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While this is not a technical question per se, I finally found something I have no idea and couldn't find any answer online:

How many Cambridge Z88s were made and/or sold?

As it's related, a sub-question would be How long was the Z88 in production?

Delivery started in Jun 1987 and lasted at least until late 1989, but when did production really stop?

After much searching through real paper, I found a September 1987 issue of the UK magazine Popular Computing Weekly mentioning a production capacity of 1000 units per week and an intention to double this 'soon' to 2000. The same issue also features a short article about a deal with SCI, a larger US manufacturing company, to set up production at their Scottish plant. Still no added up production numbers.

Another hint, I just noticed, that one of my Z88s carries a 'Made in Scotland by SCI UK LTD' sticker with a serial number of 007092:

enter image description here

So there were at least 7000 units produced in the SCI plant. Also, since the contract was mentioned in the September 1987 issue in future form, it may be safe to assume that Cambridge LTD manufactured Z88s in their own works for at least 6 months, adding another 6-10k units. So ~20k can be seen as the absolute lowest limit.

AJM
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Raffzahn
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    No idea either. I have proof for one right here in the drawer. – tofro Mar 18 '18 at 09:36
  • @tofro That makes it two :) - Right now I would be already happy about any (educated) guess. – Raffzahn Mar 18 '18 at 11:07
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    If anyone would know, Rakewell would. They've been supporting the Z88 since it came out. I bought Z88 accessories from them back in the day. – scruss Mar 18 '18 at 11:24
  • @tofro Mind to check ifyours got some sticker/serial number? – Raffzahn Mar 19 '18 at 13:35
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    My number (Of a German Keyboard Z88, so pretty late in the game) is significantly higher: 0057903. Rest is identical. But also "Made in Scotland by Sci UK Ltd". This could imply there were at least that many made. – tofro Mar 19 '18 at 22:19
  • @tofro Cool. Thanks. I'd say this puts it at least past 60k units. And no, a German Keyboard isn't any indicator for being late, as it was available form the start. Above unit (7092) is also German. – Raffzahn Mar 19 '18 at 22:23
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    A higher serial number is here: C014593 – scruss Mar 19 '18 at 22:52
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    I wouldn't assume serial numbering started at 000001. It's possible, but sometimes companies start at 010000 because psychologically, people don't always want to get very low-serialed equipment. (Later, in the collector market, of course, those low numbers are gold if the equipment is at all in demand :) ) – Jim MacKenzie Mar 20 '18 at 00:17
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    @JimMacKenzie Sure, but as said, my unit is 007092, and there are even lower ones known like 000698. Even more so, as these are all SCI numbers, which only started to produce the Z88 in late 1987, so even before SCI#000001 ther must be at leaast 6-10,000 units done by Cambridges own shops. – Raffzahn Mar 20 '18 at 01:38
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    @Raffzahn If you know there's a 000698, odds are good indeed that they started at or near 000001 then :) – Jim MacKenzie Mar 20 '18 at 02:15
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    @Raffzahn - Cambridge, like Sinclair before it, didn't have any manufacturing facilities. Many Spectrums were made by Timex in Dundee, and SCI in Irvine would have picked up some of IBM's formerly Spango Valley manufacture by the late 1980s. – scruss Mar 20 '18 at 02:42
  • @scruss As mentioned, this information is taken from that September issue of Popular Computing Weekly, where they explain that the production with a quota of 1000 Units per week started at Cambridges own fabrication, intended to go up to 2000/week soon and that a contract with SCI has been fixed to hand over production to their plant in Scotland larter the year. I don't mind if you can add more here. – Raffzahn Mar 20 '18 at 02:50
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    Relevant: https://www.wired.com/2010/10/how-the-allies-used-math-against-german-tanks/ – snips-n-snails Mar 20 '18 at 03:00
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    @traal Jup, known, except as of now, we only have an extreme small sample of less than 10 while at the same time the upper known number is rather high in comparsion. So we need to shoot a few more Z88 to get their numbers :)) With that formula, the actual sample comes down to ~67500 Units - with a variance allowing an upper end in the millions. So again, lets shoot more. – Raffzahn Mar 20 '18 at 03:39
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    Some serial numbers from eBay: 022979, made in Scotland. 053838 Scotland. 023741 Scotland. 010569 Scotland. 000795 Scotland. 005655 Scotland. 0062271 Scotland. 010759 Scotland. – snips-n-snails Mar 20 '18 at 04:29
  • Also there are some with no serial number badge. – snips-n-snails Mar 20 '18 at 04:31
  • https://web.archive.org/web/20160306232450/http://www.pagetable.com/?p=547 – snips-n-snails Mar 20 '18 at 04:58
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    @Traal I guess the seller simply didn't find them. The serial # is hidden under the folding keyboard foot. – tofro Mar 20 '18 at 08:45
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    @traal did you read the comments? It's always funny how blindly fanboys can bee. Someone sits down and does a real great job in collectin information and puting them in a consistent form and they still go 'nananana but I know its ' :)) (And thanks for the numbers - the tank formula now gives 66718 as total) – Raffzahn Mar 20 '18 at 10:09
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    @tofro Some may also have been removed, as the sticker has been (usually) placed over one of the screws that hold the case together. – Raffzahn Mar 20 '18 at 10:29
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    Thanks for reminding me of my Z88 - It received an internal ROM and RAM upgrade to 512 kBytes each today ;) (Had to rip the serial number, though, as one of the screws hides under it) – tofro Mar 20 '18 at 21:27
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    Had no idea SCI had a plant in Scotland, interesting tidbit, SCI stood for Space Craft, Incorporated - they got their start making components for the Apollo program. – Glen Yates Oct 29 '19 at 20:26

