AN2797 Freescale Semiconductor / Motorola, AN2797 Datasheet - Page 11

• Manufacturer Part Number: AN2797
• Description: Migrating from IBM 750GX to MPC7447A
• Manufacturer: Freescale Semiconductor / Motorola

anode and cathode of temperature diode on the MPC7447A. The monitor chip is also connected via the 60x or MPX
bus to a bridge chip/system controller which then communicates with the monitor chip itself using I2C. This second
connection allows thresholding values to be defined so that the monitor chip can generate interrupts via the bridge
chip in a similar manner to the TAU in the IBM 750GX.
3
This section briefly introduces some major features of MPC7447A devices that are not available on the IBM 750GX
and explains how these features can offer significant performance improvements.
3.1
Perhaps the most notable difference between the IBM 750GX and MPC7447A is that of AltiVec. It is a short vector
parallel extension of the PowerPC architecture in terms of both instructions and hardware. It is available on all
MPC7450 family devices and can offer up to 11x performance on significant vs. scalar implementations of some
applications.
The key features of AltiVec are:
The new instructions allow vector/SIMD operations on 128-bit wide vector registers (VR) through any of the four
Altivec execution units: permute, simple, complex, and float, each of which have 2-, 1-, 4- and 4-stage pipes
respectively. These 128-bit VRS can be used as single 128-bit quantity. In addition, VRs can also be used to provide
varying levels of parallelism, yielding a maximum of 16 operations per instruction on 8-bit quantities, or to put into
Freescale Semiconductor
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7447A Specific Features
162 new powerful arithmetic and conditional instructions for intra and inter-element, for example
parallelism support
4 operands per instructions, 3 sources and 1 destination
Pipelined execution units to give
— 1 cycle latency for simple and permute operations
— 3-4 cycle latency for compound/complex operations
No penalty for issuing AltiVec/Integer instruction mix
AltiVec
Figure 6. Temperature Monitoring Device Connection
MPC7447A
Migrating from IBM 750GX to MPC7447A, Rev. 1.0
TEMP_ANODE
TEMP_CATHODE
INT
60x / MPX Bus
ALERT
IRQ
D +
D –
Bridgechip
Monitor
Chip
I
2
C
7447A Specific Features
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