9 Dec
2009
9 Dec
'09
12:48 a.m.
Chuck Guzis wrote:
What's interesting is that the USB model uses an
Altera MAX7000S CPLD
and 32K local SRAM and a FTDI USB-to-parallel chip. The claim is for
63K-1Mbps data rates. Given the buffer size, I'd say that there is
darned little oversampling going on and that the datarate set on the
emulator had better match the one on your system. A 16MHz clock is
used on the MAX7000S.
I'd be surprised if the FTDI chip could actually transfer 32K of track
data before the drive step completes (~3ms if you're emulating a 3.5"
drive). Although you can always defer the first index pulse for a but
while the data finishes uploading...
$DEITY help you if you want to emulate copy-protected discs.
There are also $50-$300 Chinese-origin emulators
available on eBay
and other vendors which use a USB flash drive as storage. Thus far,
I have not been able to get any meaningful technical information from
the sellers.
I wouldn't expect any "meaningful technical information" from them, either.
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/