OKI Microline ML320 Turbo: Setup, Drivers, Ink and Common Problems

Is the OKI Microline ML320 Turbo right for you?

The ML320 Turbo is a 9-pin impact printer that has been in production for decades because nothing else prints multi-part carbonless forms as cheaply. Warehouses, workshops, pharmacies and freight offices still buy them for delivery notes, prescriptions and invoices. Print quality is deliberately utilitarian; what matters is the impact head, which must strike hard enough to mark the bottom copy of a four-part set.

Best for: Warehouses and offices printing multi-part carbonless forms

Setting up the OKI Microline ML320 Turbo

Set the paper-thickness lever to match the number of form parts, since too low a setting smudges and too high gives a faint bottom copy. Emulation matters more than the driver on this machine: choose IBM Proprinter or Epson FX emulation on the front panel to match what your business software expects. On Windows, connect by USB and use the OKI ML320 Turbo driver or a Generic / Text Only driver for line-mode printing from legacy applications.

1. Unbox and prepare. Remove every piece of shipping tape and packing material, install the ink cartridges, and load paper in the tray.
2. Join your