Toshiba America Electronic Components (TAEC) has added a chip at the top end of its “TX System RISC” line of general-purpose embedded processors. The 64-bit MIPS-based TX9956CXBG is the first Toshiba CPU based on 90nm process technology, and the first to use Toshiba's TX99/H4 core. It currently supports Linux and VxWorks, and targets multi-function printers and high-end set-top boxes.

TX9956 chip architecture
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Toshiba's TX99/H4 core, at the heart of the new chip, supports the MIPS64 instruction-set architecture and the MIPS-3D application-specific extension from MIPS Technologies. It features a seven-stage dual-issue superscalar pipeline architecture, jointly developed by Toshiba and MIPS, that can execute two instructions simultaneously. The TX99/H4 core contains a dedicated debugging support unit (DSU) and uses an external enhanced JTAG (EJTAG) interface to enable various modes of control such as setting breakpoints, when used with EJTAG in-circuit emulators available from third-party vendors, according to Toshiba. The core also includes an IEEE754-compliant single/double precision FPU (floating point processing unit) and an MMU (memory management unit) supporting 48-double entry JTLB and 8-entry Data TLB. The core can be clocked from 533 to 666MHz.

The TX9956CXBG includes a four-way, set-associative 32KB instruction cache, and a 32KB data cache, along with 256KB of Level 2 cache. The 133MHz 64-bit/32-bit SysAD bus with multiplexed address and data is compatible with Toshiba TX4955/56 chips, for easy upgrades, according to Toshiba. Power supply voltage is 1.25 Volts (internal), with external 3.3V or 2.5V voltages. The chip supports reduced frequency and sleep mode power saving modes.

TAEC VP Shardul Kazi said, “Our customers can upgrade to the TX9956CXBG from existing, lower-frequency processors while keeping the same companion ASICs or off-the-shelf SysAD-compatible chipsets.”

The TX9956CXBG, in a 272-pin, 27 x 27 x 1.27mm lead-free plastic BGA (ball grid array) package is scheduled to sample in July, priced at $45 each in 100-piece quantities. A reference board, designated RBTX9956, will also be available.

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