bryce@COGSCI.BERKELEY.EDU (Bryce Nesbitt) (05/29/87)
> [I'm looking] for a good time of year chip Here's my biases: OKI - MSM5832 series. Good, cheap, but slow. Unless you are using anceint technolgy use only for a parallel-port type application. Requires some hassle for backup switching/latchup protection. SARONIX makes a version with built-in crystal. OKI - MSM6242 series. Unlike grr I dislike these. This is a bias caused mostly by the fact that I did not have +12 on tap and the costs of the backup circuit added to the cost of the chip where too much. No special advantages and not especially cheap. Recent rumor says that this chip is suceptible to noise and hard to get oscilating. 1 second resolution. OKI - (part number not on hand) Very nice SERIAL chip. OKI will be happy to do a new production run if your order ~10,000. All the clock data I can lay my mitts on is for microprocessor bus versions. If I already have two microprocessor setable I/O pins avaiable I would like a say, 8 pin chip that I talk to serially. Bonus for the person who finds a second source for the chip used in the Apple Macintosh; the original manufacturer went pins-up. RICOH - RP5C01/RP5C15. The 01 has 13 bytes of ram but requires much hassle on backup including pullup resistors on all pins. The 15 junks the ram but is less painfull on backup. Both need external powerdown detection. Same price range as the MSM6242. INTERSIL - ICM7170. Nice 100th/sec resoulution. On board power down. Fast. Check price. 24 pin package. MOTOROLA - MC146818 (no information) NATIONAL - MM58167 (no information) DALLAS - DS1215/6. Easy to use, fast, small 16 pin package. Power-down detection on chip. Support for two batteries. Cheap. Includes "free" CMOS ram backup support. Can be used without it's own address space by twiddling with a 64 bit "magic" number. Some have had problems with dirty power supply, so use caution. 100th second resolution. My overall number one pick. THOMSON/MOSTEK - MK48T02 The "Cream of the crop". It will cost a lot-> about $15, but for your money you get built in power-down detection, indeed a built in 17 year battery. Built in oscilator. Static ram interface, indeed you get 2K of battery-backed RAM. To your hardware it looks like a 2K RAM chip, in 120,150,200 or 250ns flavors. To your software the last 8 bytes contain the clock registers. 24 pin static ram pinout. A "tophat" contains the battery and oscilator. A clever repair person could replace the battery. 1 second resolution. On board software clock calibration. ------------- Ack! (NAK,EOT,SOH) |\ /| . {o O} . bryce@cogsci.berkeley.EDU -or- ucbvax!cogsci!bryce ( " ) U Single tasking? Just say *NO!*