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: • MCM68766 EPROM; or

The BIOS in this project currently is a modified 5150 V2 BIOS (U33 5700671 19th October 1981). The modifications here should hopefully allow similar modifications to be made to other versions if required. To assemble the BIOS, use the following command. uasm64.exe -0 -bin -Fl PCBIOSV2.asm-0 indicates that we'd like 8086 code to be generated.

On the 5150 motherboard, the ROM in socket U33 contains the BIOS. Note that the ROM's in sockets U29/U30/U31/U32 are not part of the BIOS. Those ROM's contain cassette BASIC .

IBM PC BIOS dated 04/24/81 is 5940 lines based on the BIOS listings in the IBM PC Technical Reference dated August 1981. The BIOS was likely built using the Intel ASM86 Macro Assembler V1.0.

IBM PC (Model 5150) BIOS ROMs include: In general, IBM BASIC ROM images are 32Kb and IBM BIOS ROM images are 8Kb, and together they provide 40Kb of contiguous read-only memory, with the BASIC ROM spanning physical addresses 0xF6000-0xFDFFF and the BIOS ROM spanning addresses 0xFE000-0xFFFFF.

May 29, 2006 · Using Debug commands, I have extracted three IBM PC 5150 BIOS versions. They can be retrieved here: The numbers associated with these files correspond to their IBM 5150 serial numbers. The silkscreen markings on the ROM chips are listed below (slashes separate each line).

Feb 24, 2016 · 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.

MIOS is a chip-for-chip replacement of the BIOS (Basic Input Output System) on the IBM 5150 Personal Computer. On the IBM PC the BIOS is contained in a ROM IC Chip located on the motherboard at socket location U33. The IC is socketed and can be replaced with a custom ROM containing custom code.

IBM 5150 - Substituting the U33 BIOS ROM The BIOS ROM on an IBM 5150 motherboard is located in socket U33. The ROM is an 8 KB sized device, with a specific pinout.

Oct 28, 2017 · The Super PC/Turbo XT BIOS is heavily modified version of the widely-distributed "(c) Anonymous Generic Turbo XT" BIOS. It is a drop-in replacement for the IBM 5150/5155/5160 BIOS and most XT clones, including 8/10 MHz turbo systems.