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You are right, MC88916DW80.

There is a known limitation: MC88920 is involved into clock generation as well. Each MC88920 has an individual maximum frequency. This is usually around 36-40MHz. No matter what you set in Soft Overclock extension this frequency cannot be exceeded. System does not fail but frequency does not...

Additional logic might also be on an additional board. Additional board might be placed into ROM SIMM socket. ROM SIMM is connected to a socket at that board. Additional logic is on this board only. - No changed ROM SIMM design needed - Can be programmed in an external programmer without changes.

You are right, it might be an issue for an end user to add a flying wire from PDS to ROM slot. To avoid that another solution came into my mind: How about creating missing additional address lines from a latch (no additional wires outside of ROM needed): - In read cycle read entire 8MB...

Just my 2 cents: As you may know I own LC475 only. Those have MEMCjr build in. Documentation from MEMCjr tells: "A write to the normal ROM space, $4xxx xxxx with addressbit 22 set to '1' will cause the FLASHWE signal to be asserted" Based on that - you may assign 8MB to a 4MB ROM and are able...

You need to ensure that the chips are 5V compatible (check datasheet). Those are more common for FPM.

Check if you run at 32bit. In general Phiplis extersion should detect 24bit and show error Icon. I assume you don't use 24bit mode, as 132MB RAM doesn't make sense in 24bit mode. Did you try to clock-down to 20MHz or 25MHz? Maybe output of Clockometer is easier to use than Speedometer. 33 and...

Based on the discussion above I build an update of my PoC code: - Moved BIOSConfig from setregistermin() to setregistermax() Now UnknownMHz b0 = ? -> UnknownMHz b0 = 0 -> NewvalueMHz + b0 = 0 -> NewvalueMHz + b0 = Newvalue(accpording to NewvalueMHz) - Wrapped Code in SwappMMUMode So the...

The question i tried to raise was: You can not change clock frequency and BIOSConfig at once. So you have to choose: 20MHz + b0 = 1 -> 20MHz + b0 = 0 -> 40MHz + b0 = 0 or 20MHz + b0 = 1 -> 40MHz + b0 = 1 -> 40MHz + b0 = 0 Start and end are fine in both cases, step in between is not. Which is...

I am confused. BIOS in LC475 uses 20MHz: BIOSConfig = 0x01 25MHz: BIOSConfig = 0x01 33MHz: BIOSConfig = 0x00 40MHz: BIOSConfig = 0x00

register 0x50F1800 (BIOSConfig): While switching CPU speed this parameter can be set to the wrong value. Which is better (or less bad): b0 = 0 at 20Mhz or b0 = 1 at 40Mhz If it is like additional wait states, b0 = 1 at 40Mhz is better, because additional wait states are ok for a short time...

Things like that are what this thread is about, if I am right.

OSUtils was the missing information! #include <OSUtils.h> ... signed char busMode = true32b; SwapMMUMode(&busMode); was compileable without errors or warnings.

I tried to add this code but compiler throw an "function has no prototype" error. Seems I need to include something, but I do not know what. Someone can help?

You are right about $f7. So there is a typo at several copies of this code that can be found in the internet. I understood that the bit the ROM was changing b0 = 0 for BCLK > 25 MHz, 1 for 25 MHz or less according the clock resistors soldered on the 475/605. But what is this setting doing for...

I read some parameters to set for each frequency from ROM: BIOSConfig 0x50F1800 Thank you for the reply. ROM is writing only bit 0 to register 0x50F1800 (BIOSConfig) and register seems to be 8 bit long. I'm confused because things don't fit together. LEA...

GestaltID of overclocked 475 ist different from standard. Need to be in the list of the tool.

I read some parameters to set for each frequency from ROM: Configuration 0x50F0E030 RefreshInterval 0x50F0E034 FrameBufferConfiguration 0xF9800010 BIOSTimeout 0x50F18600 BIOSConfig 0x50F18000...

"343S0161" is a Gazelle as well. Performa 475 with 68LC040RC25 was able to clock up to 40Mhz. Everything above gave 40,21Mhz. Seems to be limited by MC88920.

In the last days I got an additional Performa 475 in my hands showing exact the results described above. Clock speed up didn't work. This Performa has "343S0161" soldered to the board. Based on the MEMCjr datasheet my first assumption was that "343S0161" is not a Gazelle but a DP8534. There is...