Jameco Electronics 2000, 3000 manual Rabbit 8-bit Processor vs. Other Processors

2.1 The Rabbit 8-bit Processor vs. Other Processors

The Rabbit 3000 processor has been designed with the objective of creating practical sys- tems to solve real world problems in an economical fashion. A cursory comparison of the Rabbit 3000 compared to other processors with similar capabilities may miss certain Rab- bit strong points.

•The Rabbit is a processor that can be used to build a system in which EMI is nearly absent, even at clock frequencies in excess of 40 MHz. This is due to the split power supply, the clock doubler, the clock spectrum spreader and the PC board layout advice (or processor core modules) that we provide. Low EMI is a huge timesaver for the designer pressed to meet schedules and pass government EMI tests of the final product.

•Execution speed with the Rabbit is usually a pleasant surprise compared to other pro- cessors. This is due to the well-chosen and compact instruction set partnered with and excellent compiler and library. We have many benchmarks, comparing the Rabbit to 186, 386, 8051, Z180 and ez80 families of processors that prove the point.

•The Rabbit memory bus is an exceptionally efficient and very clean design. No external logic is required to support static memory chips. Battery-backed external memory is supported by built-in functionality. During reduced-power slow-clock operation the memory duty cycle can be correspondingly reduced using built-in hardware, resulting in low power consumption by the memories.

The Rabbit external bus uses 2 clocks for read cycles and 3 clocks for write cycles. This has many advantages compared to a single-clock design, and on closer examination the advantages of the single-clock system turn out to be mostly chimerical. The advantages include: easy design to avoid bus fights, clean write cycles with solid data and address hold times, flexibility to have memory output enable access times greater than ½ of the bus cycle, and the ability to use an asymmetric clock generated by a clock doubler. The supposed advantage that single-clock systems have of double-speed bus operation is not possible with real-world memories unless the memory is backed with fast-cache RAM.

•The Rabbit 3000 operates at 3.6 V or less, but it has 5 V tolerant inputs and has a sec- ond complete bus for I/O operations that is separate from the memory bus. This second auxiliary bus can be enabled by the application as a designer option. These features make it easy to design systems that mix 3 V and 5 V components, and avoid the loading problems and the EMI problems that result if the memory bus is extended to connect with many I/O devices.

•The Rabbit may be remotely programmed, including complete cold-boot, via a serial link, Ethernet, or even via a network or the Internet using built in capabilities and/or the RabbitLink ethernet network accessory device. These capabilities proven and inexpen- sive to implement.

•The Rabbit 3000 on-chip peripheral complement is huge compared to competitive pro- cessors.

10 Rabbit 3000 Microprocessor