UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Mostek/ST 'Timekeeper' IC (Sun NVRAM) repair

Kat Manton · 28th Jun 2011, 5:32 pm

Hi,

The PC devices aren't all that similar; there's much less SRAM for a start (about 50 bytes IIRC) and as Paul notes, an embedded battery/cell is unusual (I've never seen one in any PC and I've been inside a lot!)

The Suns have 2048 bytes (M48T02) or 8192 bytes (M48T08); the identity of the system (serial number, host ID and MAC address) is stored in it by Sun when the machine is manufactured. There's a lot of configuration information stored, much of it as strings of text. It's also possible to store commands and small Forth programs in it, to be executed before booting the OS (the boot PROM contains a Forth interpreter, debugger and disassembler; the manual for it runs to 182 pages!)

Among other things, any licensed software installed would be keyed to the host ID; if the NVRAM dies, the host ID disappears; even if you manage to manually boot the OS, licensed software won't run.

I suspect that a machine coming up on a network with MAC address of FF:FF:FF:FF:FF:FF (the broadcast address) might cause a few problems, too...

Sun could provide a pre-programmed NVRAM containing the system's identity if given the code which appears on a label on top of them in most machines. I don't think it's cheap and may not be possible with any 'end-of-lifed' system and/or without a current service contract.

If you replace or repair the device yourself, you need to have this information written down somewhere; it's possible to load it from the OpenBoot prompt. Otherwise the only recourse is to make it up (which I'll have to do with a few machines.)

So if you happen to have some old Sun kit which hasn't yet suffered amnesia, write down all the information before it disappears! (I'm doing that with the few machines which still retain it; I'll put it on a label underneath or inside.)

Fortunately in the 1000E, the system's identity is stored in EEPROM on the control board and is copied into the NVRAM on each system board. I've noted it all anyway, just in case.

Failure of the CMOS battery in a PC is somewhat trivial in comparison; it might get mildly tricky with very old machines which have the CMOS configuration utility on floppy. Not something I'd bother writing about...

Kat

28th Jun 2011, 5:32 pm	#7
Kat Manton Retired Dormant Member Join Date: Jul 2005 Location: West Yorkshire, UK. Posts: 1,700	Re: Mostek/ST 'Timekeeper' IC (Sun NVRAM) repair Hi, The PC devices aren't all that similar; there's much less SRAM for a start (about 50 bytes IIRC) and as Paul notes, an embedded battery/cell is unusual (I've never seen one in any PC and I've been inside a lot!) The Suns have 2048 bytes (M48T02) or 8192 bytes (M48T08); the identity of the system (serial number, host ID and MAC address) is stored in it by Sun when the machine is manufactured. There's a lot of configuration information stored, much of it as strings of text. It's also possible to store commands and small Forth programs in it, to be executed before booting the OS (the boot PROM contains a Forth interpreter, debugger and disassembler; the manual for it runs to 182 pages!) Among other things, any licensed software installed would be keyed to the host ID; if the NVRAM dies, the host ID disappears; even if you manage to manually boot the OS, licensed software won't run. I suspect that a machine coming up on a network with MAC address of FF:FF:FF:FF:FF:FF (the broadcast address) might cause a few problems, too... Sun could provide a pre-programmed NVRAM containing the system's identity if given the code which appears on a label on top of them in most machines. I don't think it's cheap and may not be possible with any 'end-of-lifed' system and/or without a current service contract. If you replace or repair the device yourself, you need to have this information written down somewhere; it's possible to load it from the OpenBoot prompt. Otherwise the only recourse is to make it up (which I'll have to do with a few machines.) So if you happen to have some old Sun kit which hasn't yet suffered amnesia, write down all the information before it disappears! (I'm doing that with the few machines which still retain it; I'll put it on a label underneath or inside.) Fortunately in the 1000E, the system's identity is stored in EEPROM on the control board and is copied into the NVRAM on each system board. I've noted it all anyway, just in case. Failure of the CMOS battery in a PC is somewhat trivial in comparison; it might get mildly tricky with very old machines which have the CMOS configuration utility on floppy. Not something I'd bother writing about... Kat Last edited by Kat Manton; 28th Jun 2011 at 6:19 pm. Reason: Corrected M48xx SRAM sizes. Oops.