Transcript Chapter 1: Introduction

Tipovi procesora
- Chapter 2 -
Different classes of processors
In order to achieve efficient designs, there exist different classes of
processors:
Microcontrollers
RISC processors
Digital Signal Processors (DSP)
Multimedia processors
Application Specific Instruction Set Processors (ASIP)
Other calasses
Microcontrollers classes of embedded
processors
relatively slow
very area efficient
intended for control - intensive applications
microprogrammed CISC architecture
the number of clock cycles different for various instructions
limited computational and storage resources
relatively small word length data – path (8 or 16 bits)
Microcontrollers classes of embedded
processors – cont.
complex instruction set – provides convenient programming
interface, i.e. dense code
control-oriented application domain
reach set of instruction for bit level data manipulation and
peripheral components like timers or serial I/O ports
simple processor, such as 8051, 6502
nowadays reused in customized form as microcontroller for Ess.
Microcontroller
– block diagram -
Microcontroller – detailed block diagram -
Timer as constituent of microcontroller
RISC classes of embedded processors
evolved from CISC architectures
Harvard architecture –separated data and instruction memory
pipelined instruction execution
offer only very basic set of instructions
instructions are executed at very high speed
all instructions have the same size, and require the same number
of clock cycle for instruction execution
RISC classes of embedded processors - cont.
Load/Store architecture
large number of general purpose registers – reduced number of
memory accesses in a machine program
for a fixed application, the code size for a RISC exceed the code
size of a CISC
popular members of RISC processors for ESs are ARM RISC
core, MIPS RISC core, TRICO
low power consumption (100 mW), suitable for portable systems
with battery supply
Clock Frequency Versus Year for Various
Representative Machines
Fundamental attributes
The key metrics for characterizing a microprocessor include:
 performance
power consumption
 cost (chip area)
high availability (fault tolerant)
Instruction Level Parallelism – Definition
The next step in performance enhancement beyond pipelining
calls for executing several instructions in parallel
Instruction-Level Parallelism (ILP) is a family of processor
and compiler design techniques that speed-up execution by
causing individual machine operations, such as memory loads
and stores, integer additions, and floating-point multiplications,
to execute in parallel.
Parallel processor systems
Parallel processor systems tend to take one of two forms:
• multiprocessors – relatively large tasks, such as procedures or
loop iterations are executed in parallel
• instructions level parallel (ILP) processors – execute
individual instructions in parallel
ILP processors
Processors that exploit ILP have been much more successful
than multiprocessors in the general-purpose workstations/PC
market because they can provide performance improvements
on conventional programs, while this has not been possible on
multiprocessors.
The two more common architectures for ILP are:
• superscalar processors
• Very Long Instruction Word (VLIW processor)
The structure of ILP processors
In the structure of ILP processor some of the execution units
are able to execute integer while the other floating-point
operations
What is ILP ?
ILP processors exploit the fact that many of the instructions in
a sequential program do not depend on the instructions that
immediately precede them in the program
Let consider the following sequence:
What is ILP ? - continue
The dependencies require that instructions 1, 3, and 5 are
executed in order to generate the correct result, but instructions
2 and 4 can be executed before, after, or in parallel with any of
the other instructions without changing the result of the
program fragment.
Division of responsibilities between the
compiler and the hardware
If ILP is to be achieved, between the compiler and the runtime
hardware, the following functions must be performed
•the dependencies between operations must be determined
•the operations, that are independent of any operation has not as
yet completed, must be determined, and
•these independent operations must be scheduled to execute at
same particular time, on some specific functional unit, and must
be assigned a register into which the result may be deposited
Breakdown of tasks between compiler and
runtime hardware
Superscalar processors
– basic principle
Superscalar processors contain hardware that examine a
sequential program to locate instructions that can be executed
in parallel.
This allow them to maintain compatibility between generations
and to achieve speedups on programs that were compiled for
sequential processors, but were compiled window of instructions
that the hardware examines to select instructions that can be
executed in parallel, wich can reduce performance.
Superscalar processors can achieve speedups when running
programs (that were compiled for execution on sequential (nonILP)) processors without requiring recompilation
Superscalar execution
Instead of ‘scalar’ execution where in each cycle only one
instruction can be resident in each pipeline stage, ‘superscalar’
execution is used, where two or more instructions can be at the
same pipe stage in the same cycle.
