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Macintosh SE EEPROM to ROM adapter


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So, you have a Mac SE, or you're building up a Mac SE reloaded board using damaged donor that might have bad ROM chips (corroded legs, dead chip etc). 

 

Well through the magic of the internet I can bring you this, an adapter that replaces the stock Toshiba TC531000 mask ROMs with any 27C010's you choose, so you can customise the image if you want! 

 

Test runs are printed in red, but available to anyone who wants one for cost of postage. 

 

Production boards will be open source but I may sell a batch for those that don't want the hassle of making PCBs! 

 

 

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IIRC you're also doing a re-engineering of the SE right? Would like to donate for this and that since it's amazing work for long time vintage mac supports. I scanned the PCB Reverse Engineering thread a few times I don't remember seeing a paypal link, so this is why I brought up donation/supporting :).

 

Would love a pcb. Would make a perfect gift for a friend who resurrects and refurbishes dead macs :)

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  • 2 weeks later...

I don't mean to be dense, I'm honestly curious, but first, here's where I'm coming from - 2 years ago, I noticed my best Mac Plus (platinum, 4 mb RAM) was no longer booting, so I recapped it and realized that the ROM was faulty, as I had another Mac Plus in working order, so a swap of the ROMs worked. I eventually equipped myself with the  TL866 II plus everyone has, and not knowing all too much about EEPROM writing, I stumbled upon a batch of Winbond W27C512-45Z and tried it out after figuring the hi-lo split. It worked. 

 

What is the exact advantage of the PCB you're doing here? The pinouts aren't the same? Meaning, I was extra lucky my EEPROM chips would work right away on the Plus?

 

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@Mu0n So the EEPROM's aren't the same pinout as the Mask ROM's the SE comes with - one address pin is in a different position. The 128k x 8 EEPROM's are 32-pin, but the Mask ROM's are 28-pin. 

@rickyzhang Well, thats the beauty of using EEPROM's instead - as long as the image fits in 128KB in 64KB chunks (Low/High) - then i see no reason you can't do that. 

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On 1/1/2021 at 3:29 PM, Mu0n said:

What is the exact advantage of the PCB you're doing here? The pinouts aren't the same? Meaning, I was extra lucky my EEPROM chips would work right away on the Plus?

 

 

At the change from 512Kbits (64KB) and lower to 1 Mbit (128KB) and larger, several pins in the DIP package pinout moved.   So it is not simple to substitute the larger capacity 1 Mbit chips for the 512Kbit chips, without using an adapter board such as this one.

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