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E‐14HardwareReferenceManual www.picocomputing.com PicoComputing,Inc.
11
FlashMemory
ThePicoE‐14comesequippedwithatleast64megabytesofFlashROM.TheFlashROMisdividedinto
512sectorsthatcanbeerasedindependently.MostofthespaceontheROMisreservedfortheuser.
TheFlashROM’saddressbuscanbecontrolledbyeithertheTurboLoader
ortheFPGA,butnotboth.
Duringpower‐uporreboot,theTurboLoaderisincontroloftheFlashROMAddressbus.Atallother
timestheFPGAisincontroloftheaddressbus.
Figure2
TypicalFlashROMAllocationTable:
Byteaddresses Description FlashSectors
0x00000000‐0x0000FFFF TupleDataandconfigurationmanagement 0
0x00010000‐0x0006FFFF PrimaryFPGAImage 1‐6
0x000A0000‐0x000FFFFF BackupFPGAImage 7‐12
0x000D0000‐0x0012FFFF SecondaryImageincludingbootloader 13‐19
0x00140000‐0x01FFFFFF OtherFPGAimages,executablesanddatafiles 20‐511
TheFlashROMhasasimple,openfilesystemthatallowstheusertostoreFPGAimages,ELFbinary
files,orotherdata.TheprimaryimageisusedtoboottheFPGAinitially,andthebackupimageisonly
invokediftheprimaryimagefailstoloadcorrectly.ExecutablefilesareinELFformatandareloadedby
aloaderwithinthesecondaryimage.Theprimaryimagecaneitherloadthesecondaryimageorpause
forthePCtoaccessandmanagethefilesystem.