VOGONS


First post, by Kekkula

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So I got this machine, after finding no information about Osborne machine I opened it up and found out that its the same machine as commodore pc50.

Machine didn't have memory and strangely all ribbon cables were removed. After installing some memory and cables, even the original 40mb hardrive started working.
I replaced hardrive with xt-ide and issue I'm having is that bios has some kind of auto detect routine and always when I start or even soft reboot the machine it tries to detect the hardrive and fails after around two minutes, then I have to enter bios and set drive to none and reboot then machine works just fine. It always tries to set the drive to type36. I replaced bios battery and bios seems to retain other settings time, date... etc.
I'm thinking I should test commodore bios and see if the problem persists.

Another feature of the bios is that it can set ems memory size and address, it doesn't work without specific driver I think, because if I set it, it just shrinks memory size and emm386 cannot use it.
I have to poke around original hardrive and see if it has the driver, although the retroweb has commodore driver.

Reply 1 of 5, by Kekkula

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I tested commodore pc50 bioses from the retroweb, but I couldn't get those working.
Files are 128k so I tried to split files to two 64k files, even and odd. But only got black screen no matter what order I tried.
Is there any emulator that I could try? Because I don't know if the files are working at all.

Reply 2 of 5, by Kekkula

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It turned out being my xt-ide card with 386 bios that was preventing system to boot normally. After changing to at bios system boots normally.
I washed the board and may test if it overclocks before I assemble it back.
I think I have 40mhz crystal and I probably located the original 36mhz crystal on board.

Reply 3 of 5, by Kekkula

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Well 20Mhz seems to work but 25Mhz doesn't boot to dos. Maybe dropping to 1 waitstate would help, but it would probably eat the benefits.

Reply 4 of 5, by pentiumspeed

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C&T CHIPS chipsets is what holds you back as they were often stamped with maximum MHz. Even that, if trying to tune up bios settings falls on it's nose too. Back in the day, I had 386DX with C&T chipset exactly that same issue.

Cheers,

Great Northern aka Canada.

Reply 5 of 5, by Kekkula

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20Mhz is good enough for me.
I would like to test speed difference on different platforms. I've got 486SX@20Mhz but years ago I destroyed one 286 board while trying to overclock it.
So I only have 286 16 Mhz system to tinker with.