Difference between revisions of "Category:84PCE:RAM:By Address"

Revision as of 09:16, 30 September 2016

See also list of RAM areas by name.

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The eZ80 has a 24-bit linear address space. Layout:

• 000000h: Start of flash. The first 128 K are locked boot sectors. The first 8 are divided into 8 K sectors, all of which are locked. The certificate is now a single 64 K sector, so I hope you don't crash while rebuilding it.
• 000066h: Flash exception handler. Write-to-flash without permission triggers the non-maskable interrupt to fire.
• 00007Eh: Hardware/Emu flag: This byte indicates whether the ROM is a hardware ROM or emulator.
• 000080h: Start of boot code jump table.
• 020000h: Start of OS.
• 0C0000h: Start of user archive.
• 3B0000h: Certificate.
• 3C0000h: Temp RAM backup, on newer versions of TIOS debug output is also written here.
• 3E0000h: Temp RAM backup.
• 3F0000h: Temp RAM backup, temp certificate backup, swap sector.
• 400000h: Can be setup to mirror flash, but usually unmapped.
• 800000h: Always unmapped.
• D00000h: Start of RAM. 256 K.
• D1A87Eh: Top of the SPL stack.
• D1A881h: Start of UserMem.
• D40000h: Start of VRAM. 320x240x2 bytes = 153600 bytes.
• D65800h: Unmapped memory.
• D80000h: Mirror of D00000h.
• E00000h: Start of memory-mapped I/O address spaces.

SafeRAM Areas:

• D031F6h: pixelShadow - 8400 bytes
• D052C6h: pixelShadow2 - 8400 bytes
• D07396h: cmdPixelShadow - 8400 bytes
• D09466h: plotSScreen - 21945 bytes
• D0EA1Fh: saveSScreen - 21945 bytes
  • Note that the above is contiguous, which provides a total linear free space of 69090 bytes of RAM.
  • pixelShadow2 is the most stable; and is a viable option for testing TSRs and hooks.

More SafeRAM Areas:

• D006C0h: textShadow - 260 bytes
• D0232Dh: cmdShadow - 260 bytes

Also, if you do not wish to use the LCD cursor (This is not RAM, but can be used as scrap)

• E30800h: cursorImage - 1024 bytes