Pretty awesome project I’d like to make one of these on one of those clear colored macs one day. That would be pretty awesome.

Chkcpu wrote on 2023-06-29, 19:50:

Hi lunarApple, […]
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Hi lunarApple,

A multiplier of 6.5x or higher does not exist on any Socket 7 CPU, but all K6-2CXT models, like your K6-2/450, and all K6-III, K6-2+, and K6-III+ CPUs do support the 6.0x multiplier.
Just set the multiplier at 2.0x and you will get 6.0x. This works because the 2.0x setting on these CPUs is internally remapped to 6.0x. 😉

However, the stock BIOS for the OPC620 card doesn’t support the 6.0x multiplier, so you will need to install my patch J.1 version for that.
Sorry that the old direct link to this OPC620J1 BIOS is broken. I had to move my website to a new domain. The new link to this patched BIOS is: http://www.steunebrink.info/bios/OPC620J1.zip

Cheers, Jan

Nice! Thank You. I shall give it a go then.

dr.zeissler wrote on 2021-09-08, 15:52:

Thx, I can mount the drive, I got the drive-letter but if I want to access it I always get an error and the drive is not accessed. I have to try again and make a screenshot.

BTW I know it's been 2 years so you probably don't care any-more but I found a solution for the problem. I was having the same error on my 6400 mobo + 600i cd-rom:

Here is what I posted on another forum:

"I found an app "SCSI Probe 5.2" When the CD-ROM does not work, I have to go back on the mac side and manually mount the CD through that app, then it will start to be accessible on the x86 side.

Also I found these:

http://web.archive.org/web/20180822093828/htt … 0Micro/misc.zip
https://web.archive.org/web/20130416073257if_ … ePC%20Drive%20D
https://web.archive.org/web/20130416021726if_ … y%20Install.dmg

I think these drive images include a pre-installed Windows 98, although after I was able to get the CD working I just installed W98SE from the normal OEM CD and included with OrangePC 3.4 win98 bootdisk image.
"

Chkcpu wrote on 2023-06-29, 19:50:

Hi lunarApple, […]
Show full quote

Hi lunarApple,

A multiplier of 6.5x or higher does not exist on any Socket 7 CPU, but all K6-2CXT models, like your K6-2/450, and all K6-III, K6-2+, and K6-III+ CPUs do support the 6.0x multiplier.
Just set the multiplier at 2.0x and you will get 6.0x. This works because the 2.0x setting on these CPUs is internally remapped to 6.0x. 😉

However, the stock BIOS for the OPC620 card doesn’t support the 6.0x multiplier, so you will need to install my patch J.1 version for that.
Sorry that the old direct link to this OPC620J1 BIOS is broken. I had to move my website to a new domain. The new link to this patched BIOS is: http://www.steunebrink.info/bios/OPC620J1.zip

Cheers, Jan

Ok so I tried the modified bios just now and at a 2x multiplier I am getting 256mhz on a K6-2/450AFX

Check it with software, don’t trust the bios reading. Sometimes the bios doesn’t have the correct speed detection. CHKCPU might be able to adjust that?

If you pull bf0 and bf1 correctly, the CPU WILL be at 6x this is done in the cpu. So if you have 66mhz fsb and pull bf pins correctly, you will have 400 mhz guaranteed. 75mhz fsb will be 450 mhz and 83 fsb will be 500mhz the only exception would be on + cpus where the multi can be overridden in software after boot

CHKCPU, SetMul and similar utilities displays the correct CPU clock frequency. Whatever is displayed on the POST screen isn't relevant if everything is fine afterwards.

lunarApple wrote on 2023-06-29, 23:42:

Ok so I tried the modified bios just now and at a 2x multiplier I am getting 256mhz on a K6-2/450AFX

Other OPC620 users reported the same erroneous 256MHz indication when using the 2.0x = 6.0x multiplier setting on the stock BIOS with a K6-2 or K6-III. However the patched BIOS indicates the correct CPU speed here, so something didn’t go well when installing the patched BIOS and I believe you are still running the stock one. 😉

Copying the patched BIOS at the correct position into the BIOS file of the OrangePCi application is a bit tricky. Earlier in this thread user Nathan_A wrote a nice tutorial on how he did that.

Did you use a similar technique or do you use another method when updating the BIOS. Just curious. 😀

Cheers, Jan