Macintosh Rom-Inator Mishaps

[DemagnetizedMedia]

I recently designed a single sided version of the Rom-Inator, but after flashing the roms and putting the Rom-Inator in the system, it threw up a simasimac on the screen. Any ideas why? I already tried reflashing the roms but that didn't change anything.

 

[DemagnetizedMedia]

Here's a picture of the Rom-Inator View attachment IMG_20240424_212400957.jpg

 

[halkyardo]

Does it work if you put the original ROMs back in?

If so, then my guess would be either that you've got a shorted or missing trace somewhere on your ROM board, or your flash chips or the data that you're programming them with are bad. As a start, I'd recommend cross-checking every pin's connections against the schematic using a multimeter. If you're able to share the schematic that you used and images of the board layout, that would make it a lot easier to help you troubleshoot it.

 

[demik]

Doesn't it need a 74 series something chip as well to fix the chip select ?

 

[DemagnetizedMedia]

Yes, It uses a 74HCT02 for that, I just have it on the bottom out of view.

 

[DemagnetizedMedia]

I'm going to compare the hex data from the chip with the hex data from the original file to see if they're the same later

If they are the same then it's probably something wrong with the board.

 

[Nixontheknight]

I'm going to compare the hex data from the chip with the hex data from the original file to see if they're the same later

If they are the same then it's probably something wrong with the board.

Get back to us with the result, as this can also happen with bad RAM or when the voltage from the analog board is out of spec

 

[DemagnetizedMedia]

Aha! I figured out that the arduino rom writing program had a bug where it refused to write to hex address 0x0. I switched over to another arduino project https://bertiusgames.com/projects/eeprom.html, and this one seems to work (the hex data on the chip was identical to the data in the original file!) I haven't finished programming the chips but when I do I'll update you all on what the mac does.

 

[DemagnetizedMedia]

Frankenstein's monster is alive! The new rom flashing program worked like a charm, and my Mac is now fully up and running!View attachment IMG_20240425_214927338_HDR.jpgView attachment IMG_20240425_214514415_HDR.jpgView attachment IMG_20240425_213344753_HDR.jpg

I noticed that there is a slight hum from the speaker, but I think it's alright.