronous UARTs (ASCI ASCI 0 and 1).
The third - a special port for simultaneous
obmena.Interfeys supports the full
Duplex, 7 or 8 data bits, 1 or 2
stop bits, all types
parity (chetn. / odd.), some signals
modem control and programmable
speed dannyh.Preryvanie
arises in obtaining
symbol, an error or a blank
send buffer. Clocked synchronous
port (CSI / O) - a simple synchronous 8 p.
Half port.On does not support
SDLC and other synchronous connection, but
provides a link to synchronous port
8051 and similar to other processors.


            Interrupt system.


    Like the Z80, 64180 can support
one of three modes of termination of (0, 1 and 2
), Depending on the choice made
programmer using IM
instruktsiy.Krome addition, it supports
new sources of interrupts, as
internal and external (2 new ones, and all
4). New external interrupt sources
available through the inputs INT1 and INT2, are always
processed in mode 2
(Vector), regardless of the selected
other inputs rezhima.Pri Service
Interrupt CPU accesses to the table in
memory to retrieve the address of procedure
Interrupt (vector table
interrupts). Similarly,
Internal interrupts are handled
devices (in mode 2). Z80, all the vectors
Mode 2 formed at the expense of content
Register I (initialized command LD
I, A-st.bayt address) and 8-bit exposed
external device in the loop (interrupt
acknowledge cycle)-ml.bayt adresa.Takoy
same mechanism is preserved in the 64,180 to enter
INT0.Odnako interrupt inputs INT1, INT2
and internal devices are processed
differently. New register contains bits IL
5.6 and 7 of the interrupt vector table for
INT1, INT2 and internal ustroystv.Starshie 8
bits are taken from the register I, as in the Z80.
Inputs INT1, INT2 and internal sources
have a fixed offset from the beginning
interrupt vector table, so the bits
4,3,2,1,0 are not changed by the programmer, and
start address table can be specified in
Registers I and IL.


              The command system.


    64180 exactly does each
command Z80, but faster. Identical to the Z80
all registers, flags, ways adresatsii.Eto
makes for programmers to move from Z80
64180 is very simple. Several new
commands are very useful in some
applications.

    Team SLP sends 64,180 to the regime
extremely low power consumption. Exit from SLEEP
mode is only possible to interrupt or
reset.

    Team 8-bit unsigned
multiplication to produce 16-bit
result holds for 17
clock cycle (17 T-states) and
gives the improvement in overall performance
processor in the calculations (based on this
How you can increase
processor performance as a
integer arithmetic, and on
arithmetic plav.zapyatoy: prim.perev.)
Works with register pairs BC, DE, HL
or SP, and the input operands are contained
per ml. and Art. byte result in the same
register pair.

    Four types of instructions perform TST
non-destructive and between the argument and
battery. TSTIO takes as
argument 8 bit input port / vyvoda.Starshie
8 bits 16R. port automatically
reset to 0.


            Memory management.


    An important advantage of 16P. Processors
had the opportunity to address the large volumes
pamyati.Esli most 8p.
microprocessors, including the Z80, addressed the
64 KB of memory, 16R. addressed both
typically 1-16 MB. More memory
provides accommodation of a larger
amount of data and more complex, and
hence, with large
opportunities and programs. MMU - a mechanism
through which 64,180 may have access
to the memory of 64 Kbytes, but keep in
This compatibility of system commands
Z80. All instructions are executed
still like to 16R. address
space, and the MMU converts 16P.
addresses in 20p. Space
"Logical" address is converted into
address space of "physical". All
space "logical" addresses
divided into 3 parts: 0-3FFFH
converted to any segment of the 16k
1Mb, for example, 0-3FFFH 4000H-7FFFH
converted to any segment of the 16k
1Mb, for example, 10000H-13FFFH 8000H-FFFFH
converted to any segment of the 32k
1Mb, for example, 40000H-407FFH possible
virtually any configuration
virtual (logical) memory. Full
MMU discussion within this article
impossible, we merely point out that
Some compilers support this
mechanism automatically, to develop
software code exceeding 64K.


        Other Z80 compatible CPU.


    64180/Z180 not the only
highly integrated descendants Z80. And Zilog
and Toshiba sell a range of processors
different combination of peripheral
devices and memory on a single chip and
nomenclature of this series expands
ezhednevno.Obe firms sell 84,013 and
84,015, which includes an SIO (Z80
specific serial port
IO), one CTC (again specific
Z80 timer). SIO and CTC in the composition of these chips
completely identical to their ancestors in
Discrete ispolnenii.Krome order in the
84013 and 84015 Watchdog timer (device
to restart in case of failures and hangs
Program: prim.perev.) and the clock
generator. 84015 falls into our hands (to
my great regret) as 100
pediculo QFP, which is due to the presence of PIO,
which requires 20 additional
conclusions. Sold and other
chips, the enumeration of which is interesting rather
"Zhelezyachnikam" than programmistam.Eto
84s50 with 2K internal RAM and 84s01 (Z80, with
integrated circuit clock).


                  Summary


    Does anyone really know what
processors most designers use? I believe
this is a mystery. Chip vendors track
volume sales of CPUs to determine which
ones outsell the others. They're happy to
sell 100 million CPUs to one customer.
This tells us nothing about the number of
designers working with a chip. A thousand
applications being produced in hundred
quantities amounts to few chip sales, but
lots of engineering. What processors do
you use? Why? Let me know and I'll pass
the information on to your fellow readers.
Softaid - Extraordinary Emulators for August
and 16 bit CPUs 8310 Guilford Road,
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