Software-only OVERCLOCK for LC475, LC575, Quadra 605

[Oelmuvun]

Interesting - how have you connected into the edge connector? Or is that the problem?

Edit - to get video out is a challenge though. You could potentially find an LCPDS Video card, but that isn't easy. Its easier with the LC 580 board because you can pick up a video adapter that goes in the GIMO port for not too much money, but there isn't a GIMO port on the 575.

Yeah, lack of the chassis harness is the issue, I've been tempted to solder some ribbons to the board but I'd still rather not resort to that. I have harnesses(but no cases) for my LC630 and PM6500 at least, so it's not the highest of priorities.

Anyway, keep up the good work.

 

[Opualuan]

Have LC475, ready for anything to max it out. Got a 40mhz 040, Haven’t ordered the MC88xx replacement chipset yet, but got a lot of practice with hot air rework this weekend, I’m ready! Interested to try the latest SW. control strip is very cool.

 

[phipli]

Have LC475, ready for anything to max it out. Got a 40mhz 040, Haven’t ordered the MC88xx replacement chipset yet, but got a lot of practice with hot air rework this weekend, I’m ready! Interested to try the latest SW. control strip is very cool.

Evening @Opualuan

Do you have a PowerPC upgrade?

The current latest published version is available for download here : http://stuffandnonsense.elephantandchicken.co.uk/?p=2519

I'll try to remember to keep that version up to date.

 

[phipli]

To the thread more generally:

I've still not been able to get significant support with PowerPC elements of the future version. One person got in touch but unfortunately they answer one out of three questions and then go silent for multiple weeks. I've made so little progress I've not actually even sent them the updated version yet (it is well over a month, if not two since they first contacted me - I'm worried they thought "testing" meant just getting a copy of something before other people, unfortunately, since I don't have access to the hardware I actually do really need answers to a few questions to work out what register settings I should be using). I'm thinking that there are so few PowerPCs out there that it would probably be better for me to just disable the PowerPC specific elements. At that point all that we're gaining is a different UI, so perhaps it is best to just stick to the current version 0.5.2 and concentrate on other things.

Truth be told, the Control Strip version is my favorite version and that has none of the fancy features

 

[JDW]

One person got in touch but unfortunately they answer one out of three questions and then go silent for multiple weeks.

Welcome to the club!

Whether it be in this hobby or at my day job, I find that once I ask more than one very specific and pointed question, the other person often gets overwhelmed. Then I need to play the follow-up game, which is a rather precarious game because if you follow-up too much, then the other person feels they are being hassled, further driving them into silence. But in the end, I find that persistence does pay off, even if a few feathers are inevitably ruffled in the process. Okay, well... maybe not in the case of my SE Reloaded Giveaway, where the winner still hasn't started the build yet after multiple follow-ups from me, but "you can't win 'em all."

As we say in Japan: 頑張ってくださいね！

Thank you for having made this overclock possible in the first place. You absolutely DO NOT get enough credit for your work on that control panel and extension and control strip module. But don't lose heart. Some of us really do thing your work is awesome. That's why I started this thread. More people need to know about the great things brilliant folk like yourself in this hobby bring to the table.

 

[phipli]

Whether it be in this hobby or at my day job, I find that once I ask more than one very specific and pointed question, the other person often gets overwhelmed. Then I need to play the follow-up game, which is a rather precarious game because if you follow-up too much, then the other person feels they are being hassled, further driving them into silence. But in the end, I find that persistence does pay off, even if a few feathers are inevitably ruffled in the process. Okay, well... maybe not in the case of my SE Reloaded Giveaway, where the winner still hasn't started the build yet after multiple follow-ups from me, but "you can't win 'em all."

At the end of the day, people in the hobby, I can't really complain. People have free will and no obligations. Work stuff, if it matters, either they need to be reminded why it has to happen and be given a deadline and milestones, otherwise it is getting reallocated to someone else. I've had it happen... I've been very frustrated, I've worked late having to do the stuff I asked someone to help me with... I'm sure we've all been there. Truth be told I've had more issues with managers allocated promised people to other projects between me bidding and winning work. With time you learn who you can trust and who you can't, and you earn emergency help credits by helping others so they are more willing to help you when the excrement hits the impeller.

