[sv-bc] $readmemb and always_latch/always_ff

I encountered a compatibility difference between two major simulators today
during a training class.  One simulator allows a testbench to use $readmemb
to load a RAM that was modeled using always_latch for the RAM write logic.
The other simulator gives a compilation/elaboration error, saying that
$readmemb is illegal, because it is a second procedural block writing to the
memory array.

Which simulator is correct?  While it is true that
always_comb/always_latch/always_ff do not allow multiple procedural blocks
to assign to the same variable, I do not believe that $readmemb is a
"procedural assignment".  I have a group of students interested in knowing
if always_latch and always_ff can be used to model RAMs.  Any thoughts from
SV-BC would be appreciated.

Stu
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Stuart Sutherland
stuart@sutherland-hdl.com
+1-503-692-0898