# Packet 0x90
PSOv1 clients send this packet to log onto the login server. The server should then respond with its own Packet 0x90 indicating a response to the login.
## Dreamcast Packet Format (Client->Server)
| Bytes | Meaning |
| --- | --- |
| 0x00 | Packet Type (0x90) |
| 0x01 | Flags (0x00) |
| 0x02-0x03 | Packet Size (0x0028) |
| 0x04-0x0B | Serial Number |
| 0x0C-0x14 | Unused |
| 0x15-0x1C | Access Key |
| 0x1D-0x27 | Unused |
## Dreamcast Packet Format (Server->Client)
| Bytes | Meaning |
| --- | --- |
| 0x00 | Packet Type (0x90) |
| 0x01 | Flags (Login Response) |
| 0x02-0x03 | Packet Size (0x0004) |
### Login Responses
| Flag | Meaning |
| --- | --- |
| 0 | Login Ok (Client sends a [Packet 0x93](server-protocol/Packet_0x93) next) |
| 1 | New user (Client sends a [Packet 0x92](server-protocol/Packet_0x92) next) |
| 2 | Login Ok (Client sends a [Packet 0x93](server-protocol/Packet_0x93) next) |
| 3 | Invalid Serial Number and/or Access Key (Client disconnects) |
