SMC Fat Mac Switcher

Kay K.M.Mods

Active Tinkerer
Sep 23, 2021
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www.kerosmm.com
Many of our products have simple and interesting ideas, but this one is even simpler and innovative...??? But look anyway!
Jun 12, 2023, New Instruction here:




This Fat Mac Switcher is an item that can switch Mac128K to 512K or Mac512K to 128K with a single switch. *For 512K, optional adapter board is required.


IMG_5807 2.jpegIMG_5811.jpeg

It features:

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-512K and 128K switching is possible. LED lights when 512KB is used

-Supports ROM-inator Resurrections
IMG_5390.jpeg
-Supports BMOW FloppyEMU

-Support SYSTEM 6.0.8 (at 512KB)
IMG_5398.jpeg
-HD20 support *FloppyEMU can also be used



Install on Mac128K

In this case, you need to replace all 16 memory with 41256 to 512KB. Assuming that's the case, attach the Fat Mac Switcher to the open pin header footprint at position E3 on the logic board. *The only thing that needs to be processed at this time is to cut one place on the router that connects pin 1 and pin 2. This is absolutely necessary to release the pulled-up DRAM pin 1.
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Install on Mac512K

Install it in a position near the keyboard jack. Remove all the parts circled in red in the fourth photo, AS253, C51, R42, R40, and R41. Absorb the right side of the W1 jumper pad.
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Solder the Mac512K adapter and the Fat Mac Switcher first. Attach a pin header to connect the logic board to the Mac512K adapter. 16 pin on the AS253 position and 1 pin on the right side of W1. Install the adapter.

BTW, French guy on Twitter gave me this link:


It looks like someone has tried Mac512K to 128KB in software in the past... But he doesn't seem to be doing well. I hope he finds this post!
 

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Last edited:

JDW

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Another absolutely fantastic gizmo from Kay Koba.

I've long thought it very funny so many people pay high prices for either a 128K Mac or 128K motherboard only because it was "the first Mac." Dog Cow's technical dive into differences notwithstanding, the Mac512, with 64K ROMs, is essentially the same as the 128K board, yet with a more usable amount of RAM. But because the Mac512 technically wasn't "the first," it doesn't get priced as high (on average).

That's a good thing for intelligent vintage Mac buyers, of course. Lower prices are always better, especially when you get more! But paying significantly higher prices for 1/4th the RAM makes zero sense to me, especially since the Mac512 came out only months after the 128K, in Sept. 1984. So to differentiate "the first" between those two models is rather silly, in my opinion. But if everyone today prefers to buy the 128K, making the 512K cheaper as a result, it's wonderful for the frugal buyer.

Kay's announcement today means anyone can now have the best of both words: the ability to buy a Mac512 for a lower price than a 128K AND the ability to boot with 128K RAM too! With the flip of a DIP switch, you can instantly RAM-hobble your Mac512 into the excessively priced version that everyone seems to want!

My first Mac was the 128K in early 1984. My father brought that "first Mac" home with an ImageWriter I printer. Sadly, the machine cost so much, he did not also buy the external 400K drive, which is a genuine lifesaver for the 128K model. I remember one time I had to swap two 400K floppies on the internal drive 100 times. I kid you not. The limited RAM of the 128K machine means more Disk Swapping Hell than you can imagine. And because I lived through that, using the 128K for real work back in the day, I have little desire to be stuck with 128K of RAM, which is all you get if you buy a 128K model.

Of course, Kay's device will work with the 128K Mac or the 512K Mac, but you would need to modify either motherboard to make it work. Many 128K owners very well may be purists who don't like to touch the stock board, regardless of the mod being removable. But technically, with Kay's device (and the required modifications), you have a switch that lets you choose to boot with 128K RAM or 512K RAM. That's awesome!

I myself have Kay's ROM-inator installed in one of my 512K machines, which means I'm not a purist. I love making it boot from the ROM -- doing something more than it was originally designed to do. And yet, if I don't boot from the ROM, it's the same old Mac512. The ROM-inator mod hasn't tarnished the Mac in any way. The same is true if you install the new Fat Mac Switcher. It's great the RAM switcher is fully compatible with the ROM-inator, and the FloppyEMU too.

Note that I've not installed the Fat Mac Switcher yet because it's brand new and only now becoming available, but I just wanted to express my love for the concept. It allows you to see how it feels to have that "first" Mac, with only 128K of RAM. And if there are programs that ONLY RUN on the 128K, you will get that benefit too. So while it may not be so fun to use with such limited RAM, it's amazing that Kay made it possible for us to achieve that at the flip of a switch!

I am constantly in awe of the insanely great devices that Kay Koba creates. Our hobby is vastly better as a result.
Thank you, Kay!
 

