[Simh] Older Source Archives?

[David Holland]

On Sat, 18 Sep 2004 03:33:15 -0700 (PDT), Mark Pizzolato
<mark at infocomm.com> wrote:
> 

<snip>

> The issue that you are observing is that the transfer size specified
> in a QIO operation fails if it is not Odd on SIMH.  Well this is due
> to the fact that you are using a simulated RA device connected to a
> simulated UDA controller.  The OS supplied device driver for this
> device places the even number of bytes transfer size restriction on
> these devices (which is probably a reflection of the underlying
> hardware requirements).  This is documented in the VMS I/O Users
> Guide section entitled "Disk Function Codes".  It says:  "P2--The
> number of bytes that are to be read from the disk, or written from
> memory to the disk. An even number must be specified if the
> controller is an RK611, RL11, RX211, or UDA50"

So it does..   Many thanks! 

> 
> When your test suceeded on "Real Hardware" and the charon-vax, you
> must have been using a disk device that wasn't one of the ones that
> require even by transfer sizes.  SCSI maybe?

Going back and looking at those public access systems, yeah, it looks like they 
were SCSI disks. 

> 
> Clearly you can adjust the affected code to "round up" the desired
> size into a sufficiently large buffer, and then only pass the true
> data size to the requesting application.

My thanks, it looks like someone here already passed your response
onto the SIMH people.  And looking at my inbox, I've already got some
code to test.

Thanks again!

David

> 
> - Mark Pizzolato
>