5C series NTSC ULA 5C114E 8248

edited April 2014 in Hardware
Not sure if this has been mentioned before; I haven't seen anything about it online. Chris Smith's book discusses 6C011E as the NTSC ULA sold in Spectrums in Chile, an Issue 3 style 6C series ULA.

Here we have a much earlier 5C series NTSC ULA, in a Spectrum with a 3.579545 MHz colour crystal which has to be NTSC. 5C114E 8248 would have been made towards the end of 1982 around the same time the 5C112E-2 PAL ULA was being made.

966539_690346807675528_432721294_o.jpg
Post edited by rga24 on

Comments

  • edited April 2014
    Wow :o

    Would be great if the same suite of tests run against the 6C011E ULA in this thread could be run against this?

    I also see an extra resistor just east of the 74LS32 also, that I haven't seen on any other board?

    Ceramic 4532's for good measure too!

    B
    The Spectrum Resuscitation Thread - bringing dead Spectrums back to life
    zx-diagnostics - Fixing ZX Spectrums in the 21st Century (wiki)
    Sinclair FAQ Wiki
  • zubzub
    edited April 2014
    Ooh, looks interesting!

    Documented on the Sinclair FAQ Wiki. :-)

    I guess this includes the 'dead cockroach' fix? I can't see the dead cockroach or any other board modification except the 'spider', mounted atop the Z80.
    FUSE: the Free Unix Spectrum Emulator, also for Windows, OS X and more!
    http://fuse-emulator.sourceforge.net/
  • edited April 2014
    What's odd about that picture is the modulator. UM1233 is a UHF modulator.

    This Spectrum was found in the USA, not by me. It was sent over by Sinclair. This is the quotation from the owner.

    "Those are made in UK, and as far I know, was shipped to the US, to a local company in Cambridge, MA, US, who was part of the MIT campus, and developed software and hardware for the Sinclair here in US, that's all I could find out about, in that time, I bought a big lot of Sinclair stuff, in a MIT flea market almost 2 years ago, and has some receipts, I still have the somewhere here.
    Along those 48k, I got 16 rom cartridges, (5 different titles) already sold the doubles in Ebay a while ago, printers, interface II, the microdrive, a Timex 2068, a 1500, 2 1000, and a lot of other software.
    I think was the people who was developing the Timex, but I'm not sure, I have more pictures in my pictures.
    It's interesting to know a little more about those early times of the sinclair."
  • edited April 2014
    More oddness. The master crystal is only 14 MHz not 14.11 MHz (Chilean NTSC Spectrum) or 14.112 MHz ( TS2068 ). Assuming this ULA uses 224 t-states per line and 264 lines per frame video timing, it will have timing that is quite a way off from the NTSC standard.

    14 MHz
    15.625 kHz line frequency
    59.1856 Hz frame frequency

    14.11 MHz
    15747.767857 kHz line frequency
    59.6506 Hz frame frequency

    14.112 MHz
    15.750 kHz line frequency
    59.65909 Hz frame frequency
  • edited April 2014
    balford wrote: »
    Wow :o

    Would be great if the same suite of tests run against the 6C011E ULA in this thread could be run against this?

    I also see an extra resistor just east of the 74LS32 also, that I haven't seen on any other board?

    Ceramic 4532's for good measure too!

    B

    I have an Issue two 16K Spectrum, 001-250825, that also has a 1K resistor in that position to the left of the Z80. It goes between +5V and the inverted clock signal, 8B on the edge connector.
  • I also have 5C114E Spectrum, same date code, same crystals. It came from Timex's HQ in Middlebury CT.

    8YSc4Yv
  • Not sure why but your picture wasn't showing, I saved it and re-uploaded it.
    I think it is working now.

    IMG-9603.jpg


    How interesting, does it work?
    And there it is, the same resistor.
  • edited October 15
    .
    Renegade wrote: »
    And there it is, the same resistor.
    Are you talking about R73? {See also here as well as the service manual}.
    Like on this U.K. issue 2...
    ing]

    Mark
    Post edited by 1024MAK on
  • edited October 15
    Yes, you're right. :-B

    Never noticed it before. :-/

    But I was actually thinking about another resistor, from my memory, and was lead to point that out incorrectly.

    This was the resistor I was expecting to see:

    cQA07RS.jpg

    I never found out what it does and if it was necessary to be added to the board in order to make it work correctly with the ntsc ula.
    Post edited by Renegade on
  • Renegade wrote: »
    Not sure why but your picture wasn't showing, I saved it and re-uploaded it.
    I think it is working now.
    How interesting, does it work?

    Thanks for fixing my image.
    Yes, it is working. The quality was not that great so I replaced couple of caps and swapped 14MHz xtal with 14.112MHz. Works very well now.

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