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Old 01 December 2018, 14:19   #1
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Join Date: Dec 2010
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Lightbulb TurboMMU040+ released!

TurboMMU040+ 1.7 ©SpeedGeek 2019

TurboMMU040+ is an MMU tool to maximize the MMU performance
of most* 68040 and 68060 libraries. The MMU is a most excellent
and valuable feature of advanced 68K CPUs. Unfortunately, it's
usage does not come without any performance loss. How much
performance is lost depends on many factors, but this tool
deals specifically with the MMU configuration factors.

- Enables 8K page mode MMU operation!
- Converts existing 4K page tables to 8K page tables
- Does NOT increase memory usage for MMU tables
- Enables (optional) ITTx management for 4GB of address
- Uses 68040/060 library detection code
- 100% Assembler code

- Amiga with 68040 or 68060 CPU and MMU
- 68040.library or 68060.library

The 8K page size provides a 2x increase in the address space
which resides in the ATC. When a page address "Hits" in the
ATC it provides a "Zero" wait state address translation.
When a page address "Misses" in the ATC the MMU performs a
table search in memory to find the page address. Hence, many
wait states are incurred which result in a performance loss.
Both the 68040 and 68060 have a 64 entry ATC so 64 x 4K =
256K and 64 x 8K = 512K.

The ITTx registers manage the instruction page descriptors
for a 16MB - 4GB size of address space. They are typically
disabled but may be enabled for part of the address space by a
few libraries. TurboMMU040 optionally enables it for the full
4GB of address space. This effectively bypasses the MMU
and provides "Zero" wait state performance for all instruction
translations. The ITTx usage trade off is the loss of the of
the performance benefit (if any) from remapping the Kickstart
ROM(s) into Fast memory. Also, if the library has already
enabled the ITTx you may want to keep the default settings.

Systems configured with a DMA driver MUST install
FastCache040+ before using this tool! Otherwise, the
CachePreDMA/PostDMA API of the 68040/060 library will assume
the 4K page size and fail to modify the correct pages
resulting in eventual data transfer errors!

Failure to disable or unmap MMU remapped Kickstart ROM(s)
will result in a loss of memory which can NOT be reclaimed
after conversion to 8K pages (YOU HAVE BEEN WARNED!).

Attempted usage of this tool with existing 4K MMU tools is
VERY risky! Some tools will check the page size and safely
exit, but others will just assume the page size is correct
and proceed to crash your system! Likewise, libraries which
have a built in API (e.g. Phase 5) should be used with

This tool does NOT always provide an identical memory map to
the original. Specific cases when mapping will change are:

1) MMU remapping of the Zero page area is 4K aligned (MMU
remapping is disabled).
2) SRP table differs from URP table (URP table replaces SRP
3) The Kickstart MMU remap warnings have been ignored (All
physical ROM addresses are restored).

*Compatibility support for most 68040 and 68060 libraries does
NOT mean all of them!

The executable file name excludes the "+" character to avoid
problems with the Amiga Shell. See TurboMMUtools.txt for info
on the initial support tools.

Added MapConTM060 1.0 to archive. MapConTM060 supports the
very proprietary TekMagic 68060.library. See MapConTM060.txt
for more info. Since v1.5 TurboMMU040+ allocates 16KB of RAM
to handle the (few) libraries which use 4K aligned remapping
of the $FFFF8000 space.

v1.0 - First release
v1.1 - Added code to keep the Zero page remapping if it meets
the 8K alignment requirement (So you got a 50/50 chance)
v1.2 - Added code to compare Page table address at 8K blocks
vs. 4K blocks. This might improve indirect mapping accuracy only since direct mapping is always converted to the physical address.
v1.3 - Updated code to allow indirect mapping of the "Extended" Zero page area. Added NOITTx option so the libraries default ITTx settings can be maintained.
v1.4 - Added code to detect and report FastCache040+ as a
helpful reminder.
v1.5 - Added code to keep direct remapping of $FFFF8000 space for libraries which don't use indirect. Lha_68K gets a psuedo Enforcer hit for relying on MMU remapping here.
v1.6 - Added code to disable the DTTx registers. This is a quick fix to support the very proprietary Apollo 68060.library. Apollo gets away with the default DTTx enable only because the SCSI controller doesn't use DMA.
v1.7 - Fixed typo bug for ITTx options. Now shows 4GB size.
Attached Thumbnails
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Attached Files
File Type: lha TURBOMMUBENCH11.LHA (1.8 KB, 77 views)
File Type: lha TURBOMMUTOOLS13.LHA (4.3 KB, 48 views)
File Type: lha TURBOMMU040+17.LHA (4.6 KB, 36 views)

Last edited by SpeedGeek; 08 February 2019 at 14:56.
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