MSCP - was Re: Unibus / Qbus

Paul Koning paulkoning at
Mon Oct 24 11:46:57 CDT 2016

> On Oct 24, 2016, at 12:34 PM, allison <ajp166 at> wrote:
>> ...
> And the RQDX1/2/3 used T11 for the job so its not that intense save for speed.
> The other part of it is much of the code is likely the interface to the MFM disk and thats
> speed intensive and likely more hardware than software.

FWIW, microcontroller based disk controllers existed well before MSCP.  For example, the CDC 7054 disk controller (for 844 disks, which are basically RP04s, among other things) uses a small 16 bit computer for the top level control, with a magic data mover engine to construct the detailed bit-level track / sector layout.  If you needed a better disk controller, you could modify the firmware (it was downloaded to the disk controller at system boot), though not many people were skilled enough to do so.  But I worked with one, the famous Don Lee at CERL (PLATO development) at the University of Illinois.


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