[comp.sys.ibm.pc.misc] Bios upgrade help needed

endter@pioneer.arc.nasa.gov (Bill Endter RCU/DEC) (04/02/91)

	   I am looking into upgrading the bios on my 386 system so I 
	can add a larger hard disk.  The current bios is Phoenix V3.06
	dated 1985,1986.  My system board is made by UNITRON and called a
	Mini 386 system.  It uses the Chips and Technologies chip set.
	   I am very confused about bioses and need some answers.  Will 
	any 386 bios probably work on this board?  I know the bios I have
	is on less dense chips (128kb) and requires a setup disk to set 
	parameters.  The newer bioses I have seen are on 256kb chips.
	Will these work, or is a change required on the mother board?  Do
	companies sell upgraded bioses on the lower density chips?
	   Also, I know that some companies use a modified bios.  Is there 
	any way to tell if the bios has been modified?  My system has been 
	very stable and I have never had any incompatibilty problems.

		Thanks,

		Bill

Kevin.Gmyrek@p5.f121.n324.z1.FIDONET.ORG (Kevin Gmyrek) (04/02/91)

 >         I am looking into upgrading the bios on my 386 system so I
 >      can add a larger hard disk.  The current bios is Phoenix V3.06
 >      dated 1985,1986.  My system board is made by UNITRON and called a
 >      Mini 386 system.  It uses the Chips and Technologies chip set

Well first off I assume that you need to upgrade your BIOS because 
your drive types supported by the BIOS don't support the larger 
drives, right?  If I recall correctly 3.06 is not an *excessively* 
antique version of the Phoenix BIOS.

 >         I am very confused about bioses and need some answers.  Will
 >      any 386 bios probably work on this board?  I know the bios I have

If the machine is a TRUE clone any BIOS should work.  If there's some 
custom hardware or other strange configuration on the board you might 
need a custom BIOS.  I've had much success with upgrading BIOSs on 286 
machines.

 >      is on less dense chips (128kb) and requires a setup disk to set
 >      parameters.  The newer bioses I have seen are on 256kb chips.
 >      Will these work, or is a change required on the mother board?  Do
 >      companies sell upgraded bioses on the lower density chips?

One major concern in using 256Kb chips vs. 128Kb ones is that the 
motherboard is set to read the entire chip.  Many boards have a jumper 
for 128K/256K ROM selection... you might want to check for one.  If 
not (assume you can't use the 256K chips) you can probably the 
contents of the 256K chips into a 128K ROM.  I haven't found a BIOS 
yet that takes more than 64Kb or so eventhough it's in a 128K ROM. 

 >         Also, I know that some companies use a modified bios.  Is there
 >      any way to tell if the bios has been modified?  My system has been
 >      very stable and I have never had any incompatibilty problems.

???  You're on your own here.  I don't really see the concern.

                                             Good luck,
                                             Kevin

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