Not bored with the Boards.

edited September 2015 in Hardware
Going through some old tapes stored rather badly I came across an unlikely item that that I must have stored away quickly with other low grade items : even back then I was loath to throw it away . I had never had an Issue 2 Spectrum which is probably why I kept it as a kind of "reference" item .This Issue 2 board is largely depopulated , with 4 of the lower ram chips missing , the video modulator ripped out , the ULA and ROM missing as well. The heat sink is painted black. But the board itself looks reasonable. And it has got the cockroach that I haveoften heard about . I dare say , what I will probably do is pack it up again ,more carefully this time , for the next 20 years!

Small scale productions of interfaces also meant that non working examples could be obtained cheaply I probably paid a qid or so for 2 (presumed non working) PROGRAMMABLE JOYSTICK INTERFACE from FOX ELECTRONICS . One has a label , and one does not. Really these are quite interesting pieces of tech but I suspect the parts needed to get them working again will be hard to source. I suppose they might even work but there is always a risk in plugging old stuff (or unproven provenance in) . What I mean is that I would probably trust my old interfaces that I bought from new and used until they were not needed . But stuff like this that was just bought very cheaply second hand somewhere is another matter.

Well I suppose the most "cost effective" solution is to set up a "nice display box" of "untrusted items" for looking at only!

Post edited by rich_chandler on
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Comments

  • Yes I suppose many of us have different bits of Speccy junk that is too good to "throw out" but not worth the cost of repairing . I it will be years (if ever) before rebuilds like the one above become an economic proposition . Maybe I should have called this "to good to throw out but...".
  • But what about the new stuff? Where is it all made? The "old stuff" like the Fox was UK made but not many of the new Spec related boards are made in the UK. The Europeans have overtaken the UK as "major" producers of ZX add on boards!!!!(whatever next!) . I was trying to remember where the DivMMC Enjoy was named (oh sorry made) . Div in UK "colloquial" (as per "Div Head" which means dunce ) is a bit derogatory. But I probably don't know where I am "coming from" on that one (I certainly don't know on this site!!)
  • I was trying to remember where the DivMMC Enjoy was named (oh sorry made).
    ---> http://www.bytedelight.com/

    Mark
  • Thanks for that : it is the Netherlands then . I would make a suggestion for the next production run of 50 or so that they change the UK name to the "BrainyBox Interface " interface if that name has not been used before!
  • It's called the DivMMC because it's essentially a version of the DivIDE with the IDE interface replaced with an MMC interface. The DivIDE name was a play on words that makes no sense with the DivMMC, but that's the reason for it.

    I agree it's a bit of a rubbish name :)
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • I don't mean it as an insult to Ben, or his interface. I just don't think it's a particularly clever name. :)
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • So this small run production stuff is quite personal to one bloke then
  • The "DivMMC Enjoy" is an interface made by one person; Ben. It's based on the DivMMC, which was partly based on the DivIDE which was itself implemented by various people in various different versions.
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • I suppose if he ever upgrade it to TZX compatibility (I assume it is not TZX but I don't know where I got that info from) then he could upgrade or rethink the name as well.

    Does any one know why this interface cannot run TZX or if it is poosible . If not why not etc?

    In the meantime to help me remember the name I call it the "Div(s) must Enjoy" interface . After all , Divs are entitled to a "life" and some enjoyment!
  • A TZX file is a tape preservation format. It's rather complex and can include data blocks ranging from the simple data you get in a tap file, to full compressed audio waveforms.
    It's not practical for a spectrum to load and decode these files.
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • Thanks for that . I did not realize that there was such a big difference . Good to know . So this interface will never be upgraded and it has probably reached the final , or near the final stages of its development , probably. Or could extra capacity, processing abilty, be added to the interface to enable it to do TZX? Or is that uneconomic to do?. The Arm chips are cheap now.
  • It's not that it's not doable; that's how the interface1bis is able to use some tzx files, by having a co-processor running at a high clock speed to do the heavy lifting.
    It's more about what the people designing the interfaces are interested in, from a fundamental "what counts as a proper interface" point of view which I admit is entirely subjective.
    I wouldn't see any point in attaching a powerful ARM processor to a speccy for example when you could just do everything on the ARM and not bother with the speccy at all like in the Vega!
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • Ok thanks for that , so stickind with an original ZX Spectrum (which is a lot cheaper 2nd hand than a Vega) as the thing to be interfaced to via the edge connector , what is viable and cost effective ? Has the Div Enjoy reached a kind of cost threshold? Could a cheap Raspberry Pi be interfaced to the edge connector for instance? . Or in your view has this approach gone as far as it can?
  • A Raspberry Pi is a whole computer with a powerful modern processor. It can already emulate multiple Spectrums at the same time so what would be the point of attaching a real one? :)
    My rubbish website including the redrawn Amstrad schematics and the new home of the Sinclair FAQ wiki.
  • To use a Spectrum that can do TZX? .I suppose the question is about whether preserving the original Spectrum for TZX is a viable option or not . I do not know but you seem to know a lot more than me , so your take on this would be interesting to hear. You seem to rate the Vega as good way to go.
  • If you want to use TZX files with a Spectrum, go read this post. [site link]