8 Answers8

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I know it's bad style to answer ones own question. Still,I feel the need to publish my findings (*1):

Over the last 3 18 26 months 5 years(*2) I've been able to collect serial numbers of 56 different Z88s, with 62271 (still) being the largest.

Using the so called German Tank Formula, as traal suggested, yields 63382 as a result. So it might be safe to assume that there were considerable less than 100,000 units, possibly even less than 65,000. Unless there's some hidden stash with high serial numbers, that is.

As with many statistical methods there are other approaches and concerns, but Michael Steil has already used it twice to generate rather believable numbers for the C64 as well as for the Xbox, While others made a believable case for iPhones. So I'm inclined to go with it.

Fun part: As so often, the comments of anything about the C64 does carry the outcry of the fanboys. This time it's 'nananana ... statistics are neat but I know better and it's <beloved-fantasy-number>'

*1 - Beside, no-one has provided any answer so far.

*2 - It's getting harder to find more - so Gents, please go thru your storage and pull out your Z88 (I know you got one - everyone has to have one) and post your serial number as comment. There are still many usable lines in my VisiCalc sheet:

enter image description here

Raffzahn
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    Agreed to the fun part, to the extent that I wish I could give you a second +1 for it; my favourite was "it’s not the best research if you don’t know how to get to those numbers". So we've all been wrong about research all this time: the "best research" is starting from a conclusion and finding a way to get to it! – Tommy Jun 20 '18 at 15:17
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    Not sure it's bad style to answer one's own question; that's encouraged practise here on SE. – Omar and Lorraine Jun 21 '18 at 07:47
  • @Wilson I think it is. Beside from the stupidity to ask something one knows to answer, the software is made to disencurage it. So yeah, bad style. And I would have seriously prefered some pointers over my own guessing the number game. – Raffzahn Jun 21 '18 at 08:10
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    Suggest you read https://retrocomputing.stackexchange.com/help/self-answer, this is explicitly encouraged across the entire SE network. If you think differently, you should probably work with meta to get the suggestion changed, but I don't think you'll have much luck since it's a great way to get more knowledge on to the sites. –  Nov 23 '18 at 01:11
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    @paxdiablo Beside that it might be a good idea to abstain from a patronizing tone, even more so it is of no good to spread out a discusion from it's original location. I feel it might not only be a good idea, but quite useful to read prior comments before commenting. Wilson has exactly pointed out the same and I already did make my point clear. Reading helps to avoide superfluous drivel. – Raffzahn Nov 23 '18 at 01:23
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    (1) Was not my intent to be patronising, just to explain why self-answering is acceptable. (2) The discussion is not being "spread", the comment you make about it being bad form is here hence my response is here. (3) Wilson did not provide the link that states self-answering is okay, I would think that would be added valuable informtion, myself. –  Nov 23 '18 at 01:26
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    Self-answering is a good thing if you find an answer yourself finally, especially if no-one else found one, and even if it's not 100%. Most professional questioners will go on with their research after posting their question, and I presume we here are such. I think it's better to have a self-given answer than none. But, Raffzahn, which reasons do you have? – the busybee Oct 26 '19 at 09:47