 

[Byte Knight]

Cool project! I've got a Quadra 605 logic board in my LC III running a 68040 @ 40 MHz. Would this give me any speed boost on top of what I've already got?

 

[phipli]

Cool project! I've got a Quadra 605 logic board in my LC III running a 68040 @ 40 MHz. Would this give me any speed boost on top of what I've already got?

I've been able to run my 475 at up to 52MHz, but if you're already running at 40MHz I assume you have disconnected one of the pins on the 88920 and injected an external clock, or have a modified ROM? I'd need to know what exactly you've done to your machine to be able to answer for your specific case.

 

[Byte Knight]

I've been able to run my 475 at up to 52MHz, but if you're already running at 40MHz I assume you have disconnected one of the pins on the 88920 and injected an external clock, or have a modified ROM? I'd need to know what exactly you've done to your machine to be able to answer for your specific case.

I recall doing a resistor mod, but none of the mods that you're describing. Maybe it's really only running at 33 MHz...

 

[JDW]

Maybe it's really only running at 33 MHz...

Grab Download #4 and give Clockometer a try:

https://macintoshgarden.org/apps/newer-technology-disk

 

[phipli]

I recall doing a resistor mod, but none of the mods that you're describing. Maybe it's really only running at 33 MHz...

Yeah, if you just moved resistors, you wont be running at 40MHz. Electrically the computer has a 40MHz setting on the resistors, but there isn't a ROM entry, so the computer just doesn't boot. It doesn't even chime. I suspect you're running at 33MHz.

Like @JDW says, Clockometer will tell you.

 

[Byte Knight]

Yeah, if you just moved resistors, you wont be running at 40MHz. Electrically the computer has a 40MHz setting on the resistors, but there isn't a ROM entry, so the computer just doesn't boot. It doesn't even chime. I suspect you're running at 33MHz.

Like @JDW says, Clockometer will tell you.

Yeah, I was running at 33 MHz. Just installed the Software Overclock and the most I can get it up to is 37 MHz according to Clockometer, even when setting the control panel up to 50 MHz.

 

[phipli]

Yeah, I was running at 33 MHz. Just installed the Software Overclock and the most I can get it up to is 37 MHz according to Clockometer, even when setting the control panel up to 50 MHz.

Yeah, that sounds like you're hitting your head on the speed limits due to the MC88920. It seems to be the first limit you bump your head on if you're not limited by the CPU.

 

[Opualuan]

No ppc upgrade, keeping it 68k. I’ll give the new version a try. I have a few other logic boards I can test with.

 

[nottomhanks]

Just revisiting this, I have an overclocked 475 at 33Mhz, standard 575 at 33Mhz, and a Spicy 575. I also have the PPC 601 at 66Mhz and and I'd love to do a YouTube video with a shootout with tests of all three with graphics, floppy, serial, MIDI, and how far you can push the machines before they lock up. Might even be cool to do an infrared temperature time lapse with and without fans to see how cooling improves things. I recently acquired a 2nd PPC card at 66Mhz, but unfortunately some of the 68040 pins were bent/broken because the card became dislodged during shipping. (boo!). I think it can be repaired though. The Color Classic I picked up with the PPC Mystic setup has a nifty fan that was mounted above the heatsink, so I'm excited to get that going.

 

[JDW]

I did a lot of testing and I reported that to @phipli via PM. I also spoke to Mustermann, who is the gentleman who kick started the whole software overclock project.

Basically, what I found was that benchmark results were mostly the same as Spicy (on my 575 board) at the same clock speed, except for Video. Video scores were lower than Spicy when using Soft 475 Overclock. However, I found the magic sauce that really turbo charges everything, including video in the Advanced settings:

The secret sauce pertains to those Min and Max fields. If you're satisfied with the overclock performance and don't mind the slight video performance hit relative to Spicy, just leave those Advanced settings alone and enjoy what you have. That's really what Phipli recommends. But when I changed them from the default 3 down to 1, it was like Mad Max flipping on the Turbo Charger. I kid you not. Even with the clock speed set to 49.29MHz, with Min=Max=1, I suddenly started to get benchmark scores close to what I got with Spicy running at 51.6MHz. And let me tell you, Spicy didn't allow me to run at 51.6MHz for very long either.

