SDRAM is both hard and incompatible from FPGA board to board. Use scratchpad RAM instead. - Githubissues

KestrelComputer / kestrel

The Kestrel is a family of home-made computers, built as much as possible on open-source technology, and supporting as much as possible the open-source philosophy.

http://kestrelcomputer.github.io/kestrel

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SDRAM is both hard and incompatible from FPGA board to board. Use scratchpad RAM instead. #253

Closed sam-falvo closed 7 years ago

sam-falvo commented 7 years ago

e emulator changes

[x] Allocate 256KB of scratchpad memory in address range $x0xxxxxxxxxxxxxx.
[x] Relocate MGIA's frame buffer to address $10000 (64KB).
[x] Rebuild eForth with new configuration.
[ ] K3UG documentation updates.
[ ] Switch emulated CPU to U-mode operation.
- [ ] Get rid of unnecessary CSRs.
- [ ] Move interrupt bits to U-mode positions.
- [ ] Implement ustatus, utvec, ubadaddr, etc. instead of their m* counterparts.

Extra credit:

[ ] Implement an "expram" configuration setting to let the user set how much additional SD RAM.
[ ] Allocate expansion RAM in address range $x5xxxxxxxxxxxxxx (I think)

Pre-requisite for kestrelcomputer/polaris#8

This provides an initial, cold-boot memory map of:

From	To	Description
00000	0DFFF	BIOS state.
0E000	0FFFF	BIOS stack.
10000	1FFFF	MGIA Frame buffer (640x480, monochrome)
20000	3FFFF	Free for use by boot-loaders, etc.

Of course, anything beyond $3FFFF is similarly available for boot-loader use too.

sam-falvo commented 7 years ago

No longer relevant; does not apply to icoBoard Gamma configuration.