[Coco] Burke & Burke Hard Disk controller

[Steven Hirsch]

On Fri, 21 Nov 2014, Bill Pierce via Coco wrote:

> I could read from /h0 but not from /h1. After about 15-20 minutes, /h0 
> would quit reading. If I let the system set for a few hours and try 
> again, I would get the same. /h0 would give 15-20 mins service and /h1 
> wouldn't read. I spent the next 2 weeks getting the data off of /h0, a 
> little at the time I kept this going long enough to get all the data off 
> of /h0 and onto vdsks through dw4. Then it all died.

Not that this is a particularly cost-effective solution, but there's a 
very clever device available that's capable of both imaging and emulating 
MFM hard drives:

http://www.pdp8online.com/mfm/mfm.shtml

I built one and have been playing around with it over the past few weeks. 
For conventionally formatted MFM drives (i.e. written with WD-style VLSI 
controller) it works very well.  The real proximate need here is to 
replace the replace the dying IMI drives in my Corvus file servers. 
Unfortunately, these have a proprietary disk controller built up from Z80 
peripherals and a pile-o-TTL chips.  The designer is currently mulling 
over how to best support this.  The emulator should "just work" with a B&B 
controller that's fitted with the recommended WD-1003 controller.

Bottom line:  If money isn't an object (parts for the emulator will run 
between $120-150 depending on how aggressively you shop) this is one way 
to keep a B&B disk subsystem alive.  If you don't care about classic 
purity, the Cloud9 IDE or an SDC is certainly easier on the budget.

I just thought it was an interesting gadget and very cleverly designed.

Steve


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