PCjs Machines

Home of the original IBM PC emulator for browsers.


IBM PC (Model 5150) ROMs

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.

As hinted above, some newer Model 5150 machines with the Oct 27, 1982 BIOS included IBM BASIC C1.10. And some even newer 5150 machines had a BIOS with a “1982” copyright year instead of “1981”, which also changed the checksum byte from 0x78 to 0x77. However, the project includes only the original “1981” version, since the difference is trivial.

Source Code

PCjs has created and archived a collection IBM PC ROM BIOS diskettes. Their contents are thanks to the PC DOS Retro website.