86-DOS 0.33

86-DOS 0.33 is a released beta build of QDOS/86-DOS. It was shipped with 2 manuals: the 86-DOS Version 0.3 Programmer's Manual and the 86-DOS Version 0.3 User's Manual.

The version number for this build is mentioned in David Hunter's 1983 interview with Tim Paterson, published in Softalk for the IBM PC. Paterson noted the lack of variable sector record sizes in this version and ones before it. The feature would be added in 86-DOS 0.42.

New features
86-DOS 0.33 doesn't change much to 86-DOS 0.2. Most changes occur internally. However, an early form of the  command was added; additionally, interrupts and function calls were majorly reworked for developers.

DEBUG
DEBUG is 86-DOS' resident debugger. It would later be modified and used by IBM in its PC-DOS, as well as by Microsoft in MS-DOS, and gain some preliminary disassembly powers.

History
DEBUG was originally developed in January 1979 to aid in 8086 software development. It was originally on a ROM chip alongside Seattle Computer Products' 8086 monitor, but would later be converted to a .COM file and added to the operating system.

DEBUG has been compared to CP/M's Dynamic Debugging Tool (DDT) by critics. However, other reviewers have called it "as good as any of the general-purpose debuggers to be found in the 8-bit world" and noted its good instruction tracing compared to Z80 debuggers like DDT or ZSID.

Usage
The command  loads a binary (.COM) file to address 0100h in memory and allows a user to enter commands. The commands are as follows:

Commands
The following list includes only newly confirmed commands, and not the ones already known to be present in 86-DOS 0.2 and QDOS 0.10. They are all sourced from the user's and programmer's manuals.

Barry Watzman disk
comp.os.cpm newgroup member Barry Watzman (May 26, 1949 – May 17, 2010) owned and subsequently sold five Seattle Computer Products floppy disks, including an 86-DOS 0.33 disk. Watzman bought the 8-inch diskette directly from Seattle Computer products due to an ad in BYTE Magazine. Along with the operating system and the manuals that came with it, he also bought SCP's S-100 system, including the hardware used inside the Gazelle and the Tarbell double-density disk controller.