True Blue PC/AT Turbo board by Megahertz

From: jpero_at_cgo.wave.ca <(jpero_at_cgo.wave.ca)>
Date: Fri Mar 27 18:48:27 1998

> Overclocking another retrorevionistpc idea.
Heh...just for fun value usually.
>
> No most likely it allowed you to buy the fastest 286 and clock it at it's
> native speed.

Right, that is best way. What I would do: find a PLCC socket and a
spare 286 12mhz CPU and plug them all in. Did that either way on
same pinout of either PGA oe PLCC packages. I liked especially
Harris C286 chips. Runs very cold even at full power. :) Simens is
HOTTEST, ow!


> < piggy-backed RAM chips. It has lots of "ECOs" on the pin side of
> < the board. I don't know if my other one does, too. Note: ECO =
> < Engineering Change Order.)
>
> The AT might go a little faster, at some point the DRAM timing goes flakey
> and otehr things start to get cranky.
>
> That's especially true of the ISA cards!

There was changes to bios to block o/c and that is why this device
went around this either by manual after post test or automatic.
Start up the machine at normal mhz, after post, crank up the clock
rate.

NOT really! the 14.38181mhz thingy take care of DMA, irq's and
ISA. In newer boards some changes the clock rate on the ISA by that
area also that o/c the whole ISA shebang. But the problem is with 2
specific chips that splits the clock feeds sometimes are rated at
specific clock rate.

>
> <2) Would increasing the 286-6 to a 286-8,10,12 increase the frequency
> < at which it could reliably run? I have a PGA 286-8, but I'm not
> < sure there are faster PGA 286s?
>
> There are it went all the way to 12 or 16mhz. I have a LCC version thats
> 12 and the PS/2m50s I have are 10mhz.
>
> <3) Any software needed? (The ROMs appear to be the same as on my other
> < machine.)
>
> None but the rams may get unhappy of pushed to fast (data takes time to
> get out).
Simply: change out those ram with lower nS rating using 256K x 1
chips for either type 1 or 2 motherboard. I did that for fun!
I preferred AT type 2 for compactness and low wait states, plug
either 100ns or 80ns ram, change cpu for 12mhz and watch the
operation. Someting might go cranky or you get a bit faster machine
but not by long shot.

That is why I prefer Model 50Z for no o/c required total package and
well tuned performance even I did not own one YET. I have a 286 12
motherboard 1' square clone that feels like type 1 8mhz board even
with fast ram. YUK.

Jason D.

PS: I wondered why I got a dud 286-8 cpu by IBM when I was given
boxful of junk parts. Don't think it was by o/c but CPU failures
how rare that are! :)

>
> Allison
 
email: jpero_at_cgo.wave.ca
Pero, Jason D.
Received on Fri Mar 27 1998 - 18:48:27 GMT