ZLoader Boot Process

ZLoader is burnt into the first two pages (32K) of the 512K flash device and runs on reset.

The startup sequence is as follows:

1. Run from SRAM

• Copy self into the first two pages of SRAM (32K)
• Enable paged memory
• Map the first SRAM block (page 20h) into bank 0 (lower 16K of Z80 space) and page 21h into bank 3 (top 16K).

2. Check boot options and either:

• Run the ZLoader command line
• Load and run the 'default' application from the Raspberry Pi attached to SIO port B
• Load and run the first SDCard bootable image

Step 2, choosing what to run, is determined by the two lowest order DIP switches. Values are:

• 00: Boot into command line
• 01: Boot from Raspberry Pi
• 10: Boot from SCard 1
• 11: Reserved for future use - currently boots into command line (as 00)