[HN Gopher] Using Mass Storage Devices on Simh PDP-11/RT-11: Pap...
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       Using Mass Storage Devices on Simh PDP-11/RT-11: Paper Tape,
       Diskette, Dectape
        
       Author : zdw
       Score  : 21 points
       Date   : 2022-12-28 15:52 UTC (3 days ago)
        
 (HTM) web link (bigdanzblog.wordpress.com)
 (TXT) w3m dump (bigdanzblog.wordpress.com)
        
       | zh3 wrote:
       | I wrote various device drivers for RT-11 back in the day,
       | including for one of the first winchesters (Rodime 5Mb, which was
       | a big step-up from 8" floppies - so much so I partitioned the
       | driver into 8 separate areas). The boot ROM was 256 words, and in
       | there was boot code for the winchester, 8" and 5 1/4" floppies
       | and a CLI to select between them (including the unit number).
       | 
       | One of the tricks I recall used the need to load locations 100
       | and 102 with the vector and processor status word for the BEV
       | (bus event/timer) interupt. At the end, I needed 3 words to load
       | the read sector command for the 8" floppy but only had 2 left.
       | Noticing that the read sector command was 204, I got that by
       | shifting the leftover address for the BEV vector processor status
       | word up one bit (102 => 204) and finished the job with a word to
       | spare.
        
       | OneHeartCancer wrote:
       | [dead]
        
       | AnimalMuppet wrote:
       | "Mass storage".
       | 
       | "Diskette".
       | 
       | Wow, the world has _changed_.
        
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       (page generated 2022-12-31 23:01 UTC)