The Zilog eZ80 is an 8-bit microprocessor which is essentially an updated version of the company's earlier Z80 8-bit microprocessor.
The eZ80 (like the Z380) is binary compatible with the Z80 and Z180, but almost four times as fast as the original Z80 chip at the same clock frequency. Available at up to 50MHz[1] (2004), the performance is comparable to a Z80 clocked at 200 MHz if fast memory is used (i.e. no wait states for opcode fetches, for data, or for I/O) or even higher in some applications (a 16-bit addition is 11 times as fast as in the original). The eZ80 also supports direct continuous addressing of 16 MB of memory without a memory management unit, by extending most registers (HL, BC, DE, IX, IY, SP, and PC) from 16 to 24 bits.
The processor has a 24-bit ALU (Arithmetic Logic Unit) and overlapped processing of several instructions (a so called pipeline) which are the two primary reasons for its speed. Unlike the older Z280 and Z380 it does not have (or need) a cache memory. Instead, it is intended to work with fast SRAM directly as main memory (as this has become much cheaper). Nor does it have the multiplexed bus of the Z280, making it as easy to work with (interface to) as the original Z80 and Z180, and equally predictable when it comes to exact execution times.
The chip has a memory interface that is similar to original Z80, including the bus request/acknowledge pins, and adds 4 integrated chip selects. Versions are available with on-chip flash memory and on-chip zero wait-state SRAM (up to 256 KB Flash memory and 16 KB SRAM) but there are also external buses on all models. The eZ80 supports a free TCP/IP stack and operating system based on Xinu operating system, as well as a real-time kernel.
Variants
- eZ80Acclaim! is a family of application specific integrated circuits (ASSPs) that feature up to 128KB of Flash memory, up to 8KB of SRAM, and can operate at speeds of up to 20MHz.
- eZ80AcclaimPlus! is a family of connectivity ASSPs that feature up to 256KB of Flash memory, 16KB of SRAM, can operate at speeds of up to 50MHz. It adds integrated 10/100BaseT Ethernet MAC, TCP/IP stack over the eZ80Acclaim! line.
Notes
- ^ Dimitris Gizopoulos, Antonis Paschalis, Yervant Zorian (2004). Embedded processor-based self-test. Springer. p. 16. ISBN 9781402027857.
References
Further reading
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