2.11BSD on two RL02 drives? Probably not, but...

emanuel stiebler emu at e-bbes.com
Fri Aug 4 13:46:47 CDT 2017


On 2017-08-04 14:18, Noel Chiappa via cctalk wrote:

> Exactly our plan (although the USB is left until after we get the SD running).
>
>     > USB with 480MHz is fast enough
>
> I think our plan was to skip that speed, and go with the next one down,
Probably sufficient for a start ...
 > on
> the grounds that the analog part at that speed would be too tricky for us.

No, it isn't.

>     > the old 3v3 level, spi-derivative is very simple to implement. The
>     > 4-bit mode takes a little longer
>
> I think we're using the SPI at the moment, not the 4-bit (we discussed both,
> but I _think_ we went with the one-bit to start with), but I could be wrong -
> Dave will hopefully pipe up if I blew that one.

You use container files in fat16, or simply 1:1 block mapping?

> IIRC our reasoning was that the SPI was the very simplest one to do, for an
> initial implementation; if we later need the speed, and go to the 4-bit, all
> the init/etc will already be working.

Sure.

>     > Did you wire-wrap this thing?
>
> Yes (for one card out of two - below), but that wasn't the problem.
>
> The problem is that we're using two cards (one to plug into the QBUS, and one
> with the FPGA on it - surprise, surprise, nobody makes an FPGA protyping card
> that plugs into a QBUS :-), and the two are connected with a cable; it was
> the cable that was causing the noise (cross-talk - we neglected to put a
> ground line between each pair of signal lines).

I agree some how with your approach, but it leads to debugging of 
issues, you wouldn't have on real boards ...



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