VOGONS


First post, by Arvid

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I recently bought a Olivetti M300-30, when I booted it up I found that the BIOS battery was dead. Opening up the case it turns out to be a Dallas RTC chip inside, luckily it is socketed so it was easy to remove. I ordered a new one from RS Online (it was a DS12887A), they had several different version so I just randomly picked one because I could not tell any difference from the info provided and they were not very expensive so I wanted to give it shot. When I installed the new one it works...kind of. It´s able to remember time and date and other settings adter being switched off but it boots extremely slowly and the memory counting at boot in addition to being slow is not able to detect all the memory. It only found 512kb of the 640kb base memory. In addition it will not find what is called Dedicated memory (see suplied screenshot) at all. I have no idea what this dedicated memory is?
How do I find out which Dallas RTC chip I need to get this system working correctly again? There seems to be many variants of the DS12887A chip.

To make things more confusing I found this document https://secure.corradoroberto.it/doc/olivettt … tems1/cap36.pdf for the M300-30 and this lists the RTC chip as a MCCS14681. Googling this number it seems to be a motorola chip with pretty much the same function as a Dallas chip.

This is the original chip:

20191030_185152.jpg
Filename
20191030_185152.jpg
File size
276.9 KiB
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499 views
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Original Dallas chip
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Fair use/fair dealing exception

The new chip I bought:

20191118_102119.jpg
Filename
20191118_102119.jpg
File size
185.52 KiB
Views
499 views
File comment
The new chip I bought
File license
Fair use/fair dealing exception

Boot screen:

20191118_103448.jpg
Filename
20191118_103448.jpg
File size
452.2 KiB
Views
499 views
File comment
Boot screen
File license
Fair use/fair dealing exception

Reply 1 of 11, by computerguy08

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Is it still misbehaving like that with the old Dallas chip (just to make sure the new RTC is the culprit) ?

Looking for a motherboard? You can find it in Ultimate Hardware 2019: http://www.win3x.org/uh19/motherboard/search
Join our UH19 Discord server here: https://discord.gg/HWWH7hsk2p

Reply 2 of 11, by derSammler

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There should be a "clear CMOS" jumper somewhere on the board which must be closed once after having replaced the Dallas chip. This will zap the contents of the Dallas chip and makes sure that there is no data that the BIOS may interpret wrongly.

Reply 3 of 11, by Arvid

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computerguy08 wrote:

Is it still misbehaving like that with the old Dallas chip (just to make sure the new RTC is the culprit) ?

When I inserted the old RTC things work like they should apart from the fact that no settings are saved since the battery is dead.

derSammler wrote:

There should be a "clear CMOS" jumper somewhere on the board which must be closed once after having replaced the Dallas chip. This will zap the contents of the Dallas chip and makes sure that there is no data that the BIOS may interpret wrongly.

That´s a good suggestion, I hadn´t thought of that. I checked the documentation I found online and there is indeed such a jumper. I´ll not be able to check this in almost 2 weeks because of work but I´ll give it a shot as soon as possible 😀

Now for another thing with this PC. Whenever the configuration is wrong, such as incorrect number of floppy/hard drives installed it will automatically boot into the BIOS. However I can see no way to do this manually if everything works like it should. Does anyone know how this works? It does not have a regular BIOS like most computers, instead it seems that the BIOS setup is loaded from a hidden partition on the hard drive. I think perhaps some sort of special setup floppy disk is needed for this?

Reply 4 of 11, by Arvid

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Just a small update for posterity in case anyone else has similar problems. The clear CMOS jumper was indeed there on the motherboard but it wasn´t actually a jumper, just 2 solder points that could be shorted. I spent some time fiddling with back and forth of Dallas chips and clearing the CMOS to no avail, still memory problems and extremely slow booting. In the end I found out that the dedicated memory is probably for the "shadow BIOS and Video RAM" options in the BIOS, after setting these to on everything worked just fine and now it boots fast like it should and no ugly beeping from the PC speaker.

I also bought a replacement Dallas chip with replaceable battery from Glitchworks for ease of battery replacement down the line: https://www.tindie.com/products/glitchwrks/gw … acement-module/

As for being able to enter the BIOS that can be done by pressing CTRL+ALT+U while the message "Region ID delay" is showing while counting down from 5, and I was also able to make a new boot/setup disk from the BIOS so now I have the neccesary tools in case the hard drive should die. The BIOS/setup program is located on a hidden partition so that disk is indeed very important as a backup 😲

Reply 6 of 11, by Kotu Koylu

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Arvid wrote on 2019-11-20, 16:17:
I recently bought a Olivetti M300-30, when I booted it up I found that the BIOS battery was dead. Opening up the case it turns o […]
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I recently bought a Olivetti M300-30, when I booted it up I found that the BIOS battery was dead. Opening up the case it turns out to be a Dallas RTC chip inside, luckily it is socketed so it was easy to remove. I ordered a new one from RS Online (it was a DS12887A), they had several different version so I just randomly picked one because I could not tell any difference from the info provided and they were not very expensive so I wanted to give it shot. When I installed the new one it works...kind of. It´s able to remember time and date and other settings adter being switched off but it boots extremely slowly and the memory counting at boot in addition to being slow is not able to detect all the memory. It only found 512kb of the 640kb base memory. In addition it will not find what is called Dedicated memory (see suplied screenshot) at all. I have no idea what this dedicated memory is?
How do I find out which Dallas RTC chip I need to get this system working correctly again? There seems to be many variants of the DS12887A chip.

To make things more confusing I found this document https://secure.corradoroberto.it/doc/olivettt … tems1/cap36.pdf for the M300-30 and this lists the RTC chip as a MCCS14681. Googling this number it seems to be a motorola chip with pretty much the same function as a Dallas chip.

This is the original chip:
20191030_185152.jpg

The new chip I bought:
20191118_102119.jpg

Boot screen:
20191118_103448.jpg

Dear friend could you upload setup disk image or system utilities here? i have m300-30/p with dead dallas as yours.please

Reply 8 of 11, by Kotu Koylu

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Thanks for files to Olivrea.de site admin Heiko.He has got a big olivetti archive.

Attachments

  • Filename
    User diskettes.zip
    File size
    791.38 KiB
    Downloads
    15 downloads
    File comment
    m300-30 m300-30/p user diskettes
    File license
    CC-BY-4.0
  • Filename
    m30030bi.zip
    File size
    90 KiB
    Downloads
    14 downloads
    File comment
    m300-30/p bios update file
    File license
    CC-BY-4.0

Reply 10 of 11, by Kotu Koylu

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Arvid wrote on 2020-07-31, 15:35:

Sorry for not answering here, haven´t been to Vogons for some time now. It seems you found what you needed after all without my help?

If you have original hdd image it would be great.With ghost or acronis like image utility. 😀 ı found original diskette images ( Imagedisk format)

Reply 11 of 11, by Arvid

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Kotu Koylu wrote on 2020-07-31, 19:03:

If you have original hdd image it would be great.With ghost or acronis like image utility. 😀 ı found original diskette images ( Imagedisk format)

I believe I made a image with Ghost earlier, I´ll try to remember to check in two weeks time when I´m home again 😀