8' DSDD disk

Jules Richardson julesrichardsonuk at yahoo.co.uk
Mon Jun 6 06:54:14 CDT 2005


On Sun, 2005-06-05 at 17:45 -0700, Eric Smith wrote:
> Patrick wrote:
> > Ok, I don't understand that... Colorburst is (on NTSC), about 3.58 MHz,
> > which isn't easy to derive from 4.77MHz.  I highly doubt IBM's reason
> > for using that speed had anything to do with (at least NTSC) video.
> 
> Yes, that was the reason.  They had a 4x colorburst crystal (14.31818 MHz).
> They divided by three for the CPU clock, and by four for the colorburst.

Does that mean that IBM machines running PAL display rates had a
slightly different CPU clock frequency as the main crystal would be
different? 

[btw, where did we suddenly get an 8-foot floppy from!?]

If the 8088 has an 8 bit bus and the 8086 is 16 bits, is there a good
reason why it didn't get named the 80816? I'm assuming that's what the
last digit in the number signifies...

cheers

Jules



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