Subject: RE: Dual File Structure CD for RT-11

From: Megan <[email-masked]>
Date: Wed Mar 5 00:33:01 2003

>It does look like ODS-2 and RT-11 FS cannot co-exist, however,
>since they both want to use the 64 blocks at the start of
>the image, unless it's possible that the unnecessary fields in
>each of those two formats can be persuaded to step out
>of each others way. Do you have any details about exactly
>what RT-11 requires in that area? Maybe a disk that boots
>on PDP-11, VAX (VMS), Alpha (VMS) and PC is possible 
>after all :-) 

RT absolutely needs block 1, the Home Block.  If you want the
disk bootable, then 2-5 are absolutely required.  Typically, 
blocks 6 through 6+(2*31)-1 are required for the directory,
but the home block contains a value where the directory is
supposed to start... but I don't believe that RT actually
uses this field, and many utilities certainly don't, assuming
the directory starts in block 6 (not to mention user programs).

					Megan Gentry
					Former RT-11 Developer

+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL   | email: mbg at world.std.com         |
|                                |                                     |
| "this space                    |             (s/ at /@/)             |
|  unavoidably left blank"       | URL:     http://world.std.com/~mbg/ | 
|                                | "pdp-11 programmer - some assembler |
|                  (DEC '77-'98) |  required." - mbg            KB1FCA |
+--------------------------------+-------------------------------------+