[Simh] Corrupt BASIC-PLUS 2.7 tpc issue in SimH > 3.9 (Will Senn)

[Bob Supnik]

With my current head of line source, I get an 'intermediate result'. You 
cannot give the commands in the order specified - attaching prevents 
changes in format. However, if you do the corrected order - enable/set 
format/attach - then the attach succeeds, without the "read only" 
message. Checking internally, the 'object count' routine finds 1900+ 
"objects" (records and metadata markers), and then the "construct map" 
routine works as expected.

I don't know what changes were made in the attach routine in sim_tape.c 
between 3.9x and 4.0, but that's where the problems lies.

/Bob

On 1/2/2016 2:43 PM, simh-request at trailing-edge.com wrote:
> Message: 1
> Date: Sat, 2 Jan 2016 12:43:22 -0600
> From: Will Senn <will.senn at gmail.com>
> To: "simh at trailing-edge.com" <simh at trailing-edge.com>
> Subject: [Simh] Corrupt BASIC-PLUS 2.7 tpc issue in SimH > 3.9
> Message-ID: <56881A4A.1090605 at gmail.com>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
>
> The latest incarnation of SimH does not appear to allow the mounting of
> corrupted tpc images, or at least not the one referred to here. I am
> working with RSX11M-Plus v4.6 using instructions located here:
> http://pdp2011.sytse.net/wordpress/pdp-11/sessions/rsx-11m-plus/
>
> The instructions for adding BP2 to RSX11M-Plus includes mounting and
> using files from a known partially corrupt tpc image loacted at:
> ftp://ftp.trailing-edge.com/pub/rsxdists/basic_plus_2_rsx_v2_7.zip
>
> There are some important files on the tape. But the tape mount does not
> succeed in the latest SimH:
>
> sim> *set ts ena*
> sim> *att ts0 basic_plus_2_rsx_v2_7.tpc*
> sim> *set ts0 format=tpc*
> **
>
> In the latest SimH, when you perform these instructions, the tape image
> is loaded as SimH format and the set ts0 format=tpc line errors out with
> 'Unit already attached'. Reordering logically using:
>
> sim> set ts ena
> sim> set ts0 format=tpc
> sim> att ts0 basic_plus_2_rsx_v2_7.tpc
>
> SimH replies with:
> TS: unit is read only
> Format error
>
> However, in 3.9, the instructions work exactly as described in the first
> set of instruction and the files (that are
> not corrupted) are then accessible in RSX11M-Plus.
>
> As a workaround, I'm using SimH 3.9 to perform the sysgen, etc. and will
> then use SimH latest because of its slew of improvements.
>
> Does this sound like expected behavior or like an issue with the post
> 3.9 SimH? If so, I'll gladly open an issue, but it's weird enough, that
> I thought I would ask first.
>
> Thanks,
>
> Will
>