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參數(shù)資料
| 型號： | 7026S55J8 |
| 廠商： | INTEGRATED DEVICE TECHNOLOGY INC |
| 元件分類： | SRAM |
| 英文描述： | 16K X 16 DUAL-PORT SRAM, 55 ns, PQCC84 |
| 封裝： | PLASTIC, LCC-84 |
| 文件頁數(shù)： | 9/18頁 |
| 文件大小： | 272K |
| 代理商： | 7026S55J8 |
6.42
IDT7026S/L
High-Speed 16K x 16 Dual-Port Static RAM
Military, Industrial and Commercial Temperature Ranges
17
sectionbywriting,thenreadingazerointoSemaphore1.Ifitsucceeded
in gaining control, it would lock out the left side.
Once the left side was finished with its task, it would write a one to
Semaphore 0 and may then try to gain access to Semaphore 1. If
Semaphore1wasstilloccupiedbytherightside,theleftsidecouldundo
itssemaphorerequestandperformothertasksuntilitwasabletowrite,then
readazerointoSemaphore1.Iftherightprocessorperformsasimilartask
withSemaphore0,thisprotocolwouldallowthetwoprocessorstoswap
8K blocks of Dual-Port RAM with each other.
The blocks do not have to be any particular size and can even be
variable, depending upon the complexity of the software using the
semaphoreflags.AlleightsemaphorescouldbeusedtodividetheDual-
Port RAM or other shared resources into eight parts. Semaphores can
evenbeassigneddifferentmeaningsondifferentsidesratherthanbeing
given a common meaning as was shown in the example above.
Semaphores are a useful form of arbitration in systems like disk
interfaceswheretheCPUmustbelockedoutofasectionofmemoryduring
atransferandtheI/Odevicecannottolerateanywaitstates.Withtheuse
ofsemaphores,oncethetwodeviceshasdeterminedwhichmemoryarea
was“off-limits”totheCPU,boththeCPUandtheI/Odevicescouldaccess
theirassignedportionsofmemorycontinuouslywithoutanywaitstates.
Semaphoresarealsousefulinapplicationswherenomemory“WAIT”
stateisavailableononeorbothsides.Onceasemaphorehandshakehas
been performed, both processors can access their assigned RAM
segmentsatfullspeed.
Another application is in the area of complex data structures. In this
case,blockarbitrationisveryimportant.Forthisapplicationoneprocessor
mayberesponsibleforbuildingandupdatingadatastructure.Theother
processorthenreadsandinterpretsthatdatastructure.Iftheinterpreting
processorreadsanincompletedatastructure,amajorerrorconditionmay
exist.Therefore,somesortofarbitrationmustbeusedbetweenthetwo
differentprocessors.Thebuildingprocessorarbitratesfortheblock,locks
itandthenisabletogoinandupdatethedatastructure.Whentheupdate
is completed, the data structure block is released. This allows the
interpretingprocessortocomebackandreadthecompletedatastructure,
therebyguaranteeingaconsistentdatastructure.
semaphoresalonedonotguaranteethataccesstoaresourceissecure.
Aswithanypowerfulprogrammingtechnique,ifsemaphoresaremisused
or misinterpreted, a software error can easily happen.
Initializationofthesemaphoresisnotautomaticandmustbehandled
viatheinitializationprogramatpower-up.Sinceanysemaphorerequest
flagwhichcontainsazeromustberesettoaone,allsemaphoresonboth
sidesshouldhaveaonewrittenintothematinitializationfrombothsides
to assure that they will be free when needed.
UsingSemaphores—SomeExamples
Perhapsthesimplestapplicationofsemaphoresistheirapplication
as resource markers for the IDT7026’s Dual-Port RAM. Say the 16K x
16 RAM was to be divided into two 8K x 16 blocks which were to be
dedicatedatanyonetimetoservicingeithertheleftorrightport.Semaphore
0couldbeusedtoindicatethesidewhichwouldcontrolthelowersection
of memory, and Semaphore 1 could be defined as the indicator for the
uppersectionofmemory.
To take a resource, in this example the lower 8K of Dual-Port RAM,
the processor on the left port could write and then read a zero in to
Semaphore 0. If this task were successfully completed (a zero was
read back rather than a one), the left processor would assume control
of the lower 8K. Meanwhile the right processor was attempting to gain
control of the resource after the left processor, it would read back a one
inresponsetothezeroithadattemptedtowriteintoSemaphore0.Atthis
point,thesoftwarecouldchoosetotryandgaincontrolofthesecond8K
Figure 4. IDT7026 Semaphore Logic
D
2939 drw 17
0
D
Q
WRITE
D0
D
Q
WRITE
SEMAPHORE
REQUEST FLIP FLOP
SEMAPHORE
REQUEST FLIP FLOP
LPORT
RPORT
SEMAPHORE
READ
SEMAPHORE
READ
,
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 7026S55JI | 功能描述:靜態(tài)隨機存取存儲器 RoHS:否 制造商:Cypress Semiconductor 存儲容量:16 Mbit 組織:1 M x 16 訪問時間:55 ns 電源電壓-最大:3.6 V 電源電壓-最小:2.2 V 最大工作電流:22 uA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSOP-48 封裝:Tray |
| 7026S55JI/2703 | 功能描述:IC SRAM 256KBIT 84PLCC 制造商:idt, integrated device technology inc 系列:* 零件狀態(tài):最後搶購 標(biāo)準(zhǔn)包裝:15 |
| 7026S55JI8 | 功能描述:靜態(tài)隨機存取存儲器 RoHS:否 制造商:Cypress Semiconductor 存儲容量:16 Mbit 組織:1 M x 16 訪問時間:55 ns 電源電壓-最大:3.6 V 電源電壓-最小:2.2 V 最大工作電流:22 uA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSOP-48 封裝:Tray |
| 7026SU | 制造商:Integrated Device Technology Inc 功能描述:70261 16KX16 256K, 5V DUAL-PORT RAM W/INT - Bulk |
| 7026TX | 功能描述:7026TX ETHERNET SWITCH 制造商:red lion controls 系列:N-TRON? 零件狀態(tài):有效 類型:交換機 - 托管型 配置:固定式 + SFP 端口數(shù):26 銅端口:24 銅類型:10/100 光纖端口:- 光纖類型:- SFP/XFP 端口:2 SFP/XFP 型:SFP，千兆比特 PoE 端口:- 連接器類型:RJ45，SFP 電壓 - 輸入:18 ~ 49VDC 侵入防護:- 安裝類型:機架安裝 工作溫度:-40°C ~ 80°C 標(biāo)準(zhǔn)包裝:1 |
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