Superscalar execution allow multiple instructions, that are
adjacent in program order, to be in the stage of processing
simultaneously
Superscalar design require significant replication of resources in
order to support fetching, decoding, execution, and writing-back
of multiple instructions in every cycle.
General superscalar organization
Superpipelining an alternative
approach
An alternative approach to achieving greater performance is
referred to as ‘superpipelining’
Superpipelining exploits the fact many pipeline stages perform
task that require less than half a clock cycle
Superscalar vs Superpipeline
Limitations
The superscalar approach depends on the ability to execute
multiple instructions in parallel
ILP refers to the degree to which, on average, the instructions of
a program can be executed in parallel
A combination of compiler-based optimization and hardware
techniques can be used to maximize ILP.
Fundamental limitations
Fundamental limitations to parallelism with which he system
must cope are :
data dependencies: - true data dependencies
- output dependencies
- antidependencies
procedural dependencies (control dependencies)
resource conflicts (structural dependencies)
Effect of dependencies
Data dependencies
Design issues: ILP versus Machine
Parallelism
ILP and Machine Parallelism (MP) are two related concepts
in processor design so it is very important to make a clear
distinction between them:
ILP exists when instructions in a sequence are independent and
thus can be executed in parallel overlapping.
ILP is a measure how many instructions can be executed
together on an infinitely wide superscalar type machine.
ILP vs Machine Parallelism
MP is a measure of the ability of the processor to take
advantage of ILP
MP is determined by the number of instructions that can be
fetched and executed at the same time (the number of parallel
pipelines) and by the speed and sophistication of the
mechanisms that the processor uses to find independent
instructions.
Both ILP and MP are important factors in enhancing
performance
Example for ILP and MP
The code
for ( i = 0 ; i < 100 ; i ++)
a[i] = a[i] + 1 ;
has considerable amount of parallelism.
If we built a machine with 100 functional units and memory
ports would give us a 100 x speedup.
Example for ILP and MP - continue
In many cases the amount of ILP is simply the ratio of
dependencies (data and structural) and control dependencies to
other types of instructions.
Fewer branches and true data dependencies will increase ILP
More functional units will increase MP
Instruction issue and instruction issue
policy
Machine parallelism is not simply of matter of having multiple
instances of each pipeline stage.
The processor must also be able to identify ILP and to orchestrate
the fetching, decoding and execution of instructions in parallel.
The term instruction issue refer to the process of initiating
instruction execution in the processor’s functional units
The term instruction issue policy refer to the protocol used to
issue instructions
Instruction issue policies
Superscalar instruction issue policies can be grouped into the
following three categories:
•In-order issue with in-order completion
•In-order issue with out-of-order completion
•Out-of-order issue with out-of-order completion
Instruction issue policy - examples
We assume a superscalar pipeline capable of fetching an
decoding two instructions at a time, having three separate
functional units, and having two instances of the write-back
pipeline stage
The examples assumes the following constraints on a sixinstruction code fragment:
– I1 requires two cycles to execute
– I3 and I4 conflict for the same functional unit
– I5 depends on the value produced by I4
– I5 and I6 conflict for a functional unit
In Order Issue and in Order
Completion
In Order Issue Out of Order
Completion
Out of Order Issue and
Out of Order Completion
Another Example of out-of-order execution
Cycle Scalar / In order Super-Scalar / In order
1 Load eax, meml Load eax, mem 1
2
3
4
Super-Scalar / Out-of-Order
Load eax1, meml / Load eax2, mem3
Store mem2, eax Store mem2, eax / Load eax, mem3 Store mem2, eax1 / Store mem4. eax2
Load eax, mem3 Store mem4, eax
Store mem4, eax
Conceptual Description of Superscalar
Processing
Superscalar processor - How execution
progresses
Superscalar Internal Structure
Another Superscalar Internal Structure
Instruction Flow, Register and
Memory Dataflow
VLIW processors - basic principles
VLIW processors architecture requires that programs be
recompiled for the new architecture but achieves very good
performance on program written in sequential languages such
as C or Fortran when these programs are recompiled for a
VLIW processor.
VLIW is one particular style of processor design that tries to
achieve high levels of ILP by executing long instruction words
composed of multiple operations.
VLIW processors, contrary to superscalar approach, take a
differant approach to ILP, relying on the compiler to determine
which instructions may be executed in parallel and provide that
information to the hardware.
