ir230@sdcc6.ucsd.EDU (john wavrik) (04/22/88)
I recently installed minor upgrades to both my BIOS ROM and to the DOS in my computer. The new BIOS arrived several weeks before the DOS, so I was able to notice some bugs caused by the incompatibility. When the DOS upgrade arrived, I changed the attributes on the hidden files to make them normal on both the hard disk and distribution disk, and I then copied them from the distribution disk to the hard disk using COPY. I also copied COMMAND.COM and all of the external command files which interested me. A file comparison program showed that the copies were the same as on the distribution disk. I then changed the attributes on the hidden files to what they were originally. The bugs were still there. At this point, I remembered the SYS command -- after I used SYS, everything was fine. I'm curious as to what SYS does other than what I tried to do by hand. Isn't the DOS determined (internally) by the two hidden IBMxxx.COM files and COMMAND.COM? It's obvious that SYS is quicker -- but why is it essential? Is there something that Peter Norton didn't tell me? As a further (potential) problem, I find that the manual says that SYS will not work if the new system is bigger than the old. What happens if I want to install DOS 3.3, rather than just an upgrade of DOS 3.2, on a hard disk full of files? J J Wavrik UCSD.
anderson@vms.macc.wisc.edu (04/22/88)
In article <3689@sdcc6.ucsd.EDU>, ir230@sdcc6.ucsd.EDU (john wavrik) writes... ] As a further (potential) ] problem, I find that the manual says that SYS will not work if the new system ] is bigger than the old. What happens if I want to install DOS 3.3, rather than ] just an upgrade of DOS 3.2, on a hard disk full of files? You're right, that will be a problem. I've just gone through it. I asked for net.assistance on that and another related point and received lots of helpful responses. I'm about to post a summary, so stay tuned, should be along in a couple days. ==Jess Anderson======(home:)========INTERNET: anderson@vms.macc.wisc.edu==== | 1210 W. Dayton 2838 Stevens UUCP: {harvard,rutgers,allegra,ucbvax} | | Madison, WI 53706 Madison 53705 !uwvax!vms3.macc.wisc.edu!anderson | ==608/263-6988=======608/238-4833===BITNET: anderson@wiscmacc===============
leonard@bucket.UUCP (Leonard Erickson) (04/26/88)
In article <3689@sdcc6.ucsd.EDU> ir230@sdcc6.ucsd.EDU (john wavrik) writes:
< I'm curious as to what SYS does other than what I tried to do by hand. Isn't
< the DOS determined (internally) by the two hidden IBMxxx.COM files and
< COMMAND.COM? It's obvious that SYS is quicker -- but why is it essential? Is
< there something that Peter Norton didn't tell me? As a further (potential)
< problem, I find that the manual says that SYS will not work if the new system
< is bigger than the old. What happens if I want to install DOS 3.3, rather than
< just an upgrade of DOS 3.2, on a hard disk full of files?
At boot time, the ROM bios loads the BIOS and DOS from the boot disk. Until they
are loaded, the directory isn't readable (as they contain the code to read it!).
So the ROM BIOS has to be able to find those two files. The simplest, most
reliable method is to have the boot sector tell where they start (right after
the FAT and root directory) and have thenm in ONE CONTIGOUS BLOCK following
this point.
So when you copied the files, they went into the first free clusters on the HD
and *then* the clusters used by the old copies went away. SYS copies them on
top of the old files and in a contigous block as well.
The need for the clusters to be contigous explains why sysing a larger system
won't work. With a bit of work it is possible to remove the files (or worse
yet directories) that are occupying the needed space. The only time I've had
to deal with this, I did a SYS and then removed the hidden and system
attributes. I then used a disk optimizer (yes, I *know* this is a kludge!).
Then I set the bits back. It worked. Your mileage may vary....
--
Leonard Erickson ...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I used to be a hacker. Now I'm a 'microcomputer specialist'.
You know... I'd rather be a hacker."