Again, this is an ancient thread, but bears some adding to.
The original GVP Jaws II A1230 used the iButton (Dallas, then Maxim, and now Analog) DS1494. This was replaced with a DS1994. The DS1994 was discontinued per -BobW-.
The 1494 and 1994 were >04h families of the iButton with clock functionality. They had the following identifier:
8-Bit CRC Code + 48-Bit Serial Number + 8-Bit Family Code (04h)
The >04h family essentially worked alike. That's why the 1994 was a drop in replacement for the 1494.
DS1994 data sheet:
https://www.analog.com/en/products/ds1994.html#product-overviewAnalog has come up with a "Hey, here's how you should replace a DS1994, because we don't make them anymore" article:
https://www.analog.com/en/design-notes/alternatives-to-the-ds1994l-4kb-plus-time-memory-ibuttonreg.htmlOn the above webpage, the DS1904 is the suggested replacement and has a nice footnote by it, stating: "Alternative device is a functional replacement, but requires some software adaptation." The above page also states "And another footnote on the data sheet for the DS1904 states that "The DS1994L has no drop-in compatible replacement device."
DS1904 Datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/ds1904.pdf8-Bit CRC Code + 48-Bit Serial Number + 8-Bit Family Code (24h) [note, it's not a >04h]
If you look a bit further on the above data sheet for the DS1904, you see that the time is reported as a "32 bit binary counter" where the 1494/1994 had it as a "40 bit binary counter." It uses the same date/time format as the DS1994 but with one second resolution. I don't know if that will break the GVP or not.
So there's some differences. Anyone do a DSxxxx Clock replacement recently? I'm assuming the GVP ROM uses the 1-wire protocol that reads the clock? If we needed to make any adjustments to read a slightly different format, I'm guessing we would need to desolder the ROM, make our own with some modifications, and then put a new ROM on board with some sort of repair type service.
