Question

[OK1FSX]

Hello dear NaturalTangent, thanks for your multicart design. This is not an issue, I only would like to ask. What do you think how critical is the material of connector surface GOLD/TIN and also the connecting of memory chip SOLDERED/SOCKET?? I can not make my multicart work and I am looking for the reason. I have PCB from JLCPCB with tin surface and chip is placed in socket. Maybe this is the reason. What are your experiences? Thank you very much for reading, any advice would be appreciated. Thanks and regards, Tomas Kozeluh

[NaturalTangent]

Hi Tomas. I didn't specify any special material when I had them fabricated - I went for the cheapest option. I guess it depends on how often you intend to insert and remove it.

The DIP switch positions may be important depending on the size of the EPROM you have used. I used a 39SF020 that I had lying around. Since it was smaller than the max size supported I recall that I had to set some of the (upper address?) DIP switches high or low (I can't remember now).

Assuming I've left the switches in a working position since the last time I used it, they are currently set as follows (with the 39SF020).

JP1=open
JP3=open
JP2=closed
JP4=closed

1=off
2=off
3=on
4=on
5=off
6=off
7=off
8=on

Looking at the cart with the connector at the top and DIP switches at the bottom (off is down, but I may or may not have soldered the switch pack upside down - I can't remember).

Hopefully some of that will help!
Andy

[OK1FSX]

Thank you very much Andy, I'll post a message when I find out what I'm doing wrong. Have a nice day. Tomas

[OK1FSX]

Dear Andy and multicart builders, be aware small bug in the schematic. When using SST39SF020 as in the schematic described, the pin #31 is not A18 but WE# (write enable) which MUST be always in HIGH state when reading. When #31 pin would be LOW, multicart will not work. Now my multicart works fine and I am happy :-), have a nice day. Tom OK1FSX

[NaturalTangent]

Glad you figured it out! :)