VLIW instruction & VLIWprocessor
In VLIW processors, each instruction specifies several independent
operations that are executed in parallel by the hardware
Sheduling sequence of operations for execution on
a VLIW processor with 3 Execution unit – Example
Let consider the following sequence:
VLIW scheduling will be:
VLIW – different flavours of parallelism
The number of operations in VLIW instructions is equal to the
number of execution units in the processor
Each operation specifies the instruction that will be executed in
the cycle that the VLIW instruction is issued.
There is no need for the hardware to examine the instruction
stream to determine which instructions may be executed in
parallel.
The compiler is responsible for ensuring that all of the
operations in an instruction can be executed simultaneonsly.
Pros and cons of VLIW – advantages
The main advantages of VLIW architectures are:
• simpler instruction issue logic, often allow VLIW processors to
fit more execution units onto a given amount of chip space (than
superscalar processors)
• the compiler generally has a larger-scale view of the program
than the instruction logic in a superscalar processor and if
therefore generally better than the issue logic at finding
instructions to execute in parallel
Pros and cons of VLIW – disadvantages
The most significant disadvantages of VLIW processors are:
VLIW programs only work correctly when executed on a
processor with the same number of execution units and the same
instruction latencies as the processor they were compiled.
Code written for a machine with 4 concurrent integer units could
not exploit additional execution units in a later model.
Likewise, code optimized for a newer VLIW with 8 concurrent
integer units would not function correctly on an older machine
with fewer units.
Pros and cons of VLIW –
disadvantages - continue
In addition, if the compiler cannot find enough parallel
operations to fill all of the slots in an instruction, it must place
explicit Nop operation into the coresponding operation slots.
This causes VLIW programs to take more memory than
equivalent programs for superscalar processors.
Defoe Processor – VLIW
Representative
Itanium Bundle
Itanium Register Set
Parallelism of Instruction Execution and
Instruction Issue
The ways to exploit instruction
parallelism: Scalar & Superscalar
The ways to exploit instruction parallelism:
Super-pipeline & VLIW
Typical application of VLIW and
superscalar processors
VLIW processors are often used in digital signal-processing
(DSP) applications, where high performance and low cost are
critical
Superscalar processors are mainly used in general-purpose
computers such as workstations and PCs, because customers
demand software compatibility between generations of a
processor
Improving performance
In general performance can be improved by increasing IPC
and/or by decreasing the instruction count
RISC architecture seeks to increase both frequency and IPC via
pipelining and use of cache memories at the expanse of increased
instruction count
CISC microprocessors employ RISC-like internal representation
to achieve higher frequency while maintaining lower instruction
count
VLIW concept, revived with the EPIC (Explicitly Parallel
Instruction Computing) uses the compiler to schedule instruction
statically. Exploiting parallelism statically can enable simpler
control logic and help EPIC to achieve higher IPC and higher
frequency
DSP classes of embedded processors
designed for arithmetic – intensive signal processing applications
instruction set tuned for fast execution of algorithms like digital
filtering and FFT
special hardware components: hardware multipliers and
dedicated address generation units
instructions can be executed in parallel - VLIW architecture
DSP classes of embedded processors - cont.
unlike RISCs, DSPs use special purpose registers (dedicated
accumulator register)
operate in special arithmetic mode - saturation mode
due to irregularities in the processor architecture, compared to
other processor classes, compilers construction is difficult
the market leader in DSPs is Texas Instruments
Signalno-procesne arhitekture
Danas na tržištu se mogu identifikovati sledeće signalnoprocesne arhitekture:
- ASIC – Application Specific Integrated Circuit
- ASSP - Application Specific Standard Product
- konfigurabilni procesori – Configurable Processor
- DSP – Digital Signal Processor
- FPGA – Field Programmable Gate Array
- MCU - Microcontroller
- RISC/GPP – Reduced Instruction Set Computer / General
Purpose Processor
Kriterijumi koji se koriste za procenu
mogućnosti procesnih elemenata
 Vremenski period od trenutka kada se proizvod zamisli do
trenutka kada se proizvede (Time to market) – veoma važno
 Performanse (Performance) – vrlo važne
 Cena (Price) – vrlo važna
 Sredstva za projektovanje koja su a raspolaganju
(Development Ease) - vrlo važna
 Potrošnja (Power) – srednje važnosti
 Fleksibilnost karakteristika (Feature Flexibility) – nisu od
velike važnosti
Kriterijumi za procenu pogodnosti primene date arhitekture
kod procesiranja signala u realnom vremenu
Tipovi programibilnih VLSI kola
Tipovi programibilnih VLSI kola – nast.
