Posts by zmaj

  • Unicart64 - The FPGA based cartridge for Commodore 64

    Quote from Peto74

    Answer:

    • REU (for demos, I have "only" 8MB, I wanted 16MB at the beginning :D )
    • EasyFlash loading images into SRAM (1 slot = 1 MB)

    I had also idea to use the PRAM (not sure if this is correct name ...) instead of SRAM. This is significantly cheaper. There is DRAM inside, and this stupid autorefreshing is hidden , interface is like SRAM. But, unfortunately, I could not find 8/16 MB.

    In development I would also use sram :) but for production one want to make any cost reductions,
    ie if you do of 50 pcb one single ic ram could cost me up to 10E per board,
    but if I put 8 chips instead of one, as it is more available, it cost cheaper ie 3.78E for 8 chips per pcb,
    and you would be surprised what you can put today on back side of 6.5x5cm pcb :)


    Pseudo SRAM is good choice winnbod make them 128Mb and 256Mbx16 @1.8V, they are also known as cell ram,
    these rams are low powered and even dram is refreshed only where is content in cells:)


    Do not be afraid if it is x16 a) you can use only half of it b) you can bank it, ie half for REU half for EF
    after all you will interface it with FPGA :)


    did not try to use dram before but, someone already done this,interesting
    https://hackaday.com/2013/10/1…roller-for-low-end-fpgas/
    https://github.com/enjoy-digital/litedram