We probably should have a FAQ for this as it keeps coming up. Here are some starting points ..
IBM PC 5150:
Summary:
5150 BIOS Revisions:
This is a quick summary of the BIOS revisions for the 5150. The details can be found in this post:
http://www.vintage-computer.com/vcforum/showthread.php?t=9692
BIOS Notes:
Motherboard differences:
All PC 5150 motherboards have two sets of DIP switches for memory and device configuration.
IBM PC XT 5160:
Summary:
5160 BIOS Revisions:
This is a quick summary of the BIOS revisions for the 5160. The details can be found in this post:
http://www.vintage-computer.com/vcforum/showthread.php?t=9693
BIOS Notes:
IBM PC 5150:
Summary:
- Introduced in 1981
- Five slots on the motherboard
- Cassette port on the motherboard
- Early models have up to 64K on the motherboard; later models have a 256K motherboard
- Small power supply: 63 watts
- No hard disk offered by IBM or supported; need to use an expansion chassis
- Floppy controller has external connector for 2 more floppies
5150 BIOS Revisions:
This is a quick summary of the BIOS revisions for the 5150. The details can be found in this post:
http://www.vintage-computer.com/vcforum/showthread.php?t=9692
Release 1: 04/24/81
Release 2: 10/19/81
Release 3: 10/27/82
Release 2: 10/19/81
Release 3: 10/27/82
BIOS Notes:
The first two BIOS versions have a bug that prevent the machine from recognizing more than 544KB. The first two versions also do not scan the ROM BIOS areas for ROM BIOS extensions, so they can not be boot from a hard disk, use an EGA or VGA card, or make use of any device that is dependent upon a ROM BIOS extension.
The third version of the BIOS adds support for adaptors have that ROM BIOS extensions. Without this support, these machines can't boot from a hard disk, use an EGA or VGA card, or boot over a network. This BIOS was offered as an upgrade to owners of older machines.
All BIOS versions are 40KB in size. Chip U33 has the 8KB of BIOS. Chips U29-U32 (8KB each) hold BASIC.
All used the 'ID Byte' of FF. None had a 'Sub-model Byte'
The third version of the BIOS adds support for adaptors have that ROM BIOS extensions. Without this support, these machines can't boot from a hard disk, use an EGA or VGA card, or boot over a network. This BIOS was offered as an upgrade to owners of older machines.
All BIOS versions are 40KB in size. Chip U33 has the 8KB of BIOS. Chips U29-U32 (8KB each) hold BASIC.
All used the 'ID Byte' of FF. None had a 'Sub-model Byte'
Motherboard differences:
- Revision one (PC1) machines have a minimum of 16KB on the motherboard, which is expandable to 64KB.
- Revision two (PC2) machines have a minimum of 64KB on the motherboard, which is expandable to 256KB.
All PC 5150 motherboards have two sets of DIP switches for memory and device configuration.
IBM PC XT 5160:
Summary:
- Introduced in 1983
- Eight slots on the motherboard
- No cassette port on the motherboard - ever
- Larger power supply: 130 watts?
- Hard drive capable without an expansion chassis; usually 10 or 20MB
- Floppy controller has external connector for 2 more floppies
- Only one DIP switch bank on the motherboard for configuration
5160 BIOS Revisions:
This is a quick summary of the BIOS revisions for the 5160. The details can be found in this post:
http://www.vintage-computer.com/vcforum/showthread.php?t=9693
Release 1: 11/08/82
Release 2: 01/10/86
Release 3: 05/09/86
Release 2: 01/10/86
Release 3: 05/09/86
BIOS Notes:
The first revision BIOS (11/08/82) has all of the features of the 10/27/82 IBM PC 5150 BIOS. This version was used on the 64/256K motherboards.
The second revision BIOS (01/10/86) added support for the new IBM Extended keyboard and 80 track floppy drives. High density floppies might also be supported by the BIOS, but it is unknown if it works because the hardware that IBM shipped did not have a high density data rate.
The second revision BIOS (01/10/86) added support for the new IBM Extended keyboard and 80 track floppy drives. High density floppies might also be supported by the BIOS, but it is unknown if it works because the hardware that IBM shipped did not have a high density data rate.
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