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I overclocked my IBM 5150...

This is awesome and godspeed!
I am looking forward to your progress and really just glad to see some progress on this topic of conversation
 
Check out minus zero degreree for ram charts and specs. That's how I found the 100ns I'm using currently
 
24.576mhz immediately caused the system to hang... moving down to a 24mhz crystal now... will let y'all know how it goes in a bit!
 
Ok, the 24mhz does the same thing... freezes immediately when I enable the turbo... I have another thing to try though... If it's a ram speed issue, I currently have the Lo-tech 1MB ram board in the system, but I'm using the ram on the motherboard vs. the ram on the card... I wonder if I can bypass the ram on the motherboard and if that helps at all... hmmmmm
 
I suppose that the 10/27/82 bios actually prevents me from doing what I was thinking now that I look at the docs... Maybe someone more knowledgable than me can confirm?
 
I remember reading somewhere that those ram banks just need to be "filled" but not necessarily with ram. Perhaps jumpering the banks to close the circuit can by pass the error code
I haven't tried this my self yet but could look into further.I have a sacrificial board to play with.
 
clifford said:
I remember reading somewhere that those ram banks just need to be "filled" but not necessarily with ram. Perhaps jumpering the banks to close the circuit can by pass the error code
I haven't tried this my self yet but could look into further.I have a sacrificial board to play with.
Click to expand...
<- info re: the BIOS bug...
 
Only Bank 0 which is 150ns... I still can't figure out what the other 3 banks have in them and google isn't producing any hits at all... Mystery chips!
 
I'd try over clocking with just the soldered bank of known speed ram and see where that gets you. If performance increases than you know the other banks are the problem
 
I think that's the issue though, like I can't actually disable those banks due to the bug...
 
Should be able to set switches to 256k and just have first row populated
 
Ya, seems like the soldered ram is probably the issue at the moment...
 
Could always try piggy backing faster ram on top of the soldered... Sort of quick and dirty experiment before desoldering.
 
Looking at the other chips that are in the sockets, some are clearly 200ns which won't cut it... also seems that I probably can't feasibly push the system beyond where 100ns would even matter... 100ns would work w/ 10mhz hypothetically which I don't think is realistic... eBay here I come!
 
Ok, just bought 50 KM4164B-10 chips... will take a few weeks to get here though... meanwhile I'll pivot to some other work on the computer!
 
c00gr said:
Only Bank 0 which is 150ns... I still can't figure out what the other 3 banks have in them and google isn't producing any hits at all... Mystery chips!
Click to expand...
I once had a system with 256k and bad chips in every bank.

I didn’t have spare 64k chips and desoldering then used 16k chips instead then installed a memory card and everything worked .

Not sure what controls density but hopefully it’s one of the few situations where it detects on its own.
 
c00gr said:
If it's a ram speed issue, I currently have the Lo-tech 1MB ram board in the system, but I'm using the ram on the motherboard vs. the ram on the card... I wonder if I can bypass the ram on the motherboard and if that helps at all... hmmmmm
Click to expand...
All four RAM banks on the 5150 motherboard are permanently enabled. Therefore, you need to populate all four banks before adding a RAM card (which would be used to complement motherboard RAM). Note that, per [here], removing the RAM chips from a bank will not disable the bank.
 
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