Many of you are already aware of Phil Greenland's Github project where he uses ATTiny85 to replace the RTC (Real Time Clock) on SE/30 motherboards. It's neat because it saves PRAM to onboard flash memory. If you don't care about the date/time (doesn't get saved to flash), then you can forgo installing a PRAM battery altogether. You can find them sold by CayMac Vintage and other places. I'm creating this thread because I was surprised today to find nobody out there showing photos of the proper installation orientation, no even the sellers of the little guy, so I am going to rectify that now with the following photos.
Pin-1 on the stock RTC is marked by a dot (as is true of any IC). The stock RTC chip's dot appears where the SQUARE PAD is shown in the above photos. There is no dot marking on those ATTinyRTC PCBs because I guess the creators think most people will differentiate between the lone SQUARE pad and the other round pads. True, but a dot would be even better. Nevertheless, you now have my photos above to guide you.
By the way, I spoke to Phil quite some time ago about current consumption. It draws a whopping 1mA, which is a lot more than the stock RTC. Even so, it's not an issue at all UNLESS you use a PRAM battery. Even if you use the GOOD PRAM batteries (stock type, which have long life) instead of the short life COIN CELL batteries, your battery will die in 2 weeks because of that 1mA power drain.
In other words, don't use a PRAM battery with the ATTinyRTC because you will be wasting your money. The only thing a PRAM battery would backup is the date/time, which I agree is nice. But unless the current consumption is reduced to stock RTC levels (by way of altering the design), there's no practical reason to use a PRAM battery.
SE/30 Reloaded Motherboard
Stock SE/30 Motherboard
Pin-1 on the stock RTC is marked by a dot (as is true of any IC). The stock RTC chip's dot appears where the SQUARE PAD is shown in the above photos. There is no dot marking on those ATTinyRTC PCBs because I guess the creators think most people will differentiate between the lone SQUARE pad and the other round pads. True, but a dot would be even better. Nevertheless, you now have my photos above to guide you.
By the way, I spoke to Phil quite some time ago about current consumption. It draws a whopping 1mA, which is a lot more than the stock RTC. Even so, it's not an issue at all UNLESS you use a PRAM battery. Even if you use the GOOD PRAM batteries (stock type, which have long life) instead of the short life COIN CELL batteries, your battery will die in 2 weeks because of that 1mA power drain.
In other words, don't use a PRAM battery with the ATTinyRTC because you will be wasting your money. The only thing a PRAM battery would backup is the date/time, which I agree is nice. But unless the current consumption is reduced to stock RTC levels (by way of altering the design), there's no practical reason to use a PRAM battery.