  • @thebusybee Not really. While you're right from a theoretical POV, reality made me notice, that more often than not, OPs adding their own answer either do so right away, which means it hasn't been a real question at all, but rather a misuse of RC.SE as some blog, or they use it to force their point - including their ability to choose the 'right' answer. Both ways do not benefit RC.SE at all. And while I think above is none of both but useful, I still feel the need to make it clear that I'm not intending either. I also will never select my own answer as 'the right' one. – Raffzahn Nov 05 '19 at 14:08
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    @Raffzahn Or, it is a question that took me a long time to find the answer to, which would have benefited me greatly had it been on SE. So I will create the question I had hours ago, then add the answer I just now found, hoping that some other person with the same question will benefit from my hard-won answer. It looks to you like both the question and answer occurred at the same time, but in my timeline, they did not. – Wayne Conrad Nov 05 '19 at 19:25
  • If the purpose of RC.SE is to be a repository of information, then aren't brain dumps appropriate here? Or do we really need to wait for someone to ask a question before we can answer it? – snips-n-snails Nov 06 '19 at 20:25
  • To my understanding, RC.SE is not a braindump in any way. That's what facebook, twitter and personal blogs are about. It is also not meant to collect an encyclopedia of topics. That's what Wikipedia (and specialized wikis) are for. RC.SE's primary function, as a site, is to help people stuck at an issue by having others go over it and provide hints or in best case solutions.By keeping these solutions permanent available a repository is created. Which serves a great secondary function. That's what differentiates RC.SE from other sites - at the core is always a real issue to be solved. – Raffzahn Nov 06 '19 at 21:15
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    Would not 65536 be the best guess? – Jon Custer Jun 11 '20 at 02:28
  • @JonCuster :)) Well, at the actual number of probes, this would need someine binging a 64112. THen again, I do not belive that some company folding up a business has that much fun. – Raffzahn Jun 11 '20 at 13:37
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    mine's 60806, late model with sealed edge port, made in Irvine (pr. /ur-vihn/, near enough: I'm from near there) by SCI like all the rest – scruss Sep 18 '21 at 01:09
  • @scruss I think we added that already some time ago, didn't we? – Raffzahn Sep 18 '21 at 01:15
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    @Raffzahn - perhaps, yes – scruss Sep 18 '21 at 02:48
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my piece is # 000040 isn't one of the first ? enter image description here

Ivaylo Kunchev
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My Z88 serial number is #034368.

peterh
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StephenM
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Just for evidence - my one has serial #24672: enter image description here

Martin Maly
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My Z88 is a SCI UK Ltd, Made in Scotland model with the serial number #0059854.

Gary Sutherland
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Here are the Serial Numbers for My Z88 (Serial #000169) and that for my Wife's Z88 (Serial #026554). We bought them at different times, hence the large difference. Serial #000169 of my Z88

Serial #026554 of my Wife's Z88

Cane Cave
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Here comes serial from mine z88. Was bought in Croatia and during retro meetings it came to Novi Sad, Serbia. Added two pic because one is not so clear. [Z88 serial num][1]

BobNS
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I am adding second pic. Looks like I can't post more than one. Second pic

BobNS
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