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BDOS HDBOOT info file

HD BOOT ROM For use with the ATOM hard disk interface.

General Information

The HD BOOT ROM is a version 3.0 Basic ROM which will boot the
DOS from hard disk or floppy disk automatically when the SAM is
turned on or reseted.
This ROM will also reset the SAA sound chip directly after a
reset and defines the funktionkeys F7 as DIR [RETURN] and F8 as
DIR PEEK SVAR 7 [RETURN] instead of the tape commands.

Great care was taken to add these features and keep the ROM
fully compatable with the original 3.0 ROM. For this reason the
original copyright message had to be removed. The copyright
message now will be 'HD BOOT ROM V2' (After NEW and DOS is
already in memory).


When the SAM is turned on or reseted, the SAA sound chip is
reseted and the normal reset procedure is continued. Holding the
SHIFT key down during reset will give you a 256K SAM to work
with. Before the copyright message is printed a test is made if
DOS is in memory and if not it will fool basic that key F9 is
pressed and the DOS is booted.
The BOOT command works in the same manner as before. But now
it boots from hard disk. It is still possible to boot from
floppy disk by holding down the SPACE BAR during reset or by
disabling the hard disks bootsector (see below).


The first sector on the hard disk is the boot sector. This
sector contains a small machine code program to load the DOS
from the boot record and sets some user definable DOS variables.

If the boot sector hasn't been initialized, is disabled or if
there is no bootable DOS in the boot record. The HD BOOT ROM
will try to boot DOS from a floppy disk.
The boot sector is not created by B-DOS. But by a seperate
program called 'MakeBoot' You will find it on the B-DOS disk.


To make the hard disk bootable the following has to be done:

1) Replace the SAM ROM with the HD BOOT ROM

2) Make a boot record.
   A boot record is nothing more than a record containing a DOS
   at the start of a record. Just as with a bootable floppy disk
   Any Record can be used to make a boot record. But record one
   is recommended because it's faster.
   To make sure the DOS will be at the biginning of a record,
   use a empty record. When the record isn't empty. The files in
   it can be copied to a other record and then be erased, copy
   B-DOS to it and copy the files back to the record.
   In most cases copying and erasing the first file in a record
   will work too.

3) Initialise boot sector with the 'MakeBoot' program.
   This program is supplied on the B-DOS disk. This program
   shows the boot sector status, boot record status, HD boot
   status, some default DOS settings which can be altered and
   ofcourse creates the boot sector. More details can be found
   within this program.


Once power has been switched on and the hard disk has finished
its self test / initialization. The HD BOOT ROM will boot from
hard disk.

Sometimes after the power is switched on, it may happen that the
HD BOOT ROM boots from floppy instead of hard disk once in a
while. When this happens just press the reset button.


Disconnect all leads from the SAM and turn it upside down and
removo all screws (except those at the plastic label in the
middle). Remove the floppy disk and turn it again).
Now lift the keyboard about a cm and then pull it a cm forwards
(front side). Now you can lift the front side just far enough
to put your hand between it. Before doing so have a look.
You can see two green keyboard leads. One in the middle and one
to the right. Pull the one in the middly out of its connector
first. After that you can lift the top a bit more so you can
reach the other lead. Pull it out also.
After both leads are removed. You can lift the top and put it
in a save place.
Just above the middle keyboard connector you can see the SAMs
ROM. Remove it by using a small screw driver as a wrench.
Put the screw driver at the a side of the ROM and push it
Slightly so the ROM gets loose from its socket. Do it also
at the otherside and repeat this until the ROM is out of it
Now take the HD BOOT ROM and put it in the ROM socket. Make
sure the ROM is placed with the small notch pointing to the
ASIC (black square chip with VLSI in it).
After this re-assemble the SAM.

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