Mustermann told me that the Min & Max fields "choose a set of values for different registers" and "influence wait states of RAM, VRAM and ROM.
If you choose a lower value, you may reduce wait states, operate RAM or ROM or VRAM out of specifications but may reach higher performance."

But it's important to keep in mind that I optimized my 575 motherboard for high overclocks using Spicy long ago, including:

1. Use of OS-CON caps for the lowest ESR (even so, Phipli said he can reach 50MHz even with Tantalum caps)
2. Replaced VRAM with a fast 60ns SIMM.

Fast VRAM matters a lot! But since I have that, the remaining bottlenecks are ROM and soldered RAM speeds. My soldered RAM is 70ns, and my 32MB RAM SIMM is 60ns.

It has been suggested that if the motherboard RAM could be removed or disabled, then the overall RAM speed would then be the RAM SIMM speed, which is 10ns faster. And in terms of the ROM, I soldered in a ROM socket on my 575 board and have an engineering sample ROM made by @Jockelill which is rated for 55ns. If that ROM could be reprogrammed to somehow disable the motherboard RAM (thereby eliminating the need to desolder it), then those remaining bottlenecks could be largely eliminated, possibly allowing a further boost to the maximum "sustainable" clock speed.

With that said...

• Serial ports stop working at between 44 & 45MHz.
• System 7.6.1 & OS 8.1 only boot reliably up to 47MHz, even when using Advanced Min=Max=1 settings.
• System 7.1 & 7.5.5 will boot reliably up to 49.43MHz. I often get a black screen at 50MHz or higher. But Phipli says 50MHz is table for him.
• If you have a IIe Card installed, you must disable 32-bit Addressing, and that disables the overclock.

I've been planning to do a video about the Soft 475 Overclock, but I've been busy with another video, and the amount of technical detail involved is pretty intense, so I still need to figure out how in the world I'm going to convey it to the world in an easy-to-understand way. But for now, I hope these added details will help some of you get more enjoyment out of the Software Overclock.

 

[nottomhanks]

@JDW , does that mean the software overclock requires 32 bit addressing stays on then?

 

[Nycturne]

@JDW , does that mean the software overclock requires 32 bit addressing stays on then?

Yes. At least with how the extension is currently written.

That said, rebooting System 7 is quick enough with a BlueSCSI or similar that I only disable 32-bit addressing when I want to use the IIe card.

 

[JDW]

@JDW , does that mean the software overclock requires 32 bit addressing stays on then?

Yes, it requires 32-bit addressing "to do the overlock."

You can switch to 24-bit addressing to run System 6 (well, not on my 575 board, but maybe on a 475?) or to use less memory in System 7.5.5 and below (why one would do that, I don't know), but when you do that, there is no overclocking. On my 575, that means the clock speed drops to the stock speed of 33MHz. Fully usable and no problems. Just no overclock. Then you switch 32-bit addressing back on, and then the overclock starts working again.

With Spicy, you get the overclock even in 24-bit addressing mode.

 

[phipli]

@JDW , does that mean the software overclock requires 32 bit addressing stays on then?

I mean, it just doesn't run if you have 24bit mode set, there are only so many hours in the day and I'd already spent over a week writing the extension and control panel. 24bit mode completely moves all the memory locations around that are being written to, there is a way to briefly switch to 32bit mode, but it takes time to learn how to do things and I had other stuff to get on with, so I just made sure it dealt with it elegantly (i.e. didn't crash) and left it at that.

There isn't a practical reason why you couldn't overclock in 24bit mode, its just... all software post 1990 works in 32bit mode, what are you running that needs 24bit and an overclock at the same time? The Apple II card certainly doesn't need a 40MHz host and surely you're already restarting in 32bit mode to get more than 8MB of RAM?

Basically I didn't think the edge case justified spending the time on it, because, well, I value my time above £0/hr.