Does Altera support hybrid external memory interfaces that wrap between VIO and HIO on Stratix III devices?
Solution For maximum performance, Altera recommends that data groups for external memory interfaces be grouped on a single side of your Stratix® III FPGA. However, Altera can support interfaces with data groups that wrap between verticle and horizontal (hybrid); the speed at which the hybrid memory interface can run is given in table 1-26 of the Stratix III Handbook Volume 2, Chapter 1 DC and Switching Charateristics of Stratix III Devices (PDF). x36 emulation mode for the F780 and F1152 packages do not support hybrid mode. This was not supported in 7.2 and is not currently planned for support in a future revision of Quartus® II software. In Quartus II software version 7.2SP3 and earlier, this functionality was allowed natively but in Quartus II software version 8.0, you will get an error message similar to the following: “Error: Cannot place DQ I/O “mem_dq[nn]” to I/O location Pin_Nn since its memory interface I/O group cannot be placed” This error will incorrectly prevent hybrid inte
