ICL PERQ 2 T2 Micropolis 1303 spinning down.

David Gesswein djg at pdp8online.com
Sat Jan 2 12:47:56 CST 2021

On Sat, Jan 02, 2021 at 09:29:16AM -0500, Chris Zach wrote:
> Meantime, anyone know how to convert one of Dave G's disk images on the MFM
> formatter to a format that can be read by SIMH? I have been working a lot
> with this thing, and would like to see if any of the data is really there.

The extracted data file will work if the controller isn't too smart so the
OS view of the disk doesn't match the actual disk format. This seems to be
the case for many non DEC systems. DEC liked smart controllers where the disk
has extra data the controller used for storing info it needs
and doing bad block remapping etc. SIMH doesn't deal with the disk level
format so this information needs to be removed and bad block mapping handled.
As far as I know nobody has taken the time to figure out how to do this.

The only way I know currently for certain DEC controllers is to create an
emulator file and use a real machine.

My code will handle bad block remapping for some simple sector/track
remapping that is indicated in the sector header but not for complex stuff
DEC did. It does put the output data in logical sector order.

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