ARM expands ARM7 line of 32-bit microcontrollers

Electronic News, March 16, 1998

Cambridge, U.K.--Reflecting the rapid rate of growth in the embedded systems market, Advanced RISC Machines (ARM) announced three additions to the ARM7 32-bit microprocessor core family. The new devices will offer features such as 8-kilobyte cache, write buffer, as well as a memory management function.

The additional features on the new ARM740T, ARM720T and ARM710T are designed, ARM said, to enable designers to implement complex systems that require the use of real-time or virtual memory operating systems such as Microsoft's Windows CE, pSOS from ISI and Psion Software's EPOC32.

The cores are implemented on 0.35-micron process and are currently available for licensing. In addition, all three cores have already been licensed by ARM partners, with licensing fees dependent on specific system level design implementations.

The ARM740T, ARM720T and ARM710T enhance the low-cost, low-power advantages of the ARM7TDMI microprocessor core by adding an 8-kilobyte cache, write buffer, and memory management functions. Now, system designers can more easily implement complex systems that require the use of real-time or virtual memory operating systems such as Microsoft's Windows CE, pSOS from ISI and Psion Software's EPOC32.

The ARM740T combines an 8KB cache and write buffer with a memory protection unit, "a combination of features that simplifies the development of embedded applications, such as set-top boxes and modems," according to ARM. Such systems use code developed specifically for an application and do not require the virtual memory management of a full MMU. The ARM740T cache includes a lock-down feature enabling the user to stop areas of cache from being overwritten, making the device suitable for real-time functions such as interrupt handling routines and critical lookup tables.

PDA and Internet applications are the target for ARM710T which has a full MMU enabling the use of operating systems such as pSOS and EPOC32. The virtual memory features provided by the MMU make it possible to safely use code downloaded from a network, such as the Internet, or from an independent developer.

Finally, the ARM720T has the functionality of the ARM710T plus specific support for the Windows CE operating system. The device is designed to be a low cost chip, making it suitable for emerging applications such as using Window CE in PDAs, wallet PC, set-top boxes, smart phones and cars.

All of the new cores utilize ARM's Advanced Microcontroller Bus Architecture (AMBA) standard bus interface for the design of ARM-based ASICs, providing access to ARM's library of standard peripherals. "AMBA also simplifies the testing of deeply embedded ARM cores without additional test logic or test pattern modifications," the company said.