| Carriage | Wide |
| Connector/Port/Interface | Parallel, USB |
| Depth | 13.6 in |
| Emulations | Epson® ESC/P2, IBM® AGM, IBM® PPR |
| Global Product Type | Printers-Dot Matrix |
| Height | 4.6 in |
| High Speed Draft Printing | 390.0 cps |
| Input Buffer | 23 kB |
| LCD Display | No |
| Maximum Form Parts | 4 |
| Maximum Print Speed (Black) | 390.0 cps |
| Model Name/Number | Microline® 391 |
| Monthly Duty Cycle (Pages) | 12000 |
| Near Letter-Quality Printing Speed | 105.0 cps |
| Network Capable | Yes |
| Network Ready | No |
| Number of Pins | 24 |
| Operating System Compatibility | Novell NetWare®, UNIX®, Windows® 3.1, 3.11, 3.51, 95, NT 4.0 |
| Paper Feeder Type | Sheet Tray |
| PC Free Printing | No |
| Print Resolution (Black) (Width x Height) | 360 x 360 dpi |
| Printer Type | Dot Matrix |
| Standard Memory | 64.0 kB |
| Utility Printing Speed | 315.0 cps |
| Width | 21.70 in |