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Old 31st Oct 2019, 12:02 pm   #254
JohnBHanson
Heptode
 
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 661
Default Re: Gemini 80-Bus System

Remember IC1 only has its outputs enabled for the duration of the write cycle. This gives a pulse width that is actually shorter than the SCSI standard. The GM849A fixes this problem but the software has to write the active followed by the inactive state (Which your sample code does).

However your code will only set -SEL active for the duration of the first output cycle. Maybe the resultant pulse is too short for your SCSI to SD converter.
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