HD6417750RF240DV Renesas Electronics America, HD6417750RF240DV Datasheet - Page 208

• Manufacturer Part Number: HD6417750RF240DV
• Description: MPU 3V 16K I-TEMP,PB-FREE 208-QF
• Manufacturer: Renesas Electronics America
• Series: SuperH® SH7750r

Specifications of HD6417750RF240DV

• Core Processor: SH-4
• Core Size: 32-Bit
• Speed: 240MHz
• Connectivity: EBI/EMI, FIFO, SCI, SmartCard
• Peripherals: DMA, POR, WDT
• Number Of I /o: 28
• Program Memory Type: ROMless
• Ram Size: 48K x 8
• Voltage - Supply (vcc/vdd): 1.4 V ~ 1.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 208-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

Section 4 Caches
3e. Cache miss (with copy-back/write-back)
4.3.4
In order to give priority to data reads to the cache and improve performance, this LSI has a write-
back buffer which holds the relevant cache entry when it becomes necessary to purge a dirty cache
entry into external memory as the result of a cache miss. The write-back buffer contains one cache
line of data and the physical address of the purge destination.
4.3.5
This LSI has a 64-bit buffer for holding write data when writing data in write-through mode or
writing to a non-cacheable area. This allows the CPU to proceed to the next operation as soon as
the write to the write-through buffer is completed, without waiting for completion of the write to
external memory.
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REJ09B0366-0700
The tag and data field of the cache line indexed by effective address bits [13:5] are first saved
in the write-back buffer, and then a data write in accordance with the access size
(quadword/longword/word/byte) is performed for the data indexed by bits [4:0] of the effective
address of the data field of the cache line indexed by effective address bits [13:5]. Then, data is
read into the cache line from the external memory space corresponding to the effective
address. Data reading is performed, using the wraparound method, in order from the longword
data corresponding to the effective address, and one cache line of data is read excluding the
written data. During this time, the CPU can execute the next processing. When reading of one
line of data is completed, the tag corresponding to the effective address is recorded in the
cache, and 1 is written to the V bit and U bit. The data in the write-back buffer is then written
back to external memory.
Physical address bits [28:5]
Write-Back Buffer
Write-Through Buffer
Figure 4.5 Configuration of Write-Through Buffer
Figure 4.4 Configuration of Write-Back Buffer
Physical address bits [28:0]
LW0
LW1
LW2
LW3
LW0
LW4
LW1
LW5
LW6
LW7