modem7
10k Member
According to:
1. Microsoft article 33706
2. Various editions of Upgrading & Repairing PC's (Scott Mueller)
3. Internet sources
4. ROMs in possession
5. Information provided by members of these forums
-------------------------
04/24/81
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 5700051
ID/SUBMODEL/VERSION = FF/--/--
* Used on 16/64K motherboards.
* Only up to 544K RAM is recognisable (BIOS only reads first 4 switches of the SW2 block)
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
-------------------------
10/19/81
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 5700671
ID/SUBMODEL/VERSION = FF/--/--
* Fixed a couple of minor display bugs.
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
-------------------------
10/27/82
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 1501476
ID/SUBMODEL/VERSION = FF/--/--
* All 64/256K motherboards contained the 10/27/82 BIOS.
* 640K RAM is now recognisable (BIOS now reads first 5 switches of the SW2 block)
* All machines released after Mar'83 have this version of the BIOS.
* In Apr'84, IBM released a 'BIOS Update kit' for the 16/64K motherboards to update the BIOS to this version.
* Adds support for adapters that have a ROM BIOS extension (e.g. hard disk drive adapter)
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
1. Microsoft article 33706
2. Various editions of Upgrading & Repairing PC's (Scott Mueller)
3. Internet sources
4. ROMs in possession
5. Information provided by members of these forums
-------------------------
04/24/81
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 5700051
ID/SUBMODEL/VERSION = FF/--/--
* Used on 16/64K motherboards.
* Only up to 544K RAM is recognisable (BIOS only reads first 4 switches of the SW2 block)
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
-------------------------
10/19/81
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 5700671
ID/SUBMODEL/VERSION = FF/--/--
* Fixed a couple of minor display bugs.
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
-------------------------
10/27/82
-------------------------
ROM SIZE = 40K (U33 BIOS = 8K, U29-U32 BASIC = 8K each)
ROM U33 = 8K chip labeled with IBM part number of 1501476
ID/SUBMODEL/VERSION = FF/--/--
* All 64/256K motherboards contained the 10/27/82 BIOS.
* 640K RAM is now recognisable (BIOS now reads first 5 switches of the SW2 block)
* All machines released after Mar'83 have this version of the BIOS.
* In Apr'84, IBM released a 'BIOS Update kit' for the 16/64K motherboards to update the BIOS to this version.
* Adds support for adapters that have a ROM BIOS extension (e.g. hard disk drive adapter)
Memory map:
. = unused
b = ROM BASIC
R = ROM BIOS
------: 0---1---2---3---4---5---6---7---8---9---A---B---C---D---E---F---
0F0000: ........................bbbbbbbbbbbbbbbbbbbbbbbbbb bbbbbbRRRRRRRR
------: ........................|<-U29->|<-U30->|<-U31->|<-U32->|<-U33->|
Last edited: