"Spicy O'clock" project has started

[Kay K.M.Mods]

Hello new user here! I've been lurking on this forum for a few weeks now, after recently resurrecting a couple of vintage Macs that I used 20 or so years ago. After seeing the YouTube video by JDW on Spicy O'clock, I impulsively ordered one, without completely understanding all of the mods that would be required on my LC475, specifically the IC swap. I do see that there are MC88196DW80 available on eBay, but whether or not I could swap it out successfully is questionable at best. A question I have is, would leaving the MC88920 installed cause any damage or just make for a completely unsuccessful mod? As I watched JDW's video several times, I had already decided that ~42mhz would be my target and 40mhz would be better than the 33mhz I'm currently at, courtesy of a clip on gizmo purchased back in the day. This also as I do sometimes use a serial port joystick. I would assume that whatever course I may take, I would need to remove the clip on device...Correct?

Thanks!

Hi @yock1960 !

First, I need to explain why the LC475 PLL clock driver should be replaced from MC88920 to MC88916DW.

Concept

MC88920:
This is originally for 12.5MHz input and 25MHz output. The upper limit of this clock driver is 19.5Mhz input and 39Mhz output. Also, depending on individual differences, it may reach up to 40MHz, but it is difficult for the clock to drop or stabilize over time.

MC88916DW80:
The PLL clock driver installed in the Quadra 840AV has the performance of 25Mhz input and 50Mhz output.

So, if it's 39Mhz or less, you don't have to replace it. Of course, the performance of Spicy O’Clock is up to 51Mhz, so it's a little wasteful.

This is my blog links:

LC475 restore and Overclocking

『Mac LC475 restore, PSU build and Overclocking』

*Jun 21, 2021 Added few schematics and descriptions. I recently repaired my fri…

ameblo.jp

SpicyO'Clock! wiring diagrams for LC475

Spicy O'Clock wiring diagramsの画像

ameblo.jp

MC88916DW80, UTsouce store

MC88916DW80 Price - MC88916DW80 in stock - Buy MC88916DW80 on Utsource.net

Description: The MC88916DW80 is a single-chip, low-power, full-duplex, voice-band modem from Motorola. Features: Low power consumption Full-duplex operation Voi

www.utsource.net

Good luck!

 

[yock1960]

Hi @yock1960 !

First, I need to explain why the LC475 PLL clock driver should be replaced from MC88920 to MC88916DW.

Concept

MC88920:
This is originally for 12.5MHz input and 25MHz output. The upper limit of this clock driver is 19.5Mhz input and 39Mhz output. Also, depending on individual differences, it may reach up to 40MHz, but it is difficult for the clock to drop or stabilize over time.

MC88916DW80:
The PLL clock driver installed in the Quadra 840AV has the performance of 25Mhz input and 50Mhz output.

So, if it's 39Mhz or less, you don't have to replace it. Of course, the performance of Spicy O’Clock is up to 51Mhz, so it's a little wasteful.

This is my blog links:

LC475 restore and Overclocking

『Mac LC475 restore, PSU build and Overclocking』

*Jun 21, 2021 Added few schematics and descriptions. I recently repaired my fri…

ameblo.jp

SpicyO'Clock! wiring diagrams for LC475

Spicy O'Clock wiring diagramsの画像

ameblo.jp

MC88916DW80, UTsouce store

MC88916DW80 Price - MC88916DW80 in stock - Buy MC88916DW80 on Utsource.net

Description: The MC88916DW80 is a single-chip, low-power, full-duplex, voice-band modem from Motorola. Features: Low power consumption Full-duplex operation Voi

www.utsource.net

Good luck!

Really appreciate the response! Yes, I understand the limitations, but also my limitations! So for the time being I will leave the original IC in place, while I try to hone my SMD desoldering/soldering skills, which are in their infancy!

Love the power supply mod, BTW!

 

[Kay K.M.Mods]

Really appreciate the response! Yes, I understand the limitations, but also my limitations! So for the time being I will leave the original IC in place, while I try to hone my SMD desoldering/soldering skills, which are in their infancy!

Love the power supply mod, BTW!

If you already have SpicyO'clock!, I recommend doing only Step 2 of my blog. Keep in mind that the limit in this case is 40Mhz or less. When Spicy is shipped, the frequency is set around 40.7Mhz, so don't forget to set it lower than that.

See this for how to set the Spicy frequency:

https://9b917908-9bcc-4794-acf9-af00c9274443.usrfiles.com/ugd/9b9179_bec5a04f7eb34104b9f68e184c7386a8.pdf

Stephen Arsenault's resistance setting application for SpicyO'Clock!:

Spicy O'Clock Calculator

 

[yock1960]

If you already have SpicyO'clock!, I recommend doing only Step 2 of my blog. Keep in mind that the limit in this case is 40Mhz or less. When Spicy is shipped, the frequency is set around 40.7Mhz, so don't forget to set it lower than that.

See this for how to set the Spicy frequency:

https://9b917908-9bcc-4794-acf9-af00c9274443.usrfiles.com/ugd/9b9179_bec5a04f7eb34104b9f68e184c7386a8.pdf

Stephen Arsenault's resistance setting application for SpicyO'Clock!:

Spicy O'Clock Calculator

It will be interesting to see my results and if nothing else, another data point for your project! I'm also hopeful that if and when I swap the MC88920 out, that my 80ns VRAM is of the more resilient type!

Hmm, can't seem to attach a photo, but they are Mitsubishi M5M482257J.

 

[Zane Kaminski]

It will be interesting to see my results and if nothing else, another data point for your project! I'm also hopeful that if and when I swap the MC88920 out, that my 80ns VRAM is of the more resilient type!

Hmm, can't seem to attach a photo, but they are Mitsubishi M5M482257J.

On the subject of VRAM, does anyone know if the LC 575 and similar can be used with EDO VRAM? It’s not officially supported or discussed since EDO VRAM was a later development than the 575. Were it possible to use EDO VRAM, I could make a 50ns 512 kB VRAM SIMM using a single VRAM chip. If we could make sure that EDO VRAM won’t damage the machine, that would be great and then I could proceed on such a project.

 

[Kay K.M.Mods]

It will be interesting to see my results and if nothing else, another data point for your project! I'm also hopeful that if and when I swap the MC88920 out, that my 80ns VRAM is of the more resilient type!

Hmm, can't seem to attach a photo, but they are Mitsubishi M5M482257J.

Good news. Satanic MacClub will soon release a new high speed VRAM. It's 60Ns!
We also sell it!

 

[yock1960]

Good news. Satanic MacClub will soon release a new high speed VRAM. It's 60Ns!
We also sell it!

Yes, there seem to be a number of options for 60ns VRAM, but, my first practice attempt at removing a same size/type IC as the MC88920 was unsuccessful ! Got the chip off in one piece, but tore off two pads, using the leg lift method. There are two more similar chips on the old PC mainboard I sacrificed and I'm mulling my options. I'm resisting the purchase of a hot air rework station for a single use...but may end up doing it anyway.

 

[Kay K.M.Mods]

Yes, there seem to be a number of options for 60ns VRAM, but, my first practice attempt at removing a same size/type IC as the MC88920 was unsuccessful ! Got the chip off in one piece, but tore off two pads, using the leg lift method. There are two more similar chips on the old PC mainboard I sacrificed and I'm mulling my options. I'm resisting the purchase of a hot air rework station for a single use...but may end up doing it anyway.

OMG... really sorry I can't say anything to you. I'm sorry if you don't want to hear this, I don't think the Hot air station will be disposable. I can't think of anything else to remove the chips. It will also be useful when recapping. Practice a lot with the board you don't use anyway. Let's stop the repair suddenly. If you have a different board, I hope the next one works

 

[yock1960]

So, while I wait for Spicy O'clock to arrive (in Customs @ Chicago since the 25th! ), I've gone ahead and ordered a heat gun, which will almost certainly be here before Spicy. But! After discovering a new YouTube channel (CuriousMarc), I saw something that I wish I'd seen sooner, that seems like a better option to someone like myself. There exists a product, that is similar to solder, that melts at a lower temperature to apply, for chip removal. Saw it used to remove a 'gazillion' pinned large square IC off an old IBM PC. As with any method, I'm sure that one would need to practice...but it seems very attractive in this case, to avoid needing to protect all of the surrounding components from being affected by the heat gun.

Hmmm?

