>I have an pc532, tht's running minix (last i fired it up) :-)

Wow! A pc532 not running NetBSD :)

>Is the some way that i can buy the newer rom so i can run NetBSD ?

Which ROM do you have?  If you have the auto-boot ROM from around 1991,
you have the most current of which I know.  But even if you don't,
you can run NetBSD.   It will just take a little more effort to get
it booted.  You will have to find the right place on the disk where
the boot program lives and give the proper "read ..." command and
then execute the boot program.  That shouldn't be hard to do.

Get the INSTALL document from the 1.4_ALPHA or 1.4_BETA directories
(BETA if it is there) and try to follow the install procedure.
Then, before you reboot, you need to get the boot information
if you don't have the auto-boot ROM.  (If you do have it, you don't
need the next information.)

run bim

You will get something like:

---->/usr/src/HOME/phil
steelhead[1]# bim

Disk: disk 1   Type: SCSI
Physical Sector Size = 512
Disk Size = 1173930
 partition         type  sector start  length in sectors
     a          4.2BSD         23980             383680
     b            swap          2180              21800
     c         unknown             0            1173930
     d            boot             2               2178
     e          4.2BSD        451260             722670
     f            swap        407660              43600

Boot partition = d
Default boot image  = 0
Boot Images: total of 8
  (image address and size in sectors.)
Image  address   size  load addr  run addr   name
    0        0     32   0x3e6800  0x3e6820   /usr/mdec/boot
    1       32     64   0x3bf000  0x3bf020   /usr/mdec/boot


From this you can easily calculate the disk address of the boot
program and where to load it and run it.  So for the above stuff,
the boot partition starts at sector 2.  The boot image is at
offset 0 in the boot partition.  So the boot program is at
sector 2 and is 32 sectors long.  You need to load it at
address 0x3e6800 and run at 0x3e6820.  Write that information down
for your system and you can then give the proper ROM monitor commands
to load the boot program and run it.  All the autoboot monitor does
is to read that information from the disklabel and the boot images 
table on the first two sectors of the disk.

I hope this helps.

-- 
Phil Nelson                    NetBSD: http://www.netbsd.org
e-mail: phil@cs.wwu.edu        !gifs: http://www.gnu.org/philosophy/gif.html
http://www.cs.wwu.edu/~phil