Unicart64 - The FPGA based cartridge for Commodore 64

  • 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

    I agree and believe you I will be suprised :D .



    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:)

    This is really interesting ... I will check it. This is possible future way I would like. Only 2 things. It is not probably pin compaible and I would need another regulator for 1.8V. It means redesign of the board. But yes it is a way ... :thumbup: .

    did not try to use dram before but, someone already done this,interesting
    hackaday.com/2013/10/11/sdram-controller-for-low-end-fpgas/
    github.com/enjoy-digital/litedram

    I know there are such examples for DRAMs, but I have decided already ... NO DRAM at all :thumbsup: . You know this is not only about refreshing but also I have no free IO pin in FPGA for PLL etc. etc. I would need larger FPGA and this leads into different situation. All such question I had at the beginning of this year and I have decided yet. :D But, Thanks for your ideas!


    And ... THANK YOU ALL for your interrest.
    Und ... Danke allen für Euere Interesse !

  • I know there are such examples for DRAMs, but I have decided already ... NO DRAM at all :thumbsup: . You know this is not only about refreshing but also I have no free IO pin in FPGA for PLL etc. etc.

    A DRAM needs less address lines than an SRAM of the same capacity becuase they are multiplexed.

  • Update info, Firmware UC64190124 (24.1.2019):

    • Final Cartridge 1/2 - bug solved, now fully working
    • Final Cartridge Plus, solved NMI line 0->1 in freezer mode, working
    • Final Cartridge 3, extended to TFCIII+ up to 256 kB
    • RAM based cartridges REU, RamCart, GeoRAM can be started with/without reset pulse
  • And ... I need write some common recommendations:


    Please, don't touch buttons by your fingers when it is up & running !!!
    It is recommended to use e.g. plastic pen etc.
    Sometimes there are more lightnings than you think .. :D .


    Don't manipulate with micro SD card in the board when it is up & running.
    The C64 must be turned off.


    And one hint:
    If the Run/Stop key is pressed during the C64 power on, it will boot from KERNAL.
    Otherwise it will try to boot from microSD card.

  • Hi retroguys,


    Please, did you have a chance to test Unicart64 board already ?
    I need your feedback, pls. follow instructions, for details, see previous posts (user guide).


    Don't forget format your SD card to FAT32 filesystem at the beginning. The FAT32 is important.


    After the start:
    Button-A (left): it is general reset (boot from SD card)
    Button-B (middle): it is KERNAL reset, but if you press Button-C, this Button-B will reset current crt from current slot (EasyFlash)


    1) I need to know, if Run/Stop key at C64 start up is working.
    2) I need to know, if setboot.prg shows green/red border color (OK/error status).
    3) I need to know, if bootfile "c64-boot.prg" is started. The commander will show you files on your SD card.
    4) Try to start some .PRG files directly from your SD card using commander.


    Pls., report me all issues visible on your machine, whatever it is. Every bug, problems, whatever.


    Thank you very much. Your feedback is very important for me.
    Regards,
    Peter

  • Explanation:
    I plan to have "open board" available for everybody to develop FPGA firmware and/or Software.


    I will provide for free my FPGA FW, software, but if you don't like it you will have a chance to develop your own.


    I'm preparing the documentation, but it takes time. For now is important the basic things are working.
    I plan to slowly update the docu and publish it.
    Please, it is under the development still. I plan to move it forward.


    Note: Every board was tested on my C64 machine using my micro SD card before the sending to the guys.
    Everything was running correctly.

  • So, my board has arrived, Thanks.


    My results:


    1. working
    2. green border
    3. screen turns completly red, no message, nothing else happens. I used your modified file from package. sd card is 8GB / FAT32 / MBR. No other files than c64-boot.prg on the sd card.
    4. no test because of 3.


    Edit: copied several prgs to sd card, no change (red screen)

    n paar Cevies, n paar Amigas, n paar FPGAs, n Haufen Zubehör und viel zu wenig Zeit...

    Edited once, last by wolfme ().

  • Oh, it does fancy things with the character color when i start with run/stop pressed.
    When i move with cursor over chars on screen, they change color randomly.
    And large floppy listing (from my SD2IEC) changes char color, too.