minuszerodegrees.net

Images of BIOS ROM's for
IBM 5150/5155/5160/5162/5170

IBM 5150  (IBM PC)

The BIOS is contained in chip U33.
There were three revisions of the BIOS.

Image of 04/24/81 revision     (8 KB, the size of U33) (IBM part number 5700051)
Image of 10/19/81 revision     (8 KB, the size of U33) (IBM part number 5700671)
Image of 10/27/82 revision     (8 KB, the size of U33) (IBM part number 1501476)

Note that the files in the above links are for the BIOS only (chip U33). Cassette BASIC (chips U29 to U32) is not included.

The 10/27/82 revision of BIOS has two known variations. One variation starts with '1501476 COPR. IBM 1981' and the other, '1501476 COPR. IBM 1982'. There are no functional differences between the two variations. The 10/27/82 image above is of the latter variation.

Options for EPROM type

The BIOS chip in the IBM 5150 has a specific pinout which is not the same as any 27xxx series EPROM.
As detailed at here, replacement options are:

• A MCM68764 or MCM68766 EPROM; or
• A 2564 EPROM; or
• Using a suitable adapter, a 27xxx series EPROM; or
• Using a suitable adapter, a Winbond W27E257 EEPROM.

Use ROM's rated at 250 ns (or faster).

Images (content) for EPROM type

Type of EPROM	Size	Use
MCM68764/MCM68766 EPROM	8K	For content, use one of the above 8 KB sized images.
2564 EPROM	8K	For content, use one of the above 8 KB sized images.
With adapter, 2764/27C64 EPROM	8K	For content, use one of the above 8 KB sized images.
With adapter, 27128/27C128 EPROM	16K	For content, use one of the above 8 KB sized images that has been doubled - see here
With adapter, 27256/27C256 EPROM	32K	For content, use one of the above 8 KB sized images that has been quadrupled - see here
With adapter, W27E257 EEPROM	32K	For content, use one of the above 8 KB sized images that has been quadrupled - see here

5155 (IBM Portable PC)

The 5155 contains an early version of the 5160 motherboard, one that has the 11/08/82 BIOS.

IBM 5160 (IBM XT)

The BIOS (together with BASIC) is contained in chips U18 and U19.

Image of 08/16/82 revision <----- May not have been publicly released. See here.
Image of 11/08/82 revision
Image of 01/10/86 revision
Image of 05/09/86 revision

The 11/08/82 revision of BIOS has two known variations: The copyright string in one variation of the 1501512 ROM is '1501512 COPR. IBM 1981' and in the other, '1501512 COPR. IBM 1982'. There are no functional differences between the two variations. The 11/08/82 image above is of the 1981 variation.

ROM's can be created by programming 27256 EPROM's or 27C256 EPROM's, ones rated at 250 ns (or faster). If you have an early version of the 5160 motherboard, then note the issue described at here.

EEPROM use is possble - see here.

IBM 5162 (IBM XT Model 286)

The BIOS (together with BASIC) is contained in chips U34 and U35.
There was only one BIOS released (21APR86).

Image of 04/21/86 revision

ROM's can be created by programming 27256 EPROM's or 27C256 EPROM's, ones rated at 150 ns (or faster).

EEPROM use is possble - see here.

IBM 5170  (IBM AT)

In very early versions of the IBM 5170, the BIOS (together with BASIC) is in four 16 KB sized chips (of type 27128), in sockets U17/U27/U37/U47.
Later, two 32 KB sized BIOS ROM chips (of type 27256) were supplied instead, one in socket U27 and the other in socket U47.

There were three revisions of the BIOS.

In the final revision, 15NOV85, there are two known variations. They have different part numbers and an inspection of the contents shows that they are functionally the same - only the embedded part number strings differ (and checksum byte). The differing part numbers may be due to the fact that one variation is supplied as PROM's whereas the other is supplied as EPROM's.

Revision 01/10/84 - Type 1 motherboard - Four 27128/27C128
Revision 01/10/84 - Type 1 motherboard - Two 27256/27C256

Revision 06/10/85 - Type 2 motherboard - Two 27256/27C256

Revision 11/15/85 - Type 3 motherboard - Two 27256/27C256 - Variation 1
Revision 11/15/85 - Type 3 motherboard - Two 27256/27C256 - Variation 2

ROM's can be created by programming 27256 EPROM's or 27C256 EPROM's (or equivalent), ones rated at an appropriate speed (see here).

AN AWARD BIOS SUITABLE FOR THE 5170

This generic 286 'IBM compatible' BIOS made by Award was found in a type 1 motherboard.
• Dated 20OCT87 (although it reports 15NOV85, which is the same date as IBM's third BIOS release for the 5170)
• Will no doubt run in all 5170s
• Built-in BIOS setup ("CMOS setup") functionality:
     - CTL-ALT-ESC at start-up will take you into the BIOS setup
     - Defines 40 different hard drive types, and does not have a user defined hard drive type

• Within the BIOS code is:

     IBM COMPATIBLE 286 BIOS
     COPYRIGHT Award Software Inc. 10/20/87
     286 Modular BIOS Version 3.03GS

AWARD release 3.03GS

AN AMI BIOS SUITABLE FOR THE 5170

• Dated 30MAR89
• Will no doubt run in all 5170s
• Built-in BIOS setup ("CMOS setup") functionality:
     - User defined hard drive type (type 47)
     - Diagnostics (includes hard disk format)

• On startup, the following is seen at the top of the screen: 286-BIOS (c)1989 American Megatrends Inc
   On startup, the following is seen at the bottom of the screen: D286-1277-043089-K0

AMI release D286-1277-043089-K0

A QUADTEL BIOS SUITABLE FOR THE 5170

This BIOS was found in a type 3 motherboard, by member Erwin-c64 of the VCFF

In the IBM 5170, the 'speed change' functionality of this BIOS does not work, indicating that the BIOS was intended for other motherboards. But apart from that, all other functionality should work when this BIOS is fitted to a 5170.

• Dated 30MAR90
• Will no doubt run in all 5170s
• Built-in BIOS setup ("CMOS setup") functionality:
     - CTL-ALT-S at start-up will take you into the BIOS setup
     - User defined hard drive type (like type 47)
     - Fast boot, auto-park HDD, screen saver, system password, hard disk format
     - The 2010 year limit can be compensated for by the procedure at here

• On startup, the following is seen at the top of the screen:

     Quadtel Enhanced 286 BIOS Version 3.05.01
     Copyright 1987-1990 Quadtel Corp. All Rights Reserved.
     press "Ctrl-Alt S"     for SETUP
              "Ctrl-Alt +/-" for SPEED CHANGE

Quadtel Enhanced 286 BIOS Version 3.05.01

A PHOENIX BIOS SUITABLE FOR THE 5170

This BIOS was found in an IBM 5170 motherboard, by member Challenger74 of the VCFF

• Dated 19APR90
• Will no doubt run in all 5170s
• Built-in BIOS setup ("CMOS setup") functionality:
     - User defined hard drive type (named 'Custom')
     - System password
     - Boot sequence
     - Swap floppy drives

• On startup, the following is seen at the top of the screen:

     PhoenixBIOS(TM) A286 Version 1.01
     Copyright (C) 1985-1992 Phoenix Technologies Ltd
     All Rights Reserved

     Copyright (C) 1992 Micro Firmware Incorporated
     All Rights Reserved

PhoenixBIOS A286 - Version 1.01