Date   : Sun, 28 Dec 1997 21:54:22 GMT
From   : Theo Markettos <theomarkettos@...>
Subject: Re: disk controller info

On Sun, 28 Dec 1997 14:08:56 +0000, viewtronix@... said:

> hii
>
> Does anyone have info on the 8271 and 1770 disk controllers?  I'm looking
> for things such as pin outs, and other general data on the controllers.

For the pinouts of the 8271 and 1770, look on Acorn's FTP site, where they
have circuit diagrams of the Model B and Master 128, which has 8271 and 1770s
in them respectively.  The site is@..., although I think it is
recommended you access it via http at http://www.acorn.com

On The BBC Lives site there is a manual of HDFS in PostScript form which,
on pages 40 and 41, gives details of the 8271 command set.  I've got a text
file giving command details of the 1770 that I picked up from a website
somewhere, which I could send a copy to anyone who wanted it.

> Also, on a similar line, would it be possible to use the 37C65 disk
> controller in the BBC, with modifications, so that high density writing is
> possible, up to 1.44mb on 3 1/2 inch drives?  I know this would require a
> re-write of the filing system, but could it be done?

I don't see why one couldn't be hooked up to the 1 MHz bus.  I haven't got
experience of this particular device, but the only potential problems I can
forsee are a) getting it to run its bus speed slow enough for the 1 MHz bus,
and b) managing with programmed IO because DMA is not available.

HD discs could be a problem because you might have difficultly getting the
data rate required out of a Beeb.

-- 
Theo Markettos
theo@...