 ASIC - specifično projektovana kola koja izvršavaju jedinstveni zadatak.
Kod ovih kola u kasnijoj fazi projektovanja je veoma teško izvršiti izmene.
Upravljačka jedinica je obično tipa hard-wired.
 ASPP - programibilna arhitektura (odnosi se na stazu podataka) koja je u
stanju da izvršava veći broj različitih zadataka ( aktivnosti ). Upravljačka
jedinica je mikroprogramski zasnovana. Postoji nekoliko programa upisanih u
mikroprogramskoj memoriji pri čemu se svaki program odnosi na jedan
zadatak.
 ASIP - takođe poseduje programibilnu stazu podataka koja se sa aspekta
fleksibilnosti nalazi negde između ASPP-a i DSP-a. U ovom slučaju staza
podataka je nešto uopštenije strukture jer kao i kod standardnih procesora
sadrži RF polje (registarsko polje) i ALU. U odnosu na DSP se razlikuje po
tome što je skup instrukcija dosta ograničen (restriktivan je) a takođe i broj
internih magistrala nije tako veliki. Primena ASIP-a je ograničena na
specifične aplikacije koje se mogu brzo izvršavati.
Tipovi programibilnih VLSI kola – nast.
 DSP - procesori za obradu digitalnih signala, na sličan način kao i
mikrokontrolerske jedinice ( kakve su popularne Intel 80C51 ili Motorola
MC 68HC11 ) su “zaokružene” računarske mašine sa interno ugrađenim
U/I kanalima i memorijom ali sa znatno superiornijim mogućnostima za
matematičkom manipulacijom kao i arhitekturom koja je bolje prilagođena
obradi tipovima podataka (pre svega nizovima) tipičnih za digitalno
procesiranje signala. Danas DSP-ovi su postale ključne VLSI komponente
koje se ugrađuju u komunikacionim, medicinskim, vojnim, industrijskim i
raznim drugim proizvodima široke potrošnje. Istraživači i projktanti ih često
sa opravdanjem smatraju kao klasa mikroprocesora koja je optimizirana za
digitalnu obradu signala.
 MPU su procesorske jedinice opšte namene koje su u stanju, po ceni
redukovane brzine izvršenja, da izvršavaju, bez ograničenja, zadatke bilo
kog tipa.
Množenje sa akumulacijom – specifičnost DSP-a
Veći broj izvršnih jedinica – specifičnost DSP-a
Razlika u memorijskim arhitekturama kod standardnih
MPU-ova I DSP procesora
Generator adresa i
pristup memoriji kod
DSP procesora
Tipična organizacija U/I-a kod DSP procesora
Tipična aplikacija DSP procesora – TMS 320C240
Konvencionalni u odnosu na poboljšani DSP
Organizacija izvršnih jedinica memorije (program & podatke)
kod TMS 320C62xx
SIMD DSP procesori
Princip rada 64 - bitnog sabirača podeljen na četiri 16- bitne sub-reči.
Performansne karakteristike nekih DSP procesora
BDTI - je performansna mera
Paralelno procesiranje nezavisnih instrukcija
TMS320C10
TMS320C206
TMS320VC33
Multimedia processors classes of embedded
processors
relatively new on the market - architecturally related to RISCs
and DSPs
intended for multimedia applications: audio, image, or video
signal processing
the architecture follows the VLIW paradigm
different functional units can operate in parallel
Use general purpose registers like RISCs
Multimedia processors classes of embedded
processors - cont.
