• Card Edge Connectors [MCA]

    From Louis Ohland@21:1/5 to All on Wed Oct 13 20:45:55 2021
    https://web.archive.org/web/19980124023206/http://www.molex.com/product/sockets/edgecard.html

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  • From Marco Moock@21:1/5 to All on Thu Oct 14 15:39:13 2021
    Am Wed, 13 Oct 2021 20:45:55 -0500
    schrieb Louis Ohland <ohland@charter.net>:

    https://web.archive.org/web/19980124023206/http://www.molex.com/product/sockets/edgecard.html
    More information (including pictures) is available here: https://en.wikipedia.org/wiki/Micro_Channel_architecture

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  • From Louis Ohland@21:1/5 to All on Thu Oct 14 11:31:46 2021
    Site only good for those that won't take time to learn anything. [IMHO]

    "Despite the fact that MCA was a huge technical improvement over ISA, it
    soon became clear that its introduction and marketing by IBM was poorly handled. IBM had strong patents on Micro Channel architecture system
    features, and required Micro Channel system manufacturers to pay a
    licence fee - and actively pursued patents to block third parties from
    selling unlicensed implementations of it. The PC clone market did not
    want to pay royalties to IBM in order to use this new technology, and
    stayed largely with the 16-bit AT bus, (embraced and renamed as ISA to
    avoid IBM's "AT" trademark) and manual configuration, although the VESA
    Local Bus (VLB) was briefly popular for Intel '486 machines. "

    How much research did IBM put into MCA? Why should they allow cloners to
    strip them of their IP?

    Poor marketing, 'tis true. At the time of introduction [April '87] a
    large chunk of systems ran DOS, single tasking. MCA, OTOH, was build
    with features that made multi-tasking OSs better performing. So delays
    by IBM to introduce OS/2 certainly didn't help demand.

    IBM took significant strides toward ASICs, memory technologies, and
    components. Much reduced demands for support. MCA design with POS darned
    near eliminated jumpers on adapters. Fond memories of DMA / IRQ jumpers
    on ISA cards down towards the edge connectors. Very painful to change
    settings on a card that is in-between other installed cards.

    "For servers the technical limitations of the old ISA were too great,
    and, in late 1988, the "Gang of Nine", led by Compaq, announced a rival high-performance bus - Extended Industry Standard Architecture (EISA).
    This offered similar performance benefits to Micro Channel, but with the
    twin advantage of being able to accept older ISA boards and being free
    from IBM's control. "

    This is stupidware.

    https://ardent-tool.com/tech/System_Bus_or_Bottleneck.html

    Dropping an old ISA card into an EISA slot defeats the advanced features
    of EISA, most notably IRQ sharing. The fantasy that old ISA cards were
    being moved to newer systems en masse is wrong.

    https://ardent-tool.com/tech/MCA_Benefits.html

    I think there is one good page on Github, but it's HTML-ization of a
    Tech Manual.

    Look at https://ardent-tool.com/, MAJ Tom has straightened it up some,
    but it isn't intuitive to us mere mortals.

    Tom has done a bit o' painful hardware probing. BIOS level stuff.

    We are here if you need help findting something.

    More information (including pictures) is available here: https://en.wikipedia.org/wiki/Micro_Channel_architecture


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  • From Louis Ohland@21:1/5 to All on Thu Oct 14 11:44:29 2021
    Oh, before you think I'm pre-emptively nuking other sites, it
    depends. Over the years, there has been plenty of bad tech writing by
    IBM, wrong stuff by IBM, superseded information, whatever.

    After years of calling the yellow / blue glass chips on processor
    complexi as Synchrostream, and the thick aluminum capped chip whatever,
    MAJ Tom did the complex pinout and determined the glass chip is the Bus Interface Controller [BIC], and the thick aluminum capped chip is the Synchrosream Controller [SSC].

    So I looked at the Wiki page, and saw some "so what" stuff, some stuff
    that's re-warmed sludge from the Internet, and stuff that doesn't quite
    fit IBM's business model.

    MCA is a journey, just a shame about the destination... ;)

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