Paul. The RM06 has its own massbus id. The device can also emulate existing dec
disks, which means no changes needed. But when identified as an RM06 it becomes
a bit more interesting as this device does not have a fixed size. Similar to
mscp in that way. It has fixed numbers for sectors/track and tracks/cylinder
but the number of cylinders depends on the actual disk. So the os must figure
disk size out at runtime.
I know rsx does it, as I have the sources. I would expect that Mentec also
added this for RSTS/E but I have not actually checked that.
Johnny
Paul Koning <paulkon...@comcast.net> skrev: (11 december 2017 15:38:26 CET)
>
>
>> On Dec 10, 2017, at 5:12 AM, Johnny Billquist <b...@softjar.se> wrote:
>>
>> Rich. This is a nice thing. Thanks.
>>
>> I have one question/wish, though.
>> I don't know if you were aware of a device called the RM06. This was
>a Massbus disk created by Shelby, which was varible size.
>> It would be a really nice thing to emulate. I can probably reverse
>engineer it from the RSX driver, and I don't know which systems ever
>supported it. RSX for sure. Possibly also RSTS/E, but beyond that is
>more uncertain. Most people and systems had moved on from Massbus
>before this drive came out.
>
>RSTS should be able to handle a third party Massbus disk if it
>identifies itself by the ID code of a DEC disk and has the same
>geometry. (More precisely: if it has more cylinders than the original,
>that would be ok, those would be ignored. But track and sector counts
>must be exact.)
>
>With the source kit, you could add a new disk model, it isn't all that
>hard though it is completely undocumented. I suppose it might be
>possible to *replace* an existing entry. Haven't looked at that.
>Studying the sources should tell us.
>
> paul
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