RL02->11/73 more info

From: Jerome Fine <jhfine_at_idirect.com>
Date: Sat Apr 3 22:20:27 1999

>John Lawson wrote:

> I flesh out an 11/23, attach the RLV11/RL02s, put in one of the
> several OSes that seem to be bootable, and press the big "Go"
> button. Now....
>
> Doesn't the OS on the disk have to be made specific to the
> processing environment it is living in? Like, sysgenned for instance??

Jerome Fine replies:

I can only answer for RT-11 specifically. The DEC developers
prior to 1980 (prior to V4.0) combined the monitor file with
the device driver for a specific hardware device. Starting
with V4.0 of RT-11 in 1980, every monitor file was able to
use any of the many compatible device drivers on the system
device. Naturally that sounds ambiguous. What I specifically
mean is that the monitor file and the resident device driver were
kept as two separate files. Thus any device driver could become
the resident device driver if it is placed on the media for which
it is the native device driver. Combine that with a monitor and
certain other specific files and you have a minimum bootable
RT-11 system. Under these conditions, the media can be booted
via software (in DUP) from any other media. The secret of doing
a hardware boot is that the device driver must be correctly
written to allow a hardware boot and the correct boot programs
must be placed in the boot locations on the media via the command:

COPY/BOOT DEV:monitor.SYS DEV:

where DEV is the name of the hardware device driver and
monitor.SYS is the name of the monitor file.

Since it makes no sense to have the boot programs for a different
hardware device on the media for a different type of hardware,
you can always be sure that if things were correctly set up, the
boot programs on the media will always correspond.

BUT, that is not a required situation. For example, if you
copy an RL02 10 MByte image onto an RD51 10 MByte
image (via COPY/DEVICE DL: DU:), you will also
copy the RL02 boot programs onto the DU: media
(the file structure will also be somewhat incorrect in that
the same media size will now be on the DU:). Originally,
the correct boot program was placed in the correct block
of the media (block zero) via a:

COPY/BOOT DL0:RT11FB.SYS DL0:

and the RL02 hardware boot would correctly boot RT11FB.
Now after you copy the complete DL0: image onto the
RD51, then you can fix the file structure size situation
by the command:

SQUEEZE DU0:

and then put the correct boot program into block zero by:

COPY/BOOT DU0:RT11XM.SYS DU0:

NOTE that none of the files on either media will have
changed. The only difference will be that you can now
(if your boot ROMs allow - for an 11/73 they usually do)
directly hardware boot either the DL0: or the DU0:
The correct monitor file is combined with the correct
device driver via the correct boot program in block zero
placed there via the COPY/BOOT command.

Please ask for some more explanations about RT-11 if
you need more help.

Sincerely yours,

Jerome Fine
RT-11/TSX-PLUS User/Addict
Received on Sat Apr 03 1999 - 22:20:27 BST