The architecture is more regular than in DSPs
the compiler is responsible for exploiting ILP in a program
Examples of multimedia processors are: C6201 (up to 8 parallel
instructions per cycle), Trimedia TM1000 (up to 5 parallel
instructions per cycle)
Multimedia processor – TM1000
Multimedia
processor –
STn8810
ASIPs classes of embedded processors
Microcontrollers, RISCs, DSPs and multimedia processors are
domain - specific: they are tuned for certain application domain,
but not for the given application itself
ASIPs are compromise between domain - specific processors and
non-programmable ASICs
ASIPS are programmable, but they serve only a very narrow
range of application
ASIPs classes of embedded processors - cont1
ASIPs can be parameterized
the basic architecture of an ASIP is fixed, but it can be
customized for a given application by setting a number of different
parameters
word lengths my be adjusted to the required precision, register
files my be sized, and available special hardware components
tuned
Since these parameters are mostly orthogonal to each other,
large number of different configuration of a single ASIP may be
available
ASIPs classes of embedded processors - cont2
ASIPs are very efficient, but a large number of different
compilers are normally required
Retargetable compilers are capable of generating code for any
particular ASIP configuration
source
program P
source
program P
model of
processor Q
compiler for
processor Q
retargetable
compiler
machine code for
executing P on Q
machine code for
executing P on Q
Regular versus retargetable compilation
ASIP in the context of processor HW
implementation class
ASIC
low
ASIP
DSP
flexibility
GPP
high
high
computational performance
low
high
energy efficiency
low
Energy Efficiency
(MOPS/mW or MIPS/mW)
The energy - flexibility gap
1000
100
Dedicated (ASIC)
hardware
ASIPs, FPGAs
Reconfigurable logic
ICORE ASIP: 35MOPS/mW
Programmable DSPs
TMS 320C54:3MIPS/mW
GPP, microcontrollers
SA110: 0.4MIPS/mW
10
1
0.1
Flexibility
Definitions of ASIP related terms
From application point of view
The technical literature uses the acronym ASIP to describe two
different kinds of digital ICs:
ASIP
Application-Specific
Integrated Processor
(any kind of digital IC
used for data processing
and does not imply any
kind of instruction set
oriented or programmable
data processing)
Application-Specific Instruction Set
Processor (Application-Specific
Instruction Processor)
Programmable application-specific
Processor using the concept of an
Instruction set architecture for
Data processing
Evolution of design criteria in
CMOS integrated circuits
Power dissipation in time
“CMOS Circuits dissipate little power by nature. So believed circuit designers”
(Kuroda-Sakurai, 95)
100
Power (W)
x4 / 3years
10
1
0.1
0.01
80
85
90
95
“By the year 2000 power dissipation of high-end ICs will exceed the practical
limits of ceramic packages, even if the supply voltage can be feasibly reduced.”
Gloom and Doom predictions
Power density will increase
VDD, Power and Current Trend
Voltage
Voltage [V]
2
Power
1.5
Current
1
0.5
0
1998
2002
2006
2010
500
Power per chip [W]
200
0
2014
VDD current [A]
2.5
0
Year
International Technology Roadmap for Semiconductors 1999 update sponsored by the Semiconductor
Industry Association in cooperation with European Electronic Component Association (EECA) ,
Electronic Industries Association of Japan (EIAJ), Korea Semiconductor Industry Association (KSIA),
and Taiwan Semiconductor Industry Association (TSIA)
(* Taken from Sakurai’s ISSCC 2001 presentation)
Power Delivery Problem (not just
California)
Your car
starter !
Source: Shekhar Borkar, Intel
Power Consumption New Dimension in
Design
Sources of Power Consumption
• The three major sources of power consumption in
digital CMOS circuits are:
Pavg  pt  CL Vdd2  f clk   I sc Vdd  I leakage Vdd  P1  P2  P3 + P4
where:
P1 – capacitive switching power (dynamic - dominant)
P2 – short circuit power (dynamic)
P3 – leakage current power (static)
P4 – static power dissipation (minor)
Research Efforts in Low-Power Design
Reducing the Power Dissipation
• The power dissipation can be minimized by
reducing:
• supply voltage
• load capacitance
• switching activity
– Reducing the supply voltage brings a quadratic
improvement
– Reducing the load capacitance contributes to the
improvement of both power dissipation and circuit
speed.
Amount of Reducing the Power Dissipation
Gate Delay and Power Dissipation in
Term of Supply Voltage
Power dissipation [ W ]
(normalized)
25
Gate delay [ns]
(normalized)
10
1
1
0.6
3.0
Supply voltage [ V ]
5.0
Needs for Low-Power
•
Efficient methodologies and technologies
for the design of high-throughput and lowpower digital systems are needed.
•
The main interest of many researches is
now oriented towards lowering the energy
dissipation of these systems while still
maintaining the high-throughput in real time
processing.