I fret about swapping chips...although, after watching so many videos, I'm much better prepared and feel that I could even deal with a...small disaster.

Well, nothing ventured, nothing gained! It's nearly certain that at some point I will want to push the LC475 to it's limit, but I will proceed in stages, partly out of caution, but partly to prolong that 'tinker high'!

 

[Kay K.M.Mods]

Customs clearance may take some time due to the effects of the war. I think it will take a long time, especially for devices that can be used as weapons, unfortunately. I gave this explanation to the shipping company several times this week. "This is a device for repairing vintage computers and is a replacement for crystal oscillators made with silicone oscillators."

And after trying various things, I think the hot air station is the best method right now. I also have hot tweezers, but it doesn't come into play. Before using the hot air station, use a low temperature solder to solder each pin little by little with a soldering iron, and then use the hot air station to melt the old solder well. It is recommended to cover the easily meltable connectors and sockets with aluminum tape.

The first attempt is a small trip with a series of high expectations and the risk of failure. It is important to enjoy everything.

 

[alxlab]

On the subject of VRAM, does anyone know if the LC 575 and similar can be used with EDO VRAM? It’s not officially supported or discussed since EDO VRAM was a later development than the 575. Were it possible to use EDO VRAM, I could make a 50ns 512 kB VRAM SIMM using a single VRAM chip. If we could make sure that EDO VRAM won’t damage the machine, that would be great and then I could proceed on such a project.

Actually I was wondering if we could just do the same trick with the 72-pin ram to make the EDO VRAM behave like FPM.

 

[Zane Kaminski]

Actually I was wondering if we could just do the same trick with the 72-pin ram to make the EDO VRAM behave like FPM.

It’s possible but I haven’t worked out the specifics. In VRAM the OE pin is called “OE/DT” meaning that it has an additional function multiplexed onto the same wire. So you have to apply a slightly more complex circuit gating the OE signal. Lemme try and work it out and I’ll post in a different thread

 

[JDW]

@Zane Kaminski
I was just talking to @Kay K.M.Mods yesterday about the $25 50ns VRAM from Silicon Insider. It's for PPC Macs and therefore not pin-compatible with the LC575 motherboard, but when my eyes spotted that my brain was laser-focused on the "50ns" part! The chip capacity is larger than the 575 MB can use, but I was wondering if any access RAM wouldn't just be ignored? Meaning, couldn't you just use those same chips or similar 50ns chips that are twice as large in capacity as what the LC575 can accept and then the 575 would just ignore the capacity it cannot use?

Two more things to consider...

1. As my soon-to-be-complete Spicy Part II video will show, my tests of Kay's (and Drake's) new low-latency 60ns VRAM demonstrate that it's possible to overclock an additional 1MHz. With the @Mr. Fahrenheit and @Drake 4-chip 60ns VRAM based on @Stephen 's PCB design, I can overclock to 49.2MHz and it is stable, with no pixel dust following the arrow pointer, and no Bus errors. With the newer "SMC" 2-chip 60ns VRAM that Kay sent to me (which also includes nifty blue LEDs on it too), I can get 50.2MHz sustained, largely without Bus errors. (Keep in mind that these speeds rank among the fastest ever recorded for an 040 Mystic.) I have also tested it for many hours at 50.5MHz with no pixel dust at all, it's just that I get an unexplained Bus error now and then, mostly when quitting Doom II. Indeed, I ran the Doom II demo for 12 hours straight during one test, and nothing bad happened at all, but when I quite the game -- Boom! Bus Error. I simply don't understand that, but I cannot see a correlation to VRAM. Must be a >50MHz issue. At 51.7MHz with the SMC VRAM, I get pixel dust after the arrow pointer.

2. The VRAM holy grail is 50ns (or faster). Why? Well, because I'm a Star Trek fan. You see, I want to boldly go where no MAN (politically incorrect, but hey, I'm 51) has gone before. I want to crank Spicy to it's max setting of 51.7MHz and see no pixel dust follow the arrow pointer. I want to see Kay release a future Spicy O'Clock that breaks past 52MHz and let's us test at 55MHz! But to do all those glorious things, we need faster-than-60ns VRAM. So if EDO will do the trick, I say it's time to explore that possibility.

