Motorola MCP750 Specifications download pdf (Page 51)

Series 6000 Hardware Environmen

4-3

Memory 4

The HN6800 system uses 32-bit addresses for up to four gigabytes of virtual address

space.

Figure 4-1 shows that any processor on the processor board has cached access to local

memory. The local memory resides on a daughter card attached to the processor board.

The daughter card provides up to 128 MB of dynamic or 64 MB of static memory.

The local memory burst rate of 50MHz matches without saturation the bandwidth

demands of both local processors accessing memory concurrently.

The HN6800 memory architecture also supports an Error Detection and Correction

(EDAC) mechanism. This mechanism automatically detects and corrects single-bit errors.

The EDAC mechanism detects multiple-bit errors only upon the ﬁrst read access to a cor-

rupted memory location, but cannot correct them. (The system cannot recover from multi-

ple-bit errors.) The EDAC reacts by raising a precise hardware exception to the processor

initiating the access, which panics the operating system and halts it.

Buses 4

The Series 6000 has two main buses: the processor bus and the local bus.

The processor bus, a dedicated high-performance bus resides on the processor board con-

necting to the main bus, a local bus. The local bus connects the CIO, port, frontplane

(HN6800 only), and HVME interfaces to the processors.

HVME extends the VMEbus standard. The most important extensions are parity error

reporting and fast synchronous burst mode. Fast synchronous burst mode transfers data at

rates up to 40 MB/sec, depending upon system configuration. The HVME bus extension

also provides other hardware-specific improvements not affecting device programming.

Speciﬁc improvements include a larger board size with more power supply pins on the I/O

connectors and eliminating daisy-chained backplane jumpers. Refer to the HVME Exten-

sion Speciﬁcation for details. Note that any VME board works on the HVME bus.

Data Types 4

The Series 6000 supports the following data types:

• Byte (8 bits)

• Half-Word (16 bits)

• Word (32 bits)

• Doubleword (64 bits)

The Series 6000 computer system is a 64-bit machine, but this manual uses the term word

for sixteen bits and longword for 32 bits to remain compatible with other industry standard

systems.

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Motorola MCP750 Specifications Page 51