    Mark
  • Intersting reading . I see it get a bit hot out there! It does not look too easy then!
  • Thanks for the interesting information. It has improved my knowledge a lot
  • guesser wrote: »
    A Raspberry Pi is a whole computer with a powerful modern processor. It can already emulate multiple Spectrums at the same time so what would be the point of attaching a real one? :)

    I have a spare Speccy +3 with a duff disc drive which I'm tempted to mount a Pi with a touch screen in, as a glorified tape player. ;)
  • New naming suggestion for the above interface (and I am only joking of course!!) ; Owen Jones wrote a book called "Chavs" : The Demonization of the Working Class" in 2011 . So why not replace "Div" with Chav? Furthermore "deep analysis" of the "m .m m." in the tittle suggests that he had a stutter and that he was really trying to say "MUST HAVE".So, we have the possible new name for any possible future upraded interface: it could be called "The Chavs "must have" Enjoyable Interface"

    I heard a story about a Belgian language course that included a totally out of date Belgian idiom that had been included in a recent UK language course , The point is that refreshing and weeding out "old idioms" is necessary from time to time. And the noble tradition of giving disadvantaged groups access to the best possible Spectrum interfaces would continue!



  • Re Touch Screen ref above : CPC (Farnell) now has some nice looking touch screens aimed at the Raspberry PI circa £45 . So things seem to be improving quality and price wise for these. Interesting project for a Plus 3
    Thanked by 1RobeeeJay
  • Getting back to the question of the best way of using the many variations on Spectrumness. One way is to consider whether all the various variant routes are all equally valid or whether one route (eg a Vega) is much better : of course this is subjective . I suppose one advantage of sticking with the original Speccy is all that "authenticity" and familiarity , although I find that ,after a long time away from using a Spectrum , the value of this is probably greatly overestimated . But ,if one values the original machines as the "viable heart" of Spectrumness then adding a high powered Interface (to do the "heavy lifting" mentioned above) could be considered as a worthwhile possibility and complementary to owning interfaces like the "Enjoy" (I do like the Enjoy incidentally as it is well made, and the above detailed commentary has improved my understanding of its rationale) . I suppose working it all out is part of the fun of it all and is to be savoured.
  • My "Spectrum perspective" has changed over time . In the 1990s my core system was an Opus Discovery / Spectrum combo so the Spectrum +3 was "non core" and for me its usefulness was very limited The SDC (Spectrum Discovery Club) was still going so everything else was "non core". And these "non core" systems were being sold off for around £20-£30 with "shed loads" of software around the period 1995 to 1997. So I acquired second hand Spectrums , including a +3 and specialist Spectrum keyboards , Also available in this "sell off" period were Atari Sts and other computer stuff along with all kinds of software at "rock bottom" prices

    Who was selling in the 95 -97 period ? Individuals , I suppose were the main source . The software hire clubs were also winding up their operations and selling off their old software . Of course , some places were still selling Educational Software at "top whack" but generally speaking this was a great period to buy up software and hardware very cheaply.For me now my "core systems" are my PCs and everything has to work around these . So my "non core" systems need a "small footprint" to fit in with this core and this means my assessment of the usefulness of my Spectrums also has to change .



  • The Case for a case (for interfaces and small boards)

    Today when a customer buys an external "box" ,like an interface for a Spectrum or maybe an external sound card for a PC or similar , they might expect the PCB to be fully cased but they might nevertheless be sent a bare or uncased product . Why is this and what are the benefits of either approach ie cased or uncased? Is a case always beneficial? My first point would be about the scale of production and about whether "fakery" or "official" large scale production of "knock offs" is a problem for the buyer. Some time ago , I paid a high price for a bona fide official sound card and then more recently I bought the same item again but this time for a much lower price. This second purchase looked similar but it also lacked the usual authentications on the outside of the case ,that were provided by the the manufacturer on the earlier higher priced item I had originally bought online : these missing "identifiers" were the bar code and product number , the date of manufacture , and the ROHS sticker all placed on the back of the case . All these were clearly visible on the higher priced item on the outside of the case . Inside the case the cheaper item had the quality control stickers missing . Was this cheap second item a fake? I think it is hard to say but certainly I had concerns about whether I was buying a proper official version .Neutral feedback was left as I felt that I should be able to express these concerns . But sellers do not like even neutral feedback so it appears that there is very little a buyer can do to express legitimate concerns about possible quality problems . A refund may be offered but sometimes a customers just wants reassurance that I product is "fit for purpose". In any case I opened then up and photographed them out of interest just so I I could play the game of "spot the difference" a little more!!

