Quote:
Originally Posted by paulsherwin
Good stuff Kat, well done.
I have to say it seems a pretty cretinous design decision to use a non-replaceable battery in any piece of equipment, let alone in an (at the time) expensive server. Why didn't Mostek just use a coin cell holder on the part, and given that they didn't why didn't Sun use something else?
|
Umm..
Some PCs used a similar part (the CMOS + RTC) and originally used NiCd battery on motherboard. Which would leak and corrode board.
Some used 2 x AA (Amstrad)
Some used large Lithium cells (4 main kinds)
Some used something very like (Identical?) that in the Sun.
I have 3 modules from PCs like the Sun module here
ODIN OEC12C887 x2
Dallas DS1287 (underneath is full 28pin chip)
Dallas DS1220Y (Same size but under you can see maybe 8pin DIL) (may not have a clock!)
Later they switched to coin cell in holder as per current PCs.
I have 2 x bare MC146818, one Hitachi and one Motorola
I have 2 x Mostek chips but they may be 2Kx8 SRAM
(all from PC)
All RTCC with extra "unused" registers used for original "CMOS" settings. Often the "CMOS" settings now is extended to a Flash memory chip too. A few boards didn't use "cmos" and only Flash and a power cut during setting change could "brick" the MoBo as unplugging the coin cell would only reset the clock
I think the idea of "all in one" crystal, battery, chip solution was to make it easier for mobo designers. I designed a Z80 controller in 1979 with a RTC and battery backup. Unfortunately it got the register values "clobbered" on power off or power up. I didn't need the clock really so left those parts out rather than fix it.
The original IBM PC in 1980/1981 unlike ACT Sirius1 contemporary had no HW RTC at all or "CMOS" BIOS settings. The advent of a variety of different hard drives led to the HW RTC becoming standard to have somewhere to store the drive geometry.