(DIY) C64iSTANBUL
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Sep 28,2020
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C64 CHARACTER GEN. ROM REPLACEMENT ADAPTER (COMMODORE)

This ROM adapter is suitable for replacing Commodore64 Character Generator ROM (For replacing 901225-01)
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Published: Sep 28,2020
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Topic
DIY Electronics
Computers & USB
Programmable Logic Projects
901225-01 901460-03 character generator rom 901225 replace 901460 replace 901460-04 901225-02 901225-03 901225-04
  • Comments(25)
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  • Hi everyone, I bought some of these pcb to replace the original 901225-01, but I can't get them to work... I assembled the board following the instructions, using the required components. I wrote a ST M27C64A eprom with two 4k CHAR .bin, I didn't use any jumpers, but once turned on the screen remains blue with no writing. Can anyone tell me where I'm going wrong? Thanks everyone!

    Oct 08,20241 Comments
    (DIY) C64iSTANBUL 2024-10-08 12:23:32Reply

    Hello Demidio Siri, can you please send photos of your circuit taken from different angles and binary eprom file to c64istanbul@gmail.com?

    Reply

  • Hi apologies if this is a very basic question - what are the jumpers for, how do I determine which jumpers to bridge?

    Jan 19,20231 Comments
    (DIY) C64iSTANBUL 2023-01-19 07:13:00Reply

    Hi, Jumper use is optional, not mandatory. Jumpers can be used to replace different Character ROMs in different languages, this is mostly done by replacing the Character ROM with Kernal ROM and requires a special keypad. If only the faulty character ROM is to be replaced, you do not need to use Jumpers. Thanks for asking.

    Reply

  • With a small mod, this adaptor can also work as a VIC-20 Character ROM replacement. One small trace cut and one jumper wire. See this thread for more discussion: http://www.melon64.com/forum/viewtopic.php?f=27&t=14474

    Jul 22,20212 Comments
    (DIY) C64iSTANBUL 2021-07-22 12:44:23Reply

    Thank you very much Nama.

    (DIY) C64iSTANBUL 2022-11-02 07:14:36Reply

    https://www.pcbway.com/project/shareproject/COMMODORE_VIC_20_CHARACTER_ROM_REPLACEMENT_ADAPTER_MOS_901460_03_2026df67.html

    Reply

  • it can't properly work on VIC20

    Oct 23,20204 Comments
    (DIY) C64iSTANBUL 2020-10-23 02:54:58Reply

    Thank you cermassi. Did you watched videos? is it the same problem? I do not have a vic-20, Mr Eddie Bannister from AUSTRALIA tested on vic-20 and recorded videos. Can you please send an e-mail to me c64istanbul@bikom.com

    Mr Eddie Bannister 2020-10-23 09:03:39Reply

    Hello cermassi and C64iSTANBUL, Well spotted! I will make the necessary alterations to the boards I have and test the PCB's in the VIC20 again. It should not be a difficult change. I will post what I have done with details so people can do the modification easily themselves.

    (DIY) C64iSTANBUL 2021-07-21 08:22:39Reply

    https://youtu.be/f_DzuPC9OdU

    (DIY) C64iSTANBUL 2022-11-02 07:14:22Reply
    Reply@ Mr Eddie Bannister：

    https://www.pcbway.com/project/shareproject/COMMODORE_VIC_20_CHARACTER_ROM_REPLACEMENT_ADAPTER_MOS_901460_03_2026df67.html

    Reply

  • I just received 10 pcb from PCBway... I suppose that if you plan to use the adapter with a just a given ROM size, you only need one resistor and one jumper, am I right? But I'm not sure what the 4KB x 16 vs. 8KB x 8 pcb jumper serves for...

    Aug 17,20222 Comments
    (DIY) C64iSTANBUL 2022-08-17 02:55:08Reply

    This PCB is designed as 16x4KB. Because 4KB is enough for the character ROM. If it is desired to be used as 8x8KB, the line between the jumper must be cut and short-circuited to the 8KBx8 side and the resistor connected to the A12 line must be removed.

    Giovanni giobbi 2022-08-17 21:17:38Reply

    thank you. BTW where could/should I use a 8Kb for Char ROM?

    Reply

  • Works great!

    Jan 27,20211 Comments
    (DIY) C64iSTANBUL 2021-01-27 16:37:48Reply

    I like this photo, thank you Snoop67..

    Reply

  • i presume this will work for 901226 and 901227 as well ?

    Nov 23,20202 Comments
    (DIY) C64iSTANBUL 2020-11-23 23:35:14Reply

    Hello, This PCB is for 4KB Character ROM, 901226 and 901227 are 8KB. And I shared only Character ROM eprom file. If you want to use this PCB for 901226 and 901227 then you should modify; cut 4Kx16 and solder 8Kx8 side, and you should find and use correct 901226 and 901227 ROM files. Thank you.

    (DIY) C64iSTANBUL 2020-11-23 23:42:33Reply

    Or, you may use this PCB for 901226 and 901227 https://www.pcbway.com/project/shareproject/COMMODORE_64___KERNAL_TABLE__901227_KERNAL_ROM_REPLACEMENT_ADAPTER_.html

    Reply

  • I purchased some of these and they don't seem to work. Your positive pulls are floating. You have the switch on the same side as the resistors (Ground). I was able to get the board to work by passing through the resistor points and then I tied the top of the resistor points to VCC (pins 28/24).

    Oct 23,20204 Comments
    (DIY) C64iSTANBUL 2020-10-23 05:56:01Reply

    Thank you Thomas Sidener. I updated gerbers. Can you please send an e-mail to me c64istanbul@bikom.com

    Mr Eddie Bannister 2020-10-23 09:25:52Reply

    Well spotted! I will make the necessary alterations to the boards I have. Thank you.

    Thomas Sidener 2020-10-23 23:26:42Reply

    Thank You!!

    Thomas Sidener 2020-10-23 23:31:05Reply

    The new gerbers look spot on!!

    Reply
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