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  • ZX Spectrum +2/+3 boards: a small guide

    Originally posted by rkauer View Post
    I know, mate. But the missing logic is just a pair of TTL chips and a ROM.
    My friend, most of +2A Spectrum's actually have the FDD part cut completely away =(

    The Spectrum +2A/B and +3 are part of the +5v/+12v /-12 switching power family (as opposed to the classic 9volt internally regulated family)

    here is a +2A/B motherboard


    I have two +2a's here (one of them is my friend Beaker71's) and they are like the above, also my friend Yorkie4's is the same.


    Here is a +3 motherboard


    As you can see the entire portion where the Zilog FDC and a smidge of supporting logic has been completely cut away.


    Now, some of the later +2A/B Spectrum motherboards were in fact complete +3 motherboards, however they had the Zilog FDC and some supporting logic not installed on the motherboard (probably to save costs) .

    Image missing in action

    The irony is I was reviewing an image of these boards not so long ago - I shall keep looking for an image.

    For the most part the +2A/B motherboards wont have the FDD option available to them, and those that do will require the hard to find Zilog FDC - although I seen replacement FDC's made from a WD1772/3 - apparently Atari ST's are a good source for these chips (*hehehe*)

    However the upside of the +2A/B is that it uses the same ROM as the +3, which means you can easily add an 8bit IDE interface by a small very cheap to make adapter (only a 74LS10, BC327, a 100K resistor, a 40 pin IDE header and a 56 way Edge connector) oh an the +3e ROM =)


    So to complete the ZX (9 Volt) family (and the post) -

    Heres the classic 48K/48K+ Motherboard


    Heres the 128k (Toast Rack) Motherboard



    Here is the 128K +2 (gray model)



    I hope that helps, the +2A/B Spectrum's are very exciting machines to be honest and I am sure that this will make its future owner very very happy.
    Last edited by Zetr0; 2 August 2012, 00:01. Reason: typo's and a bad grandma =)
    Flux Mastah' Zee
    50 L337 1'M W1R3FR4M3

  • #2
    The above post is so full of win that it deserves its own thread on the Oracle area.

    Well done, Zetr0!
    David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
    16 Amigas at home
    3x C= 64
    1 VIC-20
    8 PC (argh) at least one is an AROS/Amithlon unit

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    • #3
      Well I can do a little and complete the pics by providing some pics of a Issue 2 ZX 128K +2A witch as the full +3 pcb but of course with the +3 logic removed from the motherboard.
      This is in my possession and the RF as been removed due to really bad shape of it. The unit is a Spanish version +2A.

      Also have an English Issue 2 with socketed ram chips but pcb is cut as the one in the 1st post. All other +2A that I have is with the pcb cut and all English ones.
      Attached Files
      A1200 ACA1233n || A1000/A2000/A500/A500+/A600|| + 8,16,32 bit systems

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      • #4
        Thanks for posting that JLP, that's a great completion of the boards. For those that need full completion please have take a moment to review www.worldofspectrum.org there's an immense wealth of knowledge and camaraderie' there =)

        BTW, did that Tea2000 chip ever make it too you.... I sent it the same time I think as some 74F74's to a fellow EAB'er in itally... alas he never got his chips =(


        And to the staff member that split this from the sale thread: Cheers
        Flux Mastah' Zee
        50 L337 1'M W1R3FR4M3

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        • #5
          Originally posted by Zetr0 View Post
          As you can see the entire portion where the WDC1773 FDD controller and a smidge of supporting logic has been completely cut away.

          Now, some of the later +2A/B Spectrum motherboards were in fact complete +3 motherboards, however they had the WDC FDD controller and some supporting logic not installed on the motherboard (probably to save costs
          That's interesting. So how does the +2A work with an external disk drive then? Did the 3" disk drives have all the necessary control logic inside the actual drive?
          Thinking about accelerating your A1200? Check out my buyer's guide.

          Projects past and present: Amiga 2000/030 | Amiga 3000/040 | Amiga 4000/060

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          • #6
            Slightly random addition.

            My miniature UHF Video Transmitter (ASTEC UM1233) made from a spare (modified) Sinclair Spectrum 48K RF module: http://www.youtube.com/watch?v=Kjnz7mOPIRw

            Never got round to including the sound; sourced separately in that video.

            Just for fun.
            1.21 gigawatts, Great Scott!!

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            • #7
              @Andy

              Originally posted by AndyLandy View Post
              That's interesting. So how does the +2A work with an external disk drive then? Did the 3" disk drives have all the necessary control logic inside the actual drive?
              Alas my friend a +2A/B cannot use an FDD without replacement of the logic (if available on the motherboard) or by an adapter via the Z80 port.

              Its not that difficult to add a Floppy Disk Drive to any spectrum - from the humble rubber key 48 - upto the +2A/B's, in fact the only difficult part is sourcing some of the components these days.

              When I get caught up with some stuff I plan to make a Floppy Drive controller with a how-to

              Originally posted by skippy View Post
              My miniature UHF Video Transmitter (ASTEC UM1233) made from a spare (modified) Sinclair Spectrum 48K RF module: http://www.youtube.com/watch?v=Kjnz7mOPIRw

              Never got round to including the sound; sourced separately in that video.

              Just for fun.
              LOL, glad I dont have a TV license - that Super Grass Suck LOL!!!

              Awesomes stuff though m8y
              Flux Mastah' Zee
              50 L337 1'M W1R3FR4M3

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              • #8
                Originally posted by Zetr0 View Post
                @Andy

                Originally posted by AndyLandy View Post
                That's interesting. So how does the +2A work with an external disk drive then? Did the 3" disk drives have all the necessary control logic inside the actual drive?
                Alas my friend a +2A/B cannot use an FDD without replacement of the logic (if available on the motherboard) or by an adapter via the Z80 port.
                So it would seem. I had a good ol' peruse of my +2A manual (which for some odd reason, I hung on to, despite getting rid of everything else), the Amstrad-Approved™ method was to buy an Amstrad SI-1 interface and an Amstrad FD-1 diskdrive. It's been a long time!
                Thinking about accelerating your A1200? Check out my buyer's guide.

                Projects past and present: Amiga 2000/030 | Amiga 3000/040 | Amiga 4000/060

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                • #9
                  Wonder why we didn't move this thread to Amioracle and stick it!
                  David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
                  16 Amigas at home
                  3x C= 64
                  1 VIC-20
                  8 PC (argh) at least one is an AROS/Amithlon unit

                  Comment

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