Baterije – podela
U zavisnosti od načina upotrebe (korišćenja) baterije
delimo na:
• primarne - namenjene da se pune jedanput, koriste
se dok se ne isprazne, a nakon toga se bacaju
• sekundarne – imaju mogućnost da se ponovo pune
i prazne više puta
Osobine
1. Energy density — je mera koja pokazuje koliko energije
baterija može da čuva u zadati volumen ili masu. Ova mera se
može iskazati na sledeća dva načina:
Volumetrijska energy density se obično meri u watthours per liter (Wh/L)
Gravimetrijska energy density se meri u watthours per kilogram (Wh/kg)
2. Memory effect - Neke od sekundarnih baterija poseduju
osobinu poznatu kao memory effect. Naime, ako se ove
baterije koriste dok se u potpunosti isprazne, tada se one
mogu ponovo napuniti do njihovog početno deklarisanog
kapaciteta. No ako su ove baterije delimično isprazne pre
ponovnog punjenja one pokazuju osobine redukcije
energetskog kapaciteta. Nakon većeg broja punjenja i
pražnjenja ove baterije će postati potpuno beskorisne.
Osobine – prod.
3. Cycle life – ukazuje na broj ciklusa punjenja i pražnjenja
koju baterija može da podnese pre nego što postane
neupotrebljiva.
4. Working voltage – dostupan napon od jedne čelije koji je
odredjen hemijskim sastavom baterije.
5. Self discharge – brzina sa kojom se baterija sama po sebi
prazni kada je neiskorišćena.
Tehnologija baterije - tipovi
Ni-Cd – najčešće korišćen oblik. Ove baterije se karakterišu high-energy
current i koriste se za ugradnju u uredjajima koji mogu da pokretaju male
motore. Memorijski efekat, high-self-discharge rate, i low-energy density su
loše osobine ovih baterija, što ih čini neupotrebljivim za cellular phones i
notebook computers.
Alkaline – imaju energy-density nešto bolju od Ni-Cd, i uglavnom se koriste
kao baterije za jednokratnu upotrebu. Postoje i recharchable tip ovih
baterija ali njihova energy-density brzo opada sa višestrukim punjenjem.
Ni-MH – Nickel Metal Hybride baterije se uobičajeno koriste kod cellular
phones i notebook computers jer je njihova cena prihvatljiva, a energydensity je relativno visoka. Na žalost self-discharching rate je visoka što ih
čini neogodnim za odredjene aplikacije. Ovaj tip baterije je dugo bio most
izmedju Ni-Cd i lithium ion-skih, ali je izgubio primat zbog pada cena
lithium-skih baterija.
Tehnologija baterije - tipovi (prod.)
Lithium-ion - karakteriše se velikim energy-density. Standardno se koriste
kod cellular-nih telefona i notebook računara. Veoma su tanke (do 0.5 mm).
Zadnjih godina cena im je drastično pala.
Lithium polymer – karakteriše se high energy density i mogu se formirati
(oblikovati) u različite oblike čime se izvrsno uklapaju sa formom (oblikom)
proizvoda.
Photovoltaic cells - konvertuju ambijentalno svetlo u električnu energiju i
mogu se koristiti za low-power devices kakvi su kalkulatori.
Fuel cells – konvertuju hydro-carbon u električnu energiju i imaju veoma
visoku energy density. Ponovno punjenje ovih ćelija slično je punjenju
upaljača. Imaju od 3 do 5 puta bolju energy density u odnosu na lithium ionske baterije , ali su nepraktične za apikacije koje se odnose na prenosive
elektronske uredjaje.
Kritične metrike za tehnologiju baterije
Implementacija proizvoda
Najbolja tehnologija baterije za prenosive elektronske uredjaje se odredjuje
u fazi procesa analize proizvoda. Projektant mora pri tome da napravi pravi
balans izmedju high energy capacity, male dimenzije baterije (small form
factor), i cene, kako bi napravio uspešan proizvoodni koncept.
Da bi rešenje učinio realnim, proizvodjač mora da sagleda formu (oblik)
baterije, zahteve za ponovnim punjenjem /zamena, mehaničku montažu,
konektore, i power management elektronikom.
Postoji mnogo oblika (formi) baterija. Standardne forme su AA, AAA, C i D
celije, lithium-ske button cell baterije koje se takoreči mogu kupiti u svakoj
prodavnici. Ovi tipovi baterija su poželjni ako želimo da one budu lako
zamenljive od strane širokog kruga korisnika.
Sa druge strane, lithium ion-ske i Ni-MH su dostupne u razne forme
(pravougaone, ne cilindrične, i dr.) kao i neke forme koje se prave po
narudžbini.