ManiOS DOS compatibility: VisiCalc and Ability Plus
Test date: 2026-10-23
Source commit: 8446024739140e21e9e884e61cf6656f0bb09845
Environment: QEMU i386, CPU 486, 64 MiB, fresh FAT16 snapshot per case
Program observation limit: 12 seconds. All three returned to shell.
Original files unchanged; application binaries and disk images excluded.

CASE: visicalc
CWD: /n/ata0p1/vc
COMMAND: dosrun C:/VC/VC.COM
dosrun C:/VC/VC.COM
dosrun: C:/VC/VC.COM: can't run opcode EC (at 1000:6A3E)

CASE: ability
CWD: /n/ata0p1/ab3
COMMAND: dosrun C:/AB3/AB30.EXE
dosrun C:/AB3/AB30.EXE
dosrun: C:/AB3/AB30.EXE: can't run opcode DB (at 10EA:2582)

CASE: ability-install
CWD: /n/ata0p1/ab3
COMMAND: dosrun C:/AB3/INSTALL.EXE
dosrun C:/AB3/INSTALL.EXE
dosrun: C:/AB3/INSTALL.EXE: can't run opcode 66 (at 1010:165A)

Diagnostic host probes (instruction bytes after the consumed fault opcode):
vc/VC.COM
FAULT opcode EC
CS=1000 IP=6a3e opcode=ec next=a8 01 75 fb DX=03da AX=7043

ab3/AB30.EXE
FAULT opcode DB
CS=10ea IP=2582 opcode=db next=e3 be e0 22 DX=a07c AX=0003

ab3/INSTALL.EXE
FAULT opcode 66
CS=1010 IP=165a opcode=66 next=8b d4 83 e4 DX=10ee AX=f000

Interpretation:
VC.COM: EC = IN AL,DX; DX=03DAh, video input-status register polling. Hardware port I/O is unsupported.
AB30.EXE: DB E3 = FNINIT, x87 initialization. No x87 emulation exists in this runtime. A later NE header and Phar Lap strings are also present; fixing this first instruction alone would not establish compatibility.
INSTALL.EXE: 66 8B D4 = MOV EDX,ESP using an operand-size override; the runtime supports 16-bit operands only.
No usable spreadsheet, integrated-suite or installation workflow was reached.
Input and kernel/source SHA256 hashes are in the companion JSON.
