Anonymous Coward
Veteran Member
I was a little skeptical about this at first, but while looking for information on high density controllers I stumbled on a conversation about a BIOS extension for PC/XTs that allows you to use high density (1.44, 1.2MB) diskettes in systems that equipped with floppy controllers that support the higher rates. Apparently it works with the 16-bit AT controllers that support 8-bit mode. The program is called 2M, and it comes with a TSR called 2M-XBIOS. It looks quite promising. I do not have my XT with me for testing, but I was hoping someone else could. While this method would not allow for booting from 1.44meg drives, I still think it would be quite practical for people who cannot find the HD controllers with BIOS.
Below is some information I found from the newsgroups:
Try the 2M30.ZIP utility. This program is mainly for formatting 3 1/2 disks to
1.88M extended format (1.5M for 5 1/4 inch). But it has a utility for BIOS
extension that is supposed to support the new drive formats on old PC:s. these
utilitys are named 2M-ABIOS and 2M-XBIOS.
Another utility in the same package is 2MX. Maybe something in this package
will work.
You can get 2M from:
FTP Address (Country) Directory Files
------------------------- --------------------- -------
ftp.gui.uva.es (Spain) pub/pc/2m 2m*.zip
oak.oakland.edu (USA) SimTel/msdos/diskutil 2m*.zip
garbo.uwasa.fi (Finland) pc/format 2m*.zip
-------------------- excert from the info file in 2M -----------------------
Although 2M was initially designed for AT and above computers, from 1.2
release it has gone with a PC/XT release: 2MX. The unique requirement is that
system must be equiped with high density diskette controller and drives. Some
modern small subnotebook computers are ready to connect an external high
density disk drive. Other relatively recent PC/XT systems are provided with
high density drives and a BIOS with high density support, but the disk drive
is a double density one and user can replace it. Finally, in oldest systems
which aren't classified in any of these categories, their owner can replace
both the double density drives and controllers with new high density ones;
this hardware may be used in the future in a new AT system (so, it is a very,
very cheap option and also a good investment).
Since it is difficult to find in the market nowadays high density
controllers for PC/XT systems, if needed, the user can install an AT one. In
2MX tests, I needed to insert a 16 bit card in a 8 bit slot. The card was a
IDE multi-io; however, the high half of bus (which can not be inserted since
the slot is a 8 bit one) is only used to access IDE hard disk, and can be
disabled by a jumper although this also was unnecessary. The logic for
diskette drives, serial and parallel ports was completely functional, since it
only uses the low half of slot.
The main problem is located in PC/XT BIOS, in 99% of cases it is not
capable to support high density. The solution in these systems is to load a
more modern BIOS helped by 2M-XBIOS.EXE, the terminate and stay resident
program which emulates AT AMI BIOS in XT computers. In fact, 2MX requests the
user to install this driver when it can't detect diskette drive types (this
is normal when BIOS is old and don't report diskette types). However, in some
modern PC/XT systems perhaps 2MX will be loaded without needing 2M-XBIOS. If
in this case there is some malfunction in drives, try to also load 2M-XBIOS.
2MX and 2M-XBIOS need a IBM compatible machine; I can say that both
programs have been tested in an original IBM PC 4.77, in a PS/2-30 8086 system
and at the moment are in service in some oriental clones. As it usually
happens, some trademark PC/XT systems are not sufficiently compatible; also,
some systems have diskette drive controllers in the motherboard, which can't
be replaced. You only can be sure that your system is compatible after trying
2MX and 2M-XBIOS; the 2M author can't know this before and also can't do
anything if system is not compatible. If your system is an oriental clone it
is almost sure that will be sufficient compatible; if it is a trademark one
(except IBM) it might not to be.
Below is some information I found from the newsgroups:
Try the 2M30.ZIP utility. This program is mainly for formatting 3 1/2 disks to
1.88M extended format (1.5M for 5 1/4 inch). But it has a utility for BIOS
extension that is supposed to support the new drive formats on old PC:s. these
utilitys are named 2M-ABIOS and 2M-XBIOS.
Another utility in the same package is 2MX. Maybe something in this package
will work.
You can get 2M from:
FTP Address (Country) Directory Files
------------------------- --------------------- -------
ftp.gui.uva.es (Spain) pub/pc/2m 2m*.zip
oak.oakland.edu (USA) SimTel/msdos/diskutil 2m*.zip
garbo.uwasa.fi (Finland) pc/format 2m*.zip
-------------------- excert from the info file in 2M -----------------------
Although 2M was initially designed for AT and above computers, from 1.2
release it has gone with a PC/XT release: 2MX. The unique requirement is that
system must be equiped with high density diskette controller and drives. Some
modern small subnotebook computers are ready to connect an external high
density disk drive. Other relatively recent PC/XT systems are provided with
high density drives and a BIOS with high density support, but the disk drive
is a double density one and user can replace it. Finally, in oldest systems
which aren't classified in any of these categories, their owner can replace
both the double density drives and controllers with new high density ones;
this hardware may be used in the future in a new AT system (so, it is a very,
very cheap option and also a good investment).
Since it is difficult to find in the market nowadays high density
controllers for PC/XT systems, if needed, the user can install an AT one. In
2MX tests, I needed to insert a 16 bit card in a 8 bit slot. The card was a
IDE multi-io; however, the high half of bus (which can not be inserted since
the slot is a 8 bit one) is only used to access IDE hard disk, and can be
disabled by a jumper although this also was unnecessary. The logic for
diskette drives, serial and parallel ports was completely functional, since it
only uses the low half of slot.
The main problem is located in PC/XT BIOS, in 99% of cases it is not
capable to support high density. The solution in these systems is to load a
more modern BIOS helped by 2M-XBIOS.EXE, the terminate and stay resident
program which emulates AT AMI BIOS in XT computers. In fact, 2MX requests the
user to install this driver when it can't detect diskette drive types (this
is normal when BIOS is old and don't report diskette types). However, in some
modern PC/XT systems perhaps 2MX will be loaded without needing 2M-XBIOS. If
in this case there is some malfunction in drives, try to also load 2M-XBIOS.
2MX and 2M-XBIOS need a IBM compatible machine; I can say that both
programs have been tested in an original IBM PC 4.77, in a PS/2-30 8086 system
and at the moment are in service in some oriental clones. As it usually
happens, some trademark PC/XT systems are not sufficiently compatible; also,
some systems have diskette drive controllers in the motherboard, which can't
be replaced. You only can be sure that your system is compatible after trying
2MX and 2M-XBIOS; the 2M author can't know this before and also can't do
anything if system is not compatible. If your system is an oriental clone it
is almost sure that will be sufficient compatible; if it is a trademark one
(except IBM) it might not to be.