Hub Memory Map - rosco-pc/propeller-wiki GitHub Wiki
Hub memory contains 65536 bytes (or 32768 words, or 16384 longs). Hub Ram uses half of this space ($0000-$7FFF) and ROM uses the other half ($8000-$FFFF).
| $0000 | LONG ClkFreq | This value is created by the spin compiler, and is equivalent to the system variable _CLKFREQ that may be set in the Spin Top Object. If a user program changes the frequency using the CLKSET command, it should also update this value. Default is 12,000,000 which is the approximate frequency of RCFAST mode. |
| $0004 | BYTE Clk | Equivalent to the system variable _CLKMODE that may be set in the Spin Top Object. If a user program changes the frequency using the CLKSET command, it should also update this value. Default is 0 which corresponds to RCFAST mode. |
| $0005 | BYTE Checksum | -TBW- |
| $0006 | WORD TopObjectBaseAddress | Start address of the top object in a spin program. PropTool currently always sets this to $0010 |
| $0008 | WORD VariablesBaseAddress | Start address of Spin variables. |
| $000A | WORD StackBaseAddress | Start address of stack. Stack grows upwards from here. |
| $000C | WORD Main | Address of first PUB method in top object. Program execution starts here. |
| $000E | WORD InitialStackPointer | Initial value of stack pointer. Live stack pointer is kept in the interpreter Cog RAM, so this value doesn’t get updated. |
| $0010- | Top object | Usual start of top object. |
| $8000-$BFFF | Character Set | 256 characters of 16x32 (width x height) pixels in two colours. In fact that isn’t the whole truth. The “characters” numbered 0, 1, 8, 9, 10, 11, 12, 13 are really eight patterns of 16x16 pixels in four colours. A fancy video driver can give a coloured background to a rectangle of 32x16 characters, and use the 16x16 patterns to add beveled edges and corners to the rectangle. The patterns also provide underlines, overlines, and triangular marks inside the corners, made visible or invisible by changing one of the four colours. |
| $C000-$CFFF | Log Table | 2048 word values |
| $D000-$DFFF | Anti-log Table | 2048 word values |
| $E000-$F001 | Sine Table | 2049 word values |
| $F002-$F003 | Unused (padding) | The sine table contains word values while the Spin interpreter and boot loader are stored as long words. They must be aligned as described in Hub Ram. The change in alignment creates this unused space. |
| $F004-$F7C3 | Spin Interpreter | To start the Spin interpreter, a cog is initialised with $F004 as the entry point and PAR pointing to $0004. The hardware copies 496 long words from this address range into the new cog’s Cog Ram. The hardware loads the rest of the Cog Ram with zeros. |
| $F7C4-$F7FF | Unused | These long words are part of the space allocated for the Spin interpreter but are not copied. |
| $F800-$FFBF | Boot Loader | On reset, the hardware copies 496 long words from this address range into cog 0’s Cog Ram. $FBB4-$FFBF (cog $0ED-$1EF) are copied but the boot loader doesn’t use them in any way. $FF00-$FF5F (cog $1C0-$1D7) contain a copyright notice. |
| $FFC0-$FFFF | Unused | These long words are part of the space allocated for the boot loader but are not copied. |