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Great idea to compare like-for-like with the only difference being latency (80ns vs 60ns). The reduced latency of 60ns does show improvement over 80ns (see below). Both benchmarks were done with all the same registers and the same frequency of 40MHz (except of course the 1 bit change for the...

OK I ran an initial benchmark with extensions disabled on my LC475/Q605 with v092 of the ROM. Remember this version has the onboard chips disabled. I borrowed that hack from @Mustermann, and I also borrowed his LC475SetCPUClock program. But I made one change to the Config register bits for...

This is just such a great thread, I wanted to link it to this other one regarding ROM modifications. I borrowed from @Mustermann the hack to skip the onboard RAM and the LC475SetCPUClock program. However I made one mod to this program, and that was to set bit 3 from 1 to 0 for the Config...

Here is the "proof" that the v092 ROM for the Q605/LC475 (above) bypasses counting RAM bank 0 (slow onboard chips). Over the next couple days I am going to work on the Config register to see if I can get the MEMCjr to address the RAM at 60ns with the onboard chips disabled. (If you read the...

@opualuan @MrFahrenheit @qubitz Take a look at this other thread linked below. I took these hacks from @Mustermann and implemented them into the ROM I have been hacking. For the LC475/Q605 I am calling this "version 0.92."...

I am not sure if @Mustermann is around anymore. But he had a pretty neat thread I linked to below regarding disabling the slow (70ns) onboard RAM for the LC475/Q605. https://68kmla.org/bb/index.php?threads/lc475-disable-onboard-ram.49016/ So I took his lead and implemented this in what I am...

Attached is ROM checksum 42 0D BF F3. Any of the machines listed below should be shoe-in candidates for testing: Quadra 700 Quadra 900 I currently do not have a Q700, but one is in the mail. So I did my testing of this modified ROM and disk driver on a IIsi. Stay tuned for more ROMs with...

You might want to run MacsBug, and check to see what drives or drivers are loaded. That might help you narrow this down.

Just to point out, you can easily change the size of the disk image on these ROMs if you do not have an 8MB SIMM. Just change the following offset to the disk size you will be using, and append a different disk image. I will write up an instruction manual soon :) offset 61010 = ROM/RAM disk...

Attached is ROM checksum F1 A6 F3 43. Any of the machines listed below should be shoe-in candidates for testing: Quadra 610 Centris 610 Stay tuned for more ROMs with these same hacks. If you have any special requests, please let me know.

Agree with the all the comments. @Mustermann would be very interesting in seeing your edited ROM if you would be willing to share.

@JDW had a really good idea regarding this thread. This was to be more verbose in the machine models that could be used for each ROM. So on the attached file, this is ROM checksum FF 74 39 EE. Any of the machines listed below should be shoe-in candidates for testing: Quadra 605 LC 475 LC 575...

I don't have a Q650. But I could work up this same list of hacks and ROM/RAM disk for that machine if you'd like to test it? Do you have an 8MB SIMM? I'm going through my notes to see if I can make sense of what we ran into specifically. I seem to remember issues with some ROMs that might use...

I have a C/Q610 as well. So I have the same ROM ready to go for that specific machine. Right now it has a 7MB disk image appended, so if you could find your 8MB SIMM that would be ideal. I'll post the ROM for the C/Q610 tomorrow. I could look at adding a 1MB disk image instead, but that would...

I do have these same changes prepped for the other 1024KB ROMs. @olePigeon what do you have available? I will see about getting that ROM prepped to share here too.

For those with LC475/Q605-type Macs (ROM checksum FF 74 39 EE), a working SIMM slot, a SIMM programmer, and an available 8MB SIMM..... I would appreciate feedback on the attached ROM. Firstly, thanks goes to @JDW @Jockelill and @WillJac for doing some initial testing and providing feedback. An...

OK for the fun of the community, here is the mock code I threw together for this. I'm thinking of having a specific offset set aside in ROM to trigger this. So if the appropriate offset = 0x01, then run this routine to set the mouse tracking and volume. When burning the ROM, users could...

And interestingly, when you call WritePRAM (0xA038), the system really uses the WriteXPRAM (0xA052) trap to write the 20-bytes of PRAM from low memory back to the clock chip.

I used to collect these darn AOL disks. I had like 100 of them in a drawer at one point, back when floppies were a big thing. Like Blockbuster, this is the end of an old era. I look back fondly on the sound of an analog handshake and the world that opened up to me in the mid 90's.

With the "old" base PRAM, I think Apple's intent is for us to update the value in low memory directly, then call the WritePRAM trap (notice this is not WriteXPRAM). It appears that the WritePRAM trap will essentially copy all 20-bytes of PRAM from low-memory back into the clock chip. Certainly...