BASIC-DOS is still in development. The target release date is August 12, 2021.
This is a preview of an unfinished product.
This is a “sneak peek” at BASIC-DOS, the first version of DOS that could have been created for the IBM PC, with the benefit of more time and incredible foresight.
The machine shown below is an IBM PC (Model 5150) with two floppy disk drives and a Color Graphics Adapter (CGA) connected to a Color Monitor. The machine was originally configured with 64K of RAM, but it has been upgraded to 128K for this preview.
A BASIC-DOS boot diskette (BASIC-DOS1) has been loaded into drive A:. The
boot sector loads IBMBIO.COM into memory, which in turn loads CONFIG.SYS
and IBMDOS.COM. Like PC DOS, IBMBIO contains all the BASIC-DOS
device drivers and IBMDOS contains all the Disk Operating System services.
Finally, IBMDOS loads COMMAND.COM into memory, which provides the initial
A> command prompt.
All files are original BASIC-DOS production and test files, with the exception of SYMDEB (Microsoft’s Symbolic Debug Utility v4.00) and MSBASIC.EXE, which was built from Microsoft’s GW-BASIC open-source files, with a little help from OS/2 Museum. These two files are used for early testing and debugging only, and they will not be distributed with the finished BASIC-DOS product.
NOTE: All preview binaries shown here are DEBUG versions, which means that all run-time assertions are enabled, so file sizes and memory usage are larger than normal, and overall performance is slightly lower. Even so, BASIC-DOS outperforms PC DOS in several respects. More on that later.
Like PC DOS, BASIC-DOS supports a FAT file system, COM and EXE executable formats, and many of the same PC DOS APIs, commands, and data structures, including Program Segment Prefixes (PSPs) and File Control Blocks (FCBs).
However, compatibility is not the primary goal of BASIC-DOS. The true goal is to demonstrate what could have been achieved as the first IBM PC operating system, not to create a “clone” of PC DOS and endlessly chase compatibility problems. To whatever extent BASIC-DOS is compatible with PC DOS, that compatibility is born purely out of convenience, relying on existing designs whenever it makes sense to do so – just as PC DOS and its predecessors relied on CP/M designs, CP/M relied on DEC designs, and so on.
In some ways, BASIC-DOS is more primitive than PC DOS 1.00. File system functions are read-only (files cannot be created, written, renamed, or deleted), and FCB functionality is limited. However, those are temporary limitations that will be addressed in the coming months.
In other ways, BASIC-DOS leap-frogs PC DOS 1.00, by adding the ability to read PC DOS 2.00-formatted diskettes, load PC DOS 2.00-style device drivers, perform handle-based I/O, support pipe and redirection operations, and last but not least, preemptive multitasking of multiple DOS applications across multiple screens or portions of a single screen.
And, true to its name, BASIC-DOS has begun incorporating BASIC language functionality into the command interpreter. COMMAND.COM is on its way to becoming a unified DOS and BASIC command interpreter.
Copyright (c) 2020-2021 Jeff Parsons Released under MIT License