PC-98

PC-98

Developed by: NEC Published by: NEC First Released: October 1982 This software has developer-related easter eggs.

The NEC PC-9801 series of computers (also known as the PC-9821 for the 256 color models, as a "Touhou machine", or simply PC-98) was a popular series of Japanese computer that was manufactured and sold from 1982 to 2003. While initially it was a boring Japanese business computer, sound cards and improved graphics hardware in the VM and VX turned the PC-9801 into a popular gaming platform for visual novels/adventure games, ports of western PC games, and doujin games. While the PC-98 had numerous games that were backwards and forwards compatible with older and newer machines, Windows 3.1 and later 95 killed off the demand for the PC-98 platform and allowed the PC-98 (and FM Towns) to run the same software a normal PC could.

PC-9800 BIOS TEAM Credits

The ITF ROM of the PC-98 contains the setup menu and some diagnostics depending on the model. At offset 7F00, a NEC copyright string can be found. On some ITF ROMs this is followed with credits of who worked on the machine. This features characters doubled on each ROM as the PC-98 used an odd/even interleaving structure for boot ROMs. One such ROM from the PC-98RL has these credits:

CCOOPPYYRRIIGGHHTT  ((CC))  NNEECC  CCOORRPPOORRAATTIIOONN  11998822,,11998899  
DON HASHIBA$
ITF BANBA$
FD  KANAI$
SASI SATO$
SCSI/PRN TSURUMI$
KB/TIMER/CAL/CRT TACHIBANA$
RS NAGATOMO$
  PC-9800 SERIES BIOS TEAM

While a later PC-9821 boot ROM with the checksum of DD4C7BB8 (from MAME) has different names:

COPYRIGHT (C) NEC CORPORATION  1982,1994 
DON UENAKA$
ITF/MENU SAKU&YAMA$
FD/HD/PRN SUZUKI$
GRAPH MORI$
KB/CRT/RS/CLK/TIM TAKEMORI$
SYS KANEKO$
PC-9800 SERIES BIOS TEAM

Additionally, the PC-9821Ra43 has this at 0x3FF24H:

COPYRIGHT (C) NEC CORPORATION  1982,2000 
Thank you for using PC9800 series for a long time$
DON UENAKA$
ITF/MENU SAKU&YAMA&AMA$
SYSTEM TAKEMORI$
PC-9800 SERIES BIOS TEAM

(Source: CanadaPost (first two messages))

(Source: FlyingHaruka (Ra43 message))

The anti-Epson check

Seiko Epson (yes, the company that makes printers) is a Japanese computer manufacturer who cloned the NEC PC-98 series of computers for a while. There was a legal battle between NEC and Epson and after it was settled, NEC's versions of MS-DOS began to check for a copyright string before the OS would boot. Effectively this locked NEC distributed versions of MS-DOS to NEC hardware. This string can be found at location E800:0DD8 on NEC PC-98 machines.

Copyright (C) 1983 by NEC Corporation / Microsoft Corp.

This has to be done to properly boot these operating systems in emulators as well, and DOSBox-X has a bug talking about this very issue. This was not a problem with Epson's versions of DOS as they lacked this check, and MS-DOS 6.2 removed the check.