RP04 geometry?

From: John Wilson <wilson_at_dbit.dbit.com>
Date: Thu Mar 30 11:42:27 2000

On Thu, Mar 30, 2000 at 06:18:55AM -0800, Daniel A. Seagraves wrote:
> Since alt.sys.pdp10 is in a big flamewar right now, I guess I'll ask here.
> Does anyone know the correct geomerty of an RP04 pack in 18-bit mode?
>
> I have it as 19 heads, 411 cylinders, and 20 sectors a track, with 260
> word sectors. (18 bit words, 256 data words and 4 header words.)
> I think that's wrong though.

Why? It's the exact same drive and media as used on a PDP-11, just formatted
to 20 sec/track instead of 22. So the cyls and tracks ought to be the same,
just fewer sectors since they're 11% longer. I certainly don't *know* that
it's the same (although I'll bet looking at the source to the ITS "MARK"
routine would be enlightening), but why wouldn't it be? And of course the
headers should be invisible unless you use opcodes 53/63/73.

John Wilson
D Bit
Received on Thu Mar 30 2000 - 11:42:27 BST