9 Jan
2009
9 Jan
'09
2:24 p.m.
From: toby at coreware.co.uk
To: cctalk at classiccmp.org
Date: Fri, 9 Jan 2009 11:25:54 +0000
Subject: Re: PDP-11/05 returns to life
I've tried out this chasing lights code on the 11/05:
... snip ...
Finally, I have a choice of RX21 + RX02 or RX11 + RX01
on the 11/05. Beyond the added pain of having to toggle in
a longer bootstrap on the RX02, is there any reason not to
go with the RX21/RX02 combo?
Thanks,
Toby
The only thing that pops into my mind is that RX211 uses
"DMA" and RX11 does not. That means that for the RX211, the
NPG chain must be cut (the wire between pins CA1-CB1) of
the slot that will have the RX211. For the RX11 that wire
must be present. If it is not, the system may hang.
That depends on whether the module connects these two pins.
Some SPC modules do this, some do not ...
An other reason to go for RX02 is that with RX02 you can also
read RX01 formatted floppies. The RX02 drive has internally
a switch to act as an RX01. It is ovbious that you can not
read RX02 formatted floppies with the RX01 drive.
And RX02 offers twice the capacity of RX01 ...
If I am wrong in any of this, please correct me :-)
- Henk.