As you will also see in my new video, I am using a nice 45mm heatsink that covers the entire top of the 68040. It's neat because so most heatsinks are 40mm (too small) or 50mm (too large). I then used Kay Koba's trick of using two machine screws to mount a 40x40x10mm fan direction on top, with air firing straight down, to add further cooling. Thermal tape keeps the heatsink locked down to the CPU. Tape is better than thermal epoxy because tape can be removed without damaging anything. But thermal tape isn't as good as quality paste like Thermal Grizzly Kryonaut. So MY DREAM is to have a heatsink solution that CLIPS IN PLACE, such that I can use PASTE, not TAPE, AND have the ability to add a fan on TOP, all within the HEIGHT LIMIT of the Color Classic. I guesstimate that to be about 28mm or so above the 040 CPU.

 

[Zane Kaminski]

Regarding the PPC VRAM, when you say Silicon Insider do you mean PurpleRAM? The PurpleRAM boards look good but I am a bit put off by the presence of 3.3V chips on his listing photo. My Power Mac 7200 has 5V chips and I don’t think 3V is right. I guess it works—maybe it’s even faster when running at 5V—or maybe it’ll break after a while.

Other than the 3V voltage (and there are 5V versions of the same chip), one issue is with how the VRAM is pinned out for use on the PPC machines. The PurpleRAM 112-pin DIMM has a KM4216V256 VRAM chip (or KM4216C256 for the 5V version). It’s 256k x 16 bits so a single one is all that’s required for a 68-pin VRAM SIMM except for one problem. The chip has two “WE” pins to control whether data is written to the low/high bytes. We want “dual CAS” instead of “dual WE.” The dual CAS version is the KM4216C258. That’ll work perfectly (with the EDO-to-FPM circuit) but can we source any inexpensively from a place that isn’t known for remanufacturing ICs? I avoid remanufactured ICs at all costs—it’s not professional in my opinion unless absolutely necessary. And if a gizmo must use remanufactured chips, I always design to the lowest available speed grade. So I wouldn’t feel comfortable selling “50ns” VRAM with remanufactured markings on the chips. I’d have to develop a timing test to qualify the SIMMs. They’re also specced at 70 degC so ideally the tester should incorporate a heat chamber. Too complicated for me and Garrett’s Workshop. I found some genuine VRAMs of the correct type the other day when I posted but now they have been sold. So I would need to find some more original chips before thinking more about pursuing the project.

 

[JDW]

Regarding the PPC VRAM, when you say Silicon Insider do you mean PurpleRAM?

Was I mistaken in assuming that the guy in France (Silicon Insider) is the creator of that VRAM on EBAY? I thought those VRAM SIMMs where his creation.

 

[Zane Kaminski]

Was I mistaken in assuming that the guy in France (Silicon Insider) is the creator of that VRAM on EBAY? I thought those VRAM SIMMs where his creation.

Yeah I think it’s the same person. I’m probably confused due to being up all last night.

 

[yock1960]

That wasn't too bad for a first try (with a heat gun). Actually, I did the chip that I did the leg lift method, which I had re-soldered on first....but that doesn't count, as it was rework of rework! I still have one more similarly sized chip to remove, then I will do more practice resoldering. What is an 'ideal' temperature to use? I used 360C first...took a while, but I think that was due to too much solder on my resoldering. Second attempt I bumped the temp up to 370C, was quicker. I ordered (2) MC88916DW80 chips, they should be here in 8-10 days. Maybe Spicy will be here by then!

Having appropriate tools and being able to watch this done on YouTube is HUGE!

 

[JDW]

MC88920:
This is originally for 12.5MHz input and 25MHz output. The upper limit of this clock driver is 19.5Mhz input and 39Mhz output. Also, depending on individual differences, it may reach up to 40MHz, but it is difficult for the clock to drop or stabilize over time.

MC88916DW80:
The PLL clock driver installed in the Quadra 840AV has the performance of 25Mhz input and 50Mhz output.

So, if it's 39Mhz or less, you don't have to replace it. Of course, the performance of Spicy O’Clock is up to 51Mhz, so it's a little wasteful.

Because the MC88916DW80 was mentioned by Kay, I should remind everyone that on my LC575 board, I have the slower MC88916DW55 chip. You can see that chip in this section of my Part I video. But despite that slower DW55 chip, I have broken the 50MHz barrier with Kay's new 2-chip VRAM. There's something so awesome about that, I really can't explain it in words. I am extremely grateful to the brilliant people who made this possible. It's incredible.

