Special boot-up key commands [NEC PC98]
Hold down a key showed in bellow table when you turn on the machine or reset it. Ten keys (numeric pad) doesn't work.
| Key | Function | Notes |
|---|---|---|
| STOP | Skip system memory test | Undocumented |
| TAB | Show Fixed Disk Boot menu | With an extended formatted HD. |
| COPY | Boot from RAM drive | Only laptop models with a RAM hard drive |
| SHIFT+STOP+CTRL | Dump system memory into FD | PC-9801VX and later, undocumented |
| CTRL+CAPS+カナ+GRPH | Show CPU speed and screen mode | PC-9801RA and later, undocumented |
| CTRL+SHIFT | Reset data in Memory switch | Only laptop models, undocumented |
| GRPH+SHIFT | Reset data in Memory switch | PC-9801DA and later, undocumented |
| HELP | Access to System Setup Menu | PC-9801DA and later |
| HELP+RETURN | Access to System Setup Menu | Some machines come with CPU upgrade kit |
| GRPH+1 | Set H-Freq of monitor-out to 24 kHz | PC-9821 and later except model S1, S2 |
| GRPH+2 | Set H-Freq of monitor-out to 31 kHz | PC-9821 and later except model S1, S2 |
| HELP+ESC+1 | Show BIOS revision | PC-9821An and later, undocumented |
| HELP+ESC+5 | Allow sending memory refresh to C-bus | PC-9821 and later, undocumented |
| HELP+ESC+6 | Stop sending memory refresh to C-bus | PC-9821 and later, undocumented |
| HELP+ESC+8 | Show BIOS Update Menu | PC-9821 and later, undocumented |
| HELP+ESC+9 | Init PnP (Plug and Play) BIOS | PnP supported models, undocumented |
| CTRL | Boot from FD | in High Resolution mode (only specific models) |
| ESC | Boot from drive number 00 | in High Resolution mode (only specific models) |
| f1 - vf5 | Boot from its drive number | in High Resolution mode (only specific models) |
Source: 第三研究所 第一電算機研究室 NEC PC-9800シリーズ、SV-98シリーズ裏コマンド一覧表 http://www.amy.hi-ho.ne.jp/nakajima-jr/com/appendix/uracom.htm