- Announcement about May 10th, 2018 update and your password.
P2 SD Card Boot code for ROM
I just posted code and sample output on the Prop2 FPGA Files thread.
Please post any SD card test results here, to save clogging the FPGA thread.
Note that I am not using any SmartPins or complex instructions. If all proves successful, as it did in P1, then we have the basis for the simple boot code (excluding the actual checksum validation and pass for execution).
This code follows the latest SD Card info, and fixes for the issues found in P1. I have not found card that will not work.
This code tests for FAT32, and if found, it locates the VOL label sector.
My thoughts are that booting from SD Card would be as follows (slightly different to previous discussion, but permits support of FAT32 as an option as well as MBR booting)....
1. Check for SD Card Type (SDHC as a minimum)
2. If FAT32, then find VOL sector, and locate a file called "P2BOOT.BIN". If found, read the first 512 byte sector into COG-0 and execute it.
3. If not FAT32 or P2BOOT.BIN not found, then read MBR (sector 0) into COG-0, verify checksum of bytes 128-383 (256 bytes) = "PROP" (or whatever Chip decided), and if so, JMP #128 to execute loaded code.