In the early eighties, the Z80B and Z80H at 6 and 8 MHz respectively, were released.

In 1985, the Hitachi HD64180 reached 10 MHz (with some enhancements such that it seems to be reckoned the equivalent of a Z80 at around 13 MHz).

Later, according to https://en.wikipedia.org/wiki/Zilog_Z180 the Z180 reached speeds of 16, 20, ultimately 33 MHz. When were these milestones reached?

Best I've been able to find so far is http://www.z80.info/z80lives.htm dated 1992, which says the ceiling as of the time of writing is 15 MHz. That means the faster variants came later in the nineties?

  • 1
    @Wilson No, that discussed the Z80B and H, the early eighties versions that I briefly mentioned above. It doesn't talk about the later variants that I'm asking about in this question.
    – rwallace
    Commented Feb 13, 2018 at 13:41
  • 2
    I see! I am trying to work out how to retract my closevote then. Commented Feb 13, 2018 at 13:43
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    I'm also not a fan of closing as the similarity with the previous question is that this asks more. Have voted to reopen. @Wilson voting the same would be a lot like retracting a close?
    – Tommy
    Commented Feb 13, 2018 at 14:06
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    A relevant data point to this question, about Z80 compatibles, that is completely irrelevant to the other question, that is only about Z80s, and which I now cannot make part of an answer: the MSX Turbo R's R800 — en.wikipedia.org/wiki/R800_(CPU) — is a 14.32Mhz Z80 compatible that reduces operation costs a lot so that it's comparatively a lot faster than that. It was available in production machines as of 1990. See map.grauw.nl/resources/z80instr.php for relative clock timing, e.g. ADD A, n is two cycles on an R800 rather than seven on a Z80; ADD HL, BC is down from 11 to 1.
    – Tommy
    Commented Feb 13, 2018 at 14:11
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    It would probably be better if Chenmunka also reopened, but I'll throw my hat into the ring.
    – wizzwizz4
    Commented Feb 13, 2018 at 18:35

4 Answers 4


An article from 2000 on embedded.com dates the Hitachi 64180 (which Zilog second sourced as the Z180) to 1985, the Z280 to 1976, but that's almost certainly a typo for 1986, the Z380 to "the mid '90s", the Rabbit 2000 to "last fall" (i.e. 1999), and the eZ80 explicitly to 1999. (Aside: it's an interesting read beyond those data points, giving a lot of technical detail rather than merely a dry recitation of dates).

As per my comment, I'd add to that the R800, which was developed by the ASCII Corporation as an enhancement to the Z80 that had powered MSX machines until then; the bottom dropped out of the MSX market in the interim but it made it to market in the Panasonic Turbo R in 1990.

The 64180's product sheet states that it has an operating frequency up to 10Mhz. The same is true of the Z180. In both cases instructions have already become more efficient than the Z80.

The Z280 includes a clock divider and a clock output, the intention being that you feed it a fast clock and then it produces a divided one for everybody else and inserts wait states if and when necessary so that it isn't talking too quickly. It includes a cache, so a lot of the same considerations apply as with a more conventional clock multiplier, in addition to the instructions generally being more efficiently implemented. It topped out at 12.5Mhz.

The R800 in the Turbo R is clocked at 14.32Mhz — four times the NTSC colour burst, and like the others mentioned here, is more efficient per cycle than a Z80.

The Z380 scales up to 18Mhz, with similar considerations about Mhz not meaning the same thing as on a vanilla Z80.

The Rabbit 2000 "uses an external crystal with a frequency typically in the range from 1.8 MHz to 29.5 MHz". Which I take to mean that it tops out at 29.5 Mhz.

The eZ80 was initially announced as being intended to become available at up to 80Mhz, but it's unclear to me what actually launched. I defer to Raffzahn's existing answer which states that they only actually managed to push it to 50.

