howto bitsavers BASIC-11 v2 disk image under simh

Paul Koning paulkoning at
Wed Aug 11 19:59:05 CDT 2021

> On Aug 11, 2021, at 7:06 PM, Fritz Mueller via cctalk <cctalk at> wrote:
>> ...
> Ah ha!  Thanks much, Glen!
> simh is usually pretty good about padding out attached images,

No, I don't think that is true.  What is true is that recent versions of SIMH will create full size container files for disk containers.  But sufficiently old versions did not, so it is not too strange to run into, say, an RK05 image that's shorter than 4800 blocks.

But those normally work; all that happens is that reading too far either gives you zeroes or a read error, I don't remember which.  Since the blocks were never written they should be marked as unused in the file system and nothing will read them, so that's fine.

If there's an unused track at the start of a SIMH image file and in your copy that was missing, that's a different case.  Is that the issue?

Or is the RX02 emulation different from regular disks?


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