[Simh] VAX Tape Emulation?

[Larry Baker]

Zane,

Your idea of connecting a second disk to your SIMH VAXes will work fine.  Create a second SIMH hard drive for your VAX(es).  Initialize it on the VAX.  Then boot Standalone Backup and make an image Backup Save Set on your second disk.  Or, make an image copy.  Then you'll have a second bootable disk.  Any VAX can boot into Standalone Backup.  You boot SYSE instead of SYS0 with the boot flags.  VMS comes with a command procedure to create the bootable Standalone Backup SYSE directory tree.  Or, just duplicate your SIMH disk image.

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov



> On 25 Jan 2018, at 6:28:14 AM, simh-request at trailing-edge.com wrote:
> 
> Message: 2
> Date: Wed, 24 Jan 2018 17:33:26 -0800
> From: Zane Healy <healyzh at avanthar.com <mailto:healyzh at avanthar.com>>
> To: Paul Koning <paulkoning at comcast.net <mailto:paulkoning at comcast.net>>
> Cc: Mark Pizzolato <Mark at infocomm.com <mailto:Mark at infocomm.com>>, simh <simh at trailing-edge.com <mailto:simh at trailing-edge.com>>
> Subject: Re: [Simh] VAX Tape Emulation?
> Message-ID: <2092BBD6-85AA-45F9-AB8B-83925B64AA4B at avanthar.com <mailto:2092BBD6-85AA-45F9-AB8B-83925B64AA4B at avanthar.com>>
> Content-Type: text/plain; charset=utf-8
> 
> 
>> On Jan 24, 2018, at 2:17 PM, Paul Koning <paulkoning at comcast.net <mailto:paulkoning at comcast.net>> wrote:
>> 
>> 
>> 
>>> On Jan 24, 2018, at 5:07 PM, Mark Pizzolato <Mark at infocomm.com <mailto:Mark at infocomm.com>> wrote:
>>> 
>>> On Wednesday, January 24, 2018 at 2:03 PM, Zane Healy wrote:
>>>> What type/size of tapes does the VAX emulation support?  I was looking
>>>> through the doc’s and it wasn’t obvious to me.  Is there a size limit?
>>> 
>>> How big is your disk?  :-)
>>> 
>>> Really, there is no actual limit on total tape size, since the data format is 
>>> only concerned with tape records which are then processed sequentially.
>> 
>> Then again, SIMH supports limiting the emulated tape size.  The SIMH VAX document shows that it uses this feature: the tape units can be set to a specific size limit, or 0 for unlimited.  The same is true for various other emulations; I see the PDP11 has the same sort of thing, and for example its TMSCP controller defaults to 98 MB (TK50 size).
>> 
>> 	paul
>> 
> 
> How do I set the tape size to 0?  I’d say that’s a stupid question, but I’ve had very little luck finding documentation on the options.  Though I won’t rule out that I might be blind. :-)
> 
> While looking for the answer to that, I may have found a better solution.  It looks like I can create a 50GB disk.  If I can do that, I can move my Alpha disks over to SIMH.  That would actually be my preference.  The two disks I’m the most concerned with are ODS-2.  The other two are ODS-5, and I think there are some filenames from OpenSource software that will have issues with ODS-2, but I can selectively move the data I want backed up to an ODS-2 disk.
> 
> The joke is, my 50GB disk only has about 8GB of data on it, one of the 36GB drives is the big one at about 26GB.
> 
> Zane
> 

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