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    Well, I never got my hands on any rated above 50 MHz. Updated (2015) Zilog data sheets do only mention 50 MHz.
    – Raffzahn
    Commented Feb 13, 2018 at 20:19
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    @Raffzahn that's easy enough to believe, given the difficulties in predicting what the microprocessor market will want and what you'll be able to produce. But I'm sure the 3 Ghz PowerMac G5 that Steve Jobs promised will be here any day now.
    – Tommy
    Commented Feb 13, 2018 at 20:37
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    Also, keep in mind, a 50 MHz eZ80 with (more or less) classic code is like Fricking fast. It's 20-50 times faster than back in the days, so another 1.6 times faster isn't realy makign a further difference.
    – Raffzahn
    Commented Feb 13, 2018 at 20:40

While it's easy to setup a timeline for early models, it gets harder when the CPU was no longer a dedicated chip, but part of a SoC, or just an ebedded component, as this data is not free available. Even more as later developments, like the eZ80 may be code compatible, but of different internal design. It would be much like comparing an 8086 with a Pentium.

Having said that, spring 2002 was the time the eZ80 became available at 50 MHz. Considering that it got about 4 times the thruput per clock as a genuine Z80, this would set it at a 200 MHz equivalent. As a (more or less) seperate CPU, that'S the top notch Z80 code can run on dedicated/real hardare. Real in a sense that it's hardware made to execute Z80 code direct, not via an (internal) emulation layer or similar.

  • That certainly sounds like the ultimate Z80 compatible as a dedicated chip! But the other ones linked above such as the Z180 seem to have similarly been dedicated chips reaching high (albeit not as impressive) clock speeds in the nineties or late eighties; it seems to me the dates for those should be public knowledge, if one only knew where to look.
    – rwallace
    Commented Feb 13, 2018 at 13:51
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    @rwallace I did two development with the eZ80, and I was quite happy with the result. It's a nice, compact SoC design. After all, the classic, dedicated MPU is gone since quite some time. MPUs have evolved into kind of data center related SoCs, while MCUs have also gained way more complex components (like LAN controllers), so they are as well no longer that simpl port flipeprs they have been. The eZ80 ismore of such a MCU style SoC.
    – Raffzahn
    Commented Feb 14, 2018 at 12:17

I have used Z180 10Mhz version in early 2000 start using Z180 33Mhz in 2006 to 2009 because it was any an easy replacement of the slower Z180's. I think I started to see the fast Z180's in the market around 2005. I don't if you can call that a milestone.


I worked on Hypercom ICE credit card terminals in the noughties but the terminals date from the late nineties. They had dual Z80s running at approx 50mhz (one was used as the crypto engine). The terminals I worked on had 2MB of ram but were still constrained by the 64KB limit of the Z80. A paging scheme was used and the compiler supported the concept of long calls/jumps (24 bit, the upper 8 bits was a page number). The upper 32K was paged.

  • sorry for this necro comment but 50Mhz on Z80 is very unlikely (hypercom employee here). Could you recall the model? Here is a list with images to help you remember. I never worked with the "high-end" ICE6500, though, and I have the most vague recollection that it might have had eZ80, which sort of tallies with 50MHz and 2M RAM. The mainstream ICE 5500 had a Z80 clocked at 14.9MHz with a dedicated crypto chip (Atmel, AVR based) in a SAM slot for RSA.
    – tum_
    Commented May 13, 2019 at 7:01
  • You are probably right. I just assumed the 2nd processor was a z80. I did think it was faster. My experience with it was developing a fixed point BCD library for an FX currency application (dynamic currency conversion for credit card conversions). There was no floating point library support and we needed multiply and divide. I had to fit the whole thing including all the DCC FX support and a compressed BIN lookup table into a single 32k page. As far as I can remember there was a simple dispatch table at the start of each 32k page.
    – Tim Ring
    Commented May 17, 2019 at 9:21
  • ...delighted to be corrected by former Hypercom employee. I visited Hypercom UK offices in Dunfermline, Scotland some time around 2005. We may have even met. Sad to see Hypercom swallowed up by Verifone (who also bought Trintech, a company I worked for in the 90s).
    – Tim Ring
    Commented May 17, 2019 at 9:26
  • POS world is small. A blast from the past for you (can't format properly in a comment): /********************************************************************/ /* FEXDCC.H */ /* */ /* API file for FEXDCC library for Hypercom ICE terminal family. */ /* Copyright (c) Fexo MCMS Ltd, 2003. */ /* Last Updated - 24/9/03 (TR) */ :)
    – tum_
    Commented May 17, 2019 at 11:14
  • Yes, I'm the (TR) in the code snippet above. Small world indeed...
    – Tim Ring
    Commented May 20, 2019 at 9:15

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