    So my point here is that with large scale production the case potentially can be used to hide fakery or some unofficial /unauthorised "back door" production. But more beneficially ,at least these cased products (unofficial or not) have the benefit of a case that protects them from static and other accidental damage,

    What about small scale Spectrum Interface production? Years ago most of the interfaces I bought from the likes of Romantic Robot came fully cased . Maybe I acquired some uncased stuff second hand from markets or jumble sales but this was unusual . Cased interfaces were the norm . Recently I have noticed that quite a few Spectrum interfaces available online that are sold as uncased . It is said that this is because it is impossible to case them . Well I understand this as the economics of small scale interface production can be difficult .And plastic moulding is a very different trade from the intricacies of small scale PCB production .So it is not hard to see why this has come about .

    Would I buy an uncased Spectrum interface? I am not sure . But I would certainly be worried about static damage . Of course , cases are easily bought for the likes of the Raspberry Pi where the economies of scale are huge . Maybe a cheap generic case could be made for Spectrum interfaces with optional "push outs" but then the makers would have to agree on a certain standard PCB layout . Otherwise the Spectrum enthusiast is left with the protracted task of making his own case which he may not have the time to do.For now at least I will defer any purchase! (and I still have loads to do in other Spectrum areas)



  • Answer is simple: most new ZX Spectrum Interfaces are made in small numbers by a small number of people who do it because they want to support the retro hobby.

    Production of proper injection moulded plastic cases is possible. But the set-up and tooling costs are very high. In addition the cost per unit for small batches is high even before the set-up and tooling costs are added. So in order to get a reasonable price, you need a run of 10,000.

    Of course, interfaces could be designed to fit inside an off the shelf ABS plastic case. However, then someone has to spend the time and effort drilling and cutting out all the holes.... It is not really practical for more than a handful.

    Now, 3D printing offers better prospects. Ben has done a lot of work on this, hence he can supply his SD card interface in a case. See http://www.bytedelight.com

    Even this takes a lot of work. And it does not work for larger interfaces.

    The most significant cause of static is human beings. However, when components are properly fitted to a circuit board, the risk from a static discharge is reduced compared to handling a chip or MOS transistor on its own. The risk still exists. But as long as you are careful, it is not normally a problem.

    So I recommend the following:-
    Power everything down (including the display / monitor / TV) before attaching or removing an interface.
    Don't wear clothes made of man made fibres. Touch a kitchen cold water tap that is earthed (cross bonded to earth), or the metal work of an electrical item that is known to be properly earthed (only applies to items with three pin plugs that are plugged into mains sockets that have a properly connected earth pin).
    Hold / touch the interface by the edges or on plastic parts (it is okay to hold the edge-connector socket, just avoid touching the contacts, the pins and the solder connections).

    I hope this helps :D

    Mark
  • Would I buy an uncased Spectrum interface?
    That is a question of taste. Some people get excited when they see naked PCBs, while others want them in a burka.
    1024MAK wrote: »
    Don't wear clothes made of man made fibres. Touch a kitchen cold water tap that is earthed (cross bonded to earth), or the metal work of an electrical item that is known to be properly earthed (only applies to items with three pin plugs that are plugged into mains sockets that have a properly connected earth pin).
    Hold / touch the interface by the edges or on plastic parts (it is okay to hold the edge-connector socket, just avoid touching the contacts, the pins and the solder connections).

    Then of course you will need an antistatic mat on your desk, an antistatic floor mat under your chair and antistatic wrist straps on both arms. All these items can be purchased online.
    Alternatively, you can rub your interface on a cat's belly and notice that nothing wrong will happen, that is, besides being bitten.

    'Interface 1bis' for the Sinclair ZX Spectrum
  • edited October 2015
    8-|
    Post edited by balford on
    The Spectrum Resuscitation Thread - bringing dead Spectrums back to life
    zx-diagnostics - Fixing ZX Spectrums in the 21st Century (wiki)
    Sinclair FAQ Wiki
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