specgather.md

@@ -5,10 +5,38 @@ specification of the SPEC7.
 
 ## Under discussion
 
+### FMC HPC or LPC
+
+  - use case for HPC?
+  - Makes that large FPGA should be used
+
+### FMC connector
+
+  - Vadj 
+      - programmable IC, or just a few values and selection with
+        jumpers?
+
 ### FPGA family
 
   - Xilinx
-  - Kintex 7 vs Zynq
+  - [Xilinx All Programmable 7 Series Product Selection
+    Guide](https://www.xilinx.com/support/documentation/selection-guides/7-series-product-selection-guide.pdf#k7)
+
+<!-- end list -->
+
+  - Kintex 7
+      - FFG676 package allows 160T, 325T and 410T sizes on the same
+        footprint. Default 160T. 8 GTX Transceivers max (4 used for
+        PCIe, 2 for SFP, 2 left for FMC). Or use F\*B\*G package (allows
+        usage of 70T too)?
+      - Check if a 70T in FBG484 package can be used on footprint of
+        F\*B\*G676 
+
+<!-- end list -->
+
+  - Artix-7
+      - only if LPC
+      - low price
 
 ### SFP
 
@@ -21,12 +49,17 @@ specification of the SPEC7.
       - Could maybe fit if would make 2-slot card when optional
         heatsink/fan solution that extends it into the neighboring slot.
         Double decker would not work here though.
-
-<!-- end list -->
-
-  - Vadj 
-      - programmable IC, or just a few values and selection with
-        jumpers?
+  - Compact SFP (CSFP)?
+      - Has two bidi standard SFPs in one SFP module
+      - CSFPs have a little different pinout comparing to the standard
+        SFPs. Same mechanics as standard SFP
+        ([Wikipedia](https://en.wikipedia.org/wikis/Small_form-factor_pluggable_transceiver#csfp)).
+      - [Difference between SFP, bidi SFP and
+        CSFP](http://www.cables-solutions.com/differences-between-sfp-bidi-sfp-and-compact-sfp.html)
+      - [CSFP Delta
+        CSFP-33-A4K1DBT](http://www.deltaww.com/filecenter/Products/download/04/0405/BiDi/CSFP-33-A4K1DBT_S0.pdf)
+        (pinout on page 4)
+      - Check if use of CSFP would limit the use of standard SFP modules
 
 ### RAM
 
@@ -45,6 +78,11 @@ specification of the SPEC7.
     is a crazy idea, but it is nice to think that users can plug'n'play
     the SPUEC/SUPEC on their laptop :) (FV)*
 
+h3 PCB
+
+  - 10 layer PCB so that layout can be optimised for low-jitter
+    oscillator
+
 -----
 
 ## Accepted