UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Gemini 80-Bus System

JohnBHanson · 12th Jan 2020, 7:25 pm

The MFB system does not use interrupts or DMA. However it is worth noting that to use software that uses these features the processor card should be in the bottom slot and all the empty slots should be at the top to maintain the DMA and interrupt chain.

Can I assume that you have checked that the reset button does not cause the 813 card to function - that is the red pushbutton on the card. Sometimes slow rise time of the power supply rail can prevent a proper reset - I have seen that with SVC cards that need an in/out to port 0b3h to reset.

12th Jan 2020, 7:25 pm	#306
JohnBHanson Heptode Join Date: Aug 2009 Location: Worthing, Sussex, UK. Posts: 662	Re: Gemini 80-Bus System The MFB system does not use interrupts or DMA. However it is worth noting that to use software that uses these features the processor card should be in the bottom slot and all the empty slots should be at the top to maintain the DMA and interrupt chain. Can I assume that you have checked that the reset button does not cause the 813 card to function - that is the red pushbutton on the card. Sometimes slow rise time of the power supply rail can prevent a proper reset - I have seen that with SVC cards that need an in/out to port 0b3h to reset.