Crutch

Tinkerer
Jul 10, 2022
292
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This is a cool device because I love hackery. But for practical purposes — what programs only run on the 128K Mac? I’m sure there are some, though I can’t think of any.
 
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Kay K.M.Mods

Active Tinkerer
Sep 23, 2021
285
628
93
Tokyo
www.kerosmm.com
Another absolutely fantastic gizmo from Kay Koba.

I've long thought it very funny so many people pay high prices for either a 128K Mac or 128K motherboard only because it was "the first Mac." Dog Cow's technical dive into differences notwithstanding, the Mac512, with 64K ROMs, is essentially the same as the 128K board, yet with a more usable amount of RAM. But because the Mac512 technically wasn't "the first," it doesn't get priced as high (on average).

That's a good thing for intelligent vintage Mac buyers, of course. Lower prices are always better, especially when you get more! But paying significantly higher prices for 1/4th the RAM makes zero sense to me, especially since the Mac512 came out only months after the 128K, in Sept. 1984. So to differentiate "the first" between those two models is rather silly, in my opinion. But if everyone today prefers to buy the 128K, making the 512K cheaper as a result, it's wonderful for the frugal buyer.

Kay's announcement today means anyone can now have the best of both words: the ability to buy a Mac512 for a lower price than a 128K AND the ability to boot with 128K RAM too! With the flip of a DIP switch, you can instantly RAM-hobble your Mac512 into the excessively priced version that everyone seems to want!

My first Mac was the 128K in early 1984. My father brought that "first Mac" home with an ImageWriter I printer. Sadly, the machine cost so much, he did not also buy the external 400K drive, which is a genuine lifesaver for the 128K model. I remember one time I had to swap two 400K floppies on the internal drive 100 times. I kid you not. The limited RAM of the 128K machine means more Disk Swapping Hell than you can imagine. And because I lived through that, using the 128K for real work back in the day, I have little desire to be stuck with 128K of RAM, which is all you get if you buy a 128K model.

Of course, Kay's device will work with the 128K Mac or the 512K Mac, but you would need to modify either motherboard to make it work. Many 128K owners very well may be purists who don't like to touch the stock board, regardless of the mod being removable. But technically, with Kay's device (and the required modifications), you have a switch that lets you choose to boot with 128K RAM or 512K RAM. That's awesome!

I myself have Kay's ROM-inator installed in one of my 512K machines, which means I'm not a purist. I love making it boot from the ROM -- doing something more than it was originally designed to do. And yet, if I don't boot from the ROM, it's the same old Mac512. The ROM-inator mod hasn't tarnished the Mac in any way. The same is true if you install the new Fat Mac Switcher. It's great the RAM switcher is fully compatible with the ROM-inator, and the FloppyEMU too.

Note that I've not installed the Fat Mac Switcher yet because it's brand new and only now becoming available, but I just wanted to express my love for the concept. It allows you to see how it feels to have that "first" Mac, with only 128K of RAM. And if there are programs that ONLY RUN on the 128K, you will get that benefit too. So while it may not be so fun to use with such limited RAM, it's amazing that Kay made it possible for us to achieve that at the flip of a switch!

I am constantly in awe of the insanely great devices that Kay Koba creates. Our hobby is vastly better as a result.
Thank you, Kay!
Thank you James! I was worried because your reply was long, but I was relieved that it was all praise:ROFLMAO:
It's actually a device I built just for my own curiosity. But it worked so well that I can safely recommend it to everyone.
 
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Kay K.M.Mods

Active Tinkerer
Sep 23, 2021
285
628
93
Tokyo
www.kerosmm.com
This is a cool device because I love hackery. But for practical purposes — what programs only run on the 128K Mac? I’m sure there are some, though I can’t think of any.
Here's a little info, but I don't know if this is correct,
I'm not very familiar with this generation of Mac software, so I think it's a discovery for users!
 
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retr01

Senior Tinkerer
Jun 6, 2022
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Now, I am tempted to buy a Mac 512k and a Mac Plus after that... :)

@JDW is a great salesman and marketing guru for all vintage compact Apple Macintosh! The stories are fantastic to hear about the magic of the Macs back in the day and today with @Kay K.M.Mods' insanely great mods.
 
Last edited:

Patrick

Tinkerer
Oct 26, 2021
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i get it. the first of whatever is more collectable. not because its useful. most 128k's i'm sure is just wall candy.

>especially since the Mac512 came out only months after the 128K, in Sept.
to add on to this. the first Mac we even saw, the one that was happy to get out of that bag, was a 512k. The 128k doesn't have enough memory to talk!

FWIW, i was able to find a Mac 128k cheap locally. It had sad mac. Lucky it was just some bad ram. (also the sound doesn't work that i still haven't figured out.)

This product is really cool and I love how Kay can just come up with random stuff like this, make it, and sale it .. just 'cause.