Zilog eZ80
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The Zilog eZ80 is an 8-bit
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circ ...
from Zilog, introduced in 2001. eZ80 is an updated version of the company's first product, the
Z80 The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...
microprocessor.


Design

The eZ80 (like the Z380) is
binary compatible Binary-code compatibility (binary compatible or object-code-compatible) is a property of a computer system, meaning that it can run the same executable code, typically machine code for a general-purpose computer CPU, that another computer syste ...
with the
Z80 The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...
and Z180, but almost three times as fast as the original Z80 chip at the same
clock frequency In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the pr ...
. The eZ80 has a three-stage pipeline. Available at up to 50 MHz (2004), the performance is comparable to a Z80 clocked at 150 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 A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical a ...
, by extending most registers (HL, BC, DE, IX, IY, SP, and PC) from 16 to 24 bits. In order to do so, the CPU has a full 24-bit address mode called ADL mode. Z80 register pairs are extended to 24 bits and renamed with U e.g. HL is now HLU etc. But it can still work in the original Z80-compatible mode. The processor has a 24-bit ALU arithmetic logic unit and overlapped processing of several instructions (the three-stage 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 had 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 the original Z80, including the bus request/acknowledge pins, and adds four 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.


Variants

''eZ80Acclaim!'' is a family of eZ80 single chip computers labeled as "application-specific standard products" (ASSP) that feature up to 128 KB of flash memory, up to 8 KB of SRAM, and can operate at speeds of up to 20 MHz. Like other eZ80 variants, it has an external address and data bus and can thus be used as a general purpose microprocessor as well. ''eZ80AcclaimPlus!'' is a family of connectivity ASSPs that feature up to 256 KB of flash memory, 16 KB of SRAM, can operate at speeds of up to 50 MHz. It adds an integrated 10/100BaseT
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
MAC, TCP/IP stack over the eZ80Acclaim! line. Like other eZ80 variants, it has an external address and data bus and can thus be used as a general purpose microprocessor as well.


Use in commercial products

The latest (mid-2015) graphing calculator in the
TI-84 The TI-84 Plus is a graphing calculator made by Texas Instruments which was released in early 2004. There is no original TI-84, only the TI-84 Plus, the TI-84 Plus Silver Edition models, and the TI-84 Plus CE. The TI-84 Plus is an enhanced ve ...
line by
Texas Instruments Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globa ...
, the
TI-84 Plus CE The TI-84 Plus is a graphing calculator made by Texas Instruments which was released in early 2004. There is no original TI-84, only the TI-84 Plus, the TI-84 Plus Silver Edition models, and the TI-84 Plus CE. The TI-84 Plus is an enhanced ve ...
, uses the eZ80 in the 24-bit address mode at a clock rate of 48 MHz. In Europe, the TI-84 Plus CE-T and TI-83 Premium CE are also powered by the eZ80. The EZ80L92 is the primary processor in the
ST Robotics ST Robotics is a twin company based in Cambridge, England, and Princeton, New Jersey, United States. The company designs and manufactures low-cost bench-top industrial robot arms and purpose built Cartesian robots. The company has no sales force ...
robot controller, clocked at 50MHz. It has 128Kb of external RAM and 128Kb of external flash memory.


References

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Further reading

* * {{8bitMCUs Zilog microprocessors 24-bit microprocessors 8-bit microprocessors