[Simh] disk file format (rk05)

[Folkert van Heusden]

Hi,

Quick question: what is the file format (on the host system) of a PDP-11
RK05 disk? Just disk-sectors as-they-are? Or do they have headers like the
magtap file format? ( http://simh.trailing-edge.com/docs/simh_magtape.pdf )


regards

--

[Mark Pizzolato]

Appendix 1 (File Representations) of the Simh User’s Guide spells out this detail. The latest version can be found at: https://github.com/simh/simh/raw/master/doc/simh_doc.doc

Folks who don’t directly have access to a Microsoft Word document reader can see the document contents by saving it in a Google Drive.

From: Simh [mailto:simh-***@trailing-edge.com] On Behalf Of Folkert van Heusden
Sent: Tuesday, September 25, 2018 6:39 AM
To: ***@trailing-edge.com
Subject: [Simh] disk file format (rk05)

Hi,

Quick question: what is the file format (on the host system) of a PDP-11 RK05 disk? Just disk-sectors as-they-are? Or do they have headers like the magtap file format? ( http://simh.trailing-edge.com/docs/simh_magtape.pdf )


regards

--

[Paul Koning]

Disks are just sectors. I think that's true generally; if SIMH supported any systems with variable length disk blocks something else would be needed, but the only system I can think of that does so is the IBM 360. (Actually, that one is much stranger, with its keyed sector feature.)

Note that sector sizes may be 512, as for RK05, or something else. RC11 has 64 byte sectors, RF11 is word addressable. And IBM 1620 has 200 digit sectors if I remember right.

paul

Post by Mark Pizzolato
Hi,
Quick question: what is the file format (on the host system) of a PDP-11 RK05 disk? Just disk-sectors as-they-are? Or do they have headers like the magtap file format? ( http://simh.trailing-edge.com/docs/simh_magtape.pdf )
regards
--
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[Bob Supnik]

As Paul said, disks with fixed-length sectors are represented as
fixed-length, data-only records.

The IBM 7094 and Honeywell 516 disks have variable length records, and
the track format includes metadata on record lengths and block
addresses. The IBM 1401 and 1620 disks include metadata for the block
addresses, which is not necessarily based on geometry.

/Bob Supnik

Message: 3
Date: Tue, 25 Sep 2018 09:53:04 -0400
Subject: Re: [Simh] disk file format (rk05)
Content-Type: text/plain; charset=us-ascii
Disks are just sectors. I think that's true generally; if SIMH supported any systems with variable length disk blocks something else would be needed, but the only system I can think of that does so is the IBM 360. (Actually, that one is much stranger, with its keyed sector feature.)