SD Card

https://oshpark.com/orders/3WKmUcwT

https://web.archive.org/web/20221127110555/https://wiki.hakchi.net/Adding_an_Internal_SD_Card

https://github.com/going-digital/sdnes

PF0  SDC0-D1   8
PF1  SDC0-D0   7 
PF2  SDC0-CLK  5
PF3  SDC0-CMD  2
PF4  SDC0-D3   1
PF5  SDC0-D2   9
VCC  SDC0-VCC  4
GND  SDC0-GND  3 (and 6?)

https://electronics.stackexchange.com/questions/624510/schematic-to-work-with-an-sd-card

https://e2e.ti.com/support/microcontrollers/msp-low-power-microcontrollers-group/msp430/f/msp-low-power-microcontroller-forum/215721/do-we-need-pull-ups-in-spi-with-sd-card

The 'SanDisk SD Card. Product Manual. Version 2.2' says that; "The extended DAT lines (DAT1-DAT3) are input on power up. They start to operate as DAT lines after the SET_BUS_WIDTH command. It is the responsibility of the host designer to connect external pullup resistors to all data lines even if only DAT0 is to be used"

https://forum.arduino.cc/t/why-the-pullups-on-sd-card-pins/695552/2