Is there a way to program an epcs prom in circuit without using Nios?

It's fairly easy using a nios design, and probably more complicated to do from HDL.

One way from HDL - instantiate an instance of the Serial Flash Loader (SFL) megafunction in your design. When you build the megafunction, enable the box for "Share the ASMI interface with your design".

Then you'll have to work out the logic to drive DCLK_IN, nCSO_IN, ASDO_IN, nOE_IN, and ASMI_ACCESS_GRANTED (inputs to the megafunction), and use DATA0_OUT and ASMI_ACCESS_REQUEST. I don't know if Altera provides much info on how to use these.

I found that putting epcs_controller in my NIOS system and using the epcs_commands.h commands was fairly simple. One hickup was that it was necessary to call epcs_write_enable before calling epcs_write_buffer, even though epcs_erase_sector didn't require that - it makes the write_enable call itself.

\chuck