What if,... early PCs (was: stepping machanism

From: Allison J Parent <allisonp_at_world.std.com>
Date: Fri Apr 9 19:16:42 1999

In late 1979 NEC sampled the 765, WD had also been building the 1793.

<Sorry, I should have said that it was not readily achievable for RADIO
<SHACK, not that it wasn't possible. It took RS a few more years before
<they were ready to have MFM in one of their consumer level machines.

No one thought it was needed.

<RS's early FM had some data separation problems; I assume that that was
<due to trying to keep the cost too low?

they tried to cheap out and use the 1771s internal data seperation which
even WD said was stupid! It was far to sensitive to bit jitter and the
SA400 had really bad jitter! I used to have the test fixture and the
disks to exercize them and getting an eyeball pattern on some was damm
hard. It took a few oneshots and a FF package to get good data seperation.
The other problem is the ribbon cable would pickup (and radiate RFI) noise
like mad. If one wasn't careful there would be a ton of common mode noise
on the cable too.

Allison
Received on Fri Apr 09 1999 - 19:16:42 BST