Talk:Apple IIe Card

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Anyone know if 800k or 1.44M superdrives can be hooked up through the Y cable? -PZ

  • No, neither are compatible. It will only interface with the platinum Apple 5.25 or UniDisk 3.5 (the latter is the intelligent drive from the IIc, that's snow-white in color). It's also apparently NOT compatible with the Disk II, UniDisk 5.25, DuoDisk 5.25 or Disk IIc.--Apple2gs 19:51, 24 December 2005 (UTC)[reply]

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How did it produce the 1.023mhz speed?[edit]

OK, so there's a 17.234mhz crystal on the board (which AFAIK is mainly there to drive an attached monitor - at 560x384 active pixels within roughly the same space of 512x384 on an original Mac LC... adding up to 704 clocks/scanline for 24.48khz horizontal, and 407 lines/frame for 60.15hz vertical, which you'd better hope your monitor can withstand...), and we can expect there to be a clock signal available from the host machine...

However, 17.234mhz doesn't divide cleanly into 1.023mhz (even for "1.9mhz", we have to assume that it means 17.234/9 = 1.915mhz), the closest we can get is /16 for 1.077mhz or /17 for 1.014mhz; if we clock a divider on both the rising and falling edges to make an effective /16.5 (2/33), that's still 1.044mhz.

And even with the oddball Mac classic and original LC clock of 15.6672mhz (divided down to 7.8336 for the classics), which is 17.234/1.1, it's no better. /15 is 1.045mhz, and /15.5 is 1.011mhz, never mind /16.

To actually produce that clock rate, we need an NTSC colourburst crystal running at 14.31818mhz, which can then be divided by 14 to give 1.022727(r) mhz (or by 7.5, ie 2/15, for 1.90909(r) mhz). But I don't figure any Mac with a PDS slot has such a crystal on board, and even if it did, wouldn't pipe that particular clock through to a connected card.

So, either something funky is happening in terms of resynthesizing that 1.023mhz (and maybe 1.909mhz) clock from another source or by other means... or the statement is false and it merely runs the software at *close* to, but not *at* the original speed, with the slightly different screen refresh rate compensating for that change on one side, and the disc controller simply absorbing it into the usual fairly generous amount of play in terms of rotational speed on the other...?

Can anyone who knows their stuff better confirm which of the two it is, and if it IS running at the original speed, how this is achieved? 146.199.76.255 (talk) 20:54, 15 May 2018 (UTC)[reply]

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