Next...

Only very rarely do I get Bus errors at 50.1MHz (in System 7.1), but I get them frequently at 50.5MHz and higher. What I do NOT know is if the Bus errors at 50.5MHz and higher are related to my having the slower DW55 chip. We need a larger pool of Mystic owners overclocking beyond 50MHz to know for sure, since I don't have time to swap my DW55 for a faster DW80 and test right now.

Lastly...

My Spicy Part II video is now in final editing and hopefully can be uploaded this weekend. Even after a lot of editing, it has still turned out to be 1 hour 10 minutes long. That's why I'm deciding if I want to cut out some of my game testing (which nicely demonstrates performance at a given clock speed) or just leave it all in (with my commentary, of course). Some people hate long videos, but I really do try to stay on point and provide useful information throughout the video. I don't talk about off-topic things like what I had for breakfast.

I will give Kay and Paypal supporters a preview of my new Spicy Part II video before it goes public, hopefully this weekend. If someone finds a problem, then I may need to edit and export again for a lovely 6.5 hours, and then re-upload. That "bug fix" process often delays the official release of my videos. I need a faster modern Mac! Don't we all? But when it comes to a faster Color Classic Mystic, Spicy O'Clock and that new low latency VRAM certainly delivers!

 

[yock1960]

Because the MC88916DW80 was mentioned by Kay, I should remind everyone that on my LC575 board, I have the slower MC88916DW55 chip. You can see that chip in this section of my Part I video. But despite that slower DW55 chip, I have broken the 50MHz barrier with Kay's new 2-chip VRAM. There's something so awesome about that, I really can't explain it in words. I am extremely grateful to the brilliant people who made this possible. It's incredible.

Next...

Only very rarely do I get Bus errors at 50.1MHz (in System 7.1), but I get them frequently at 50.5MHz and higher. What I do NOT know is if the Bus errors at 50.5MHz and higher are related to my having the slower DW55 chip. We need a larger pool of Mystic owners overclocking beyond 50MHz to know for sure, since I don't have time to swap my DW55 for a faster DW80 and test right now.

Lastly...

My Spicy Part II video is now in final editing and hopefully can be uploaded this weekend. Even after a lot of editing, it has still turned out to be 1 hour 10 minutes long. That's why I'm deciding if I want to cut out some of my game testing (which nicely demonstrates performance at a given clock speed) or just leave it all in (with my commentary, of course). Some people hate long videos, but I really do try to stay on point and provide useful information throughout the video. I don't talk about off-topic things like what I had for breakfast.

I will give Kay and Paypal supporters a preview of my new Spicy Part II video before it goes public, hopefully this weekend. If someone finds a problem, then I may need to edit and export again for a lovely 6.5 hours, and then re-upload. That "bug fix" process often delays the official release of my videos. I need a faster modern Mac! Don't we all? But when it comes to a faster Color Classic Mystic, Spicy O'Clock and that new low latency VRAM certainly delivers!

I don't know...personally, I would find what a 'transplanted' American living in Japan, eats for breakfast interesting , but that's me.

I would also vote to keep content versus removing...there is the FF button, especially if you use 'chapters'.

As far as Bus errors go, with my admittedly limited knowledge, that seems to me to point to a memory access issue, perhaps similar to the VRAM issue already understood. Even at 50.5mhz, if I understand correctly , you seem to still be within the capabilities of the MC916DW55.

Since I'm still waiting on my Spicy to arrive, also on MC88196DW80, I have been monitoring the thermal characteristics of my MC88920 @ 33mhz, just so I can...perhaps...see something interesting as I tinker...

I do know that keeping the case on, makes a big difference in temperature, for the CPU at least, as airflow is nil with it off. I haven't tried a fan on the heatsink yet, A) clearance, B) I only use thermal paste and wonder about 'migration' over time. I could switch to tape...but that's less conductive and my inquisitiveness falls short of undertaking a study.

 

[nottomhanks]

I was thinking about the fan thing this morning: what about this? https://www.amazon.ca/bluederst-Alu...keywords=40mm+heatsink&qid=1648821583&sr=8-32