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boards:sbc:65c816_ecb_sbc:65c816_ecb_sbc [2017/12/25 15:28]
borutk minor changes
boards:sbc:65c816_ecb_sbc:65c816_ecb_sbc [2017/12/25 15:33] (current)
borutk
Line 96: Line 96:
 <font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​BorutK has been building the 65c816PCB and has made the following observations while bringing his board up . .</​font>​ <font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​BorutK has been building the 65c816PCB and has made the following observations while bringing his board up . .</​font>​
  
-  * <font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​U16 gal20v8 and U7 74xx14 must be fast! In order to get the board to run Borut needed a 7ns GAL in U16 and U7 needed to be a 74F14 or 74ALS14.</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​There was a problem where sometimes U5 would latch in some spurious high addresses which</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​should</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​not</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​be</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​there</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​and</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​that</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​screwed</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​up</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​the</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​ram writes. The scream test would work, but 1 out of 3 ram accesses would be wrong.</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​The reason was that U7E which inverts the CPUCLK to latch the high addresses was delaying too much. WDC</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​datasheet</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​says</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​that</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​BA</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​will</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​hold</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​max</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​10ns after the clock flank goes high.</​font>​+  * <font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​U16 gal20v8 and U7 74xx14 must be fast! In order to get the board to run Borut needed a 7ns GAL in U16 and U7 needed to be a 74F14 or 74ALS14.</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​There was a problem where sometimes U5 would latch in some spurious high addresses which should not be there and that screwed the ram writes. The scream test would work, but 1 out of 3 ram accesses would be wrong.</​font><​font 11pt/​Calibri,​sans-serif;;​inherit;;​inherit>​The reason was that U7E which inverts the CPUCLK to latch the high addresses was delaying too much. WDC datasheet says that BA will hold max 10ns after the clock flank goes high.</​font>​
  
 Also, he suggested the following if we ever do a respin of the board Also, he suggested the following if we ever do a respin of the board
boards/sbc/65c816_ecb_sbc/65c816_ecb_sbc.txt · Last modified: 2017/12/25 15:33 by borutk
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