UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Gemini 80-Bus System

JohnBHanson · 22nd Oct 2020, 7:31 pm

Check the spec - the version I found on the web stated 321 cylinders.

I would not recommend going higher, with an mfm drive I don't imagine
there will be anything other than the seek motor bashing on the endstop. In
those days they did not have intelegent controllers on board the inteligence
is provided by the xebec which needs to be setup by the configure drive
characteristics command.

I cannot remember the spec - such a long time ago - but I think that
the rodime had ramped seek i.e. the seek accelerated time was not fixed
but accelerated. You could check the set drive characteristics command
but that might also be incorrect.

The fact that the drive transistors were blown - do you know if these
were for the rotation or stepper motor drive?

If you do decide to do it go one track at a time > increments the track
and then d to display the sector and start a few cylinders below 320.

Personally I would not push a hard drive beyond its spec - but you might
have the spec in your documentation.

22nd Oct 2020, 7:31 pm	#469
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 661	Re: Gemini 80-Bus System Check the spec - the version I found on the web stated 321 cylinders. I would not recommend going higher, with an mfm drive I don't imagine there will be anything other than the seek motor bashing on the endstop. In those days they did not have intelegent controllers on board the inteligence is provided by the xebec which needs to be setup by the configure drive characteristics command. I cannot remember the spec - such a long time ago - but I think that the rodime had ramped seek i.e. the seek accelerated time was not fixed but accelerated. You could check the set drive characteristics command but that might also be incorrect. The fact that the drive transistors were blown - do you know if these were for the rotation or stepper motor drive? If you do decide to do it go one track at a time > increments the track and then d to display the sector and start a few cylinders below 320. Personally I would not push a hard drive beyond its spec - but you might have the spec in your documentation.