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This is a great project. I recently purchased a Mac 512k and was surprised to find a MacSnap RAM expansion card installed. I found your SCSI recreation board and ordered some PCB's. I was planning on using a BlueSCSI v2, but was concerned about power. I have several old external 20mb SCSI...

I did try the ST M27C512 with the Plus flashed into them, but had a similar result. I'm going to have to wait until the WinBond W27C512 ROM chips arrive. Turns out the ST M27C512 ROM chips have data on them and I don't have a strong enough UV light to erase them. I just read the chips and...

I did not expect success with my first try. First image is with stock Mac 512k 64mb ROM - No chime and steady screen distortion. Second image is with ST M27C512 ROM's with Mac 512k flash. - No chime. Distorted Growl, then screen would flash, then go blank. This would repeat. Any...

All wired up. EDO RAM in place. Switches are set. I'm going to attempt to boot later today. ROM I think will be my issue with booting. I currently have stock ROM installed. I have some ST M27C512 ROM's programed for the 512k. I also have a BMOW ROM-inator that I am setting up later today. I...

Soldering the pins on the inside of the DIP sockets was tricky. I used a very long soldering tip. These generally don't produce a lot of heat at the tip. I did slightly melt the plastic on the socket as I tried to reach the middle pins, but not enough to ruin it. I have continuity between the IC...

I forgot to order the 6 pin connector plug wires. They arrive today. I also purchased some 6 pin right angle sockets. I didn't need them, but thought others could use the link. I should in theory be able to boot tomorrow. However, I am not sure on the IC's I flashed the ROM file. I have also...

I flashed some 28 pin ST M27C512 with the ROM's provided in the link to make them 512k and Plus ROM's. I'm going to try these ROM's first and attempt a boot. I also flashed the 32 pin SST 39SF040 for the BOMW ROM-inator I am putting together. I have some new PCB's arriving soon to make the...

This is how I lined up the expansion card to the motherboard by attaching the DIP socket to the card and placing it onto the motherboard. Then soldering the pins. So much easier this way to line up the card to the board.

Thanks for the advice. I removed the round pin DIP sockets and replaced them with the blade type. The best way I found to properly locate the expansion card to the DIP sockets on the board was to attach the DIP sockets onto the expansion board pins then attaching the expansion board to the...

I was wondering a bit how this was done. I soldered DIP Sockets (round type) to the top of the IC's (UF4, U11F and U11G). I had tried the lighter pin version, but found that the pins from the board were a bit stiff and would not fit properly. It's not pretty, but works. There wasn't much flex...

The SST39SF040-70-4C-PHE are 32 pin which will only work with the ROM-inator PCB, but the ST M27c512 is 28 pin and is 512kb that matches the current ROM socket. Or I can pick up what ever you recommend that works with the RAM expansion card.

I have the original ROM from my other 512k board that now has a ROM-inator. Probably similar to the other board. it has similar Hi - 342-0220-A Lo - 342-0221-A I also am putting together a BOMW ROM-inator board that I had made recently from JLCPCB and have several of the recommended ROM's for...

Test fit. Very nice fitment! I just need to place headers on the board and then run jumper wires.

I have all the components installed on the board. I just need to start adding the headers. I should be able to mount the PCB to the motherboard early next week.

Thankfully I have two Mac 512k boards. I was planning on installing the RAM expansion card on the one without the ROM-inator as a test.

I was just looking at the BOMW ROM-inator install instructions and it uses the same two pins as the RAM expansion card (pins 45 and 46. So this would mean two wires connected with those pins. Just trying to make sure I get this correct. Thanks again for the new information.

This is really helpful information. Thank you. I will be starting to build my board this week.

All my parts are in. I am preparing to build two expansion cards. I did create a photo parts location with pin locations. (please correct me if this is wrong). I have all the proper headers, but am wondering about stacking and proper header height so the board can clear the case. Are headers...

Very cool. Thanks for the info. I purchased the correct headers for J11 and J12. I must have bought the last ones. Same Amazon vendor had listing on eBay as well. Both are out of stock. https://www.ebay.com/itm/134627074915 I ordered enough components from Mouser to make two. The RAM chips...

My PCB's arrived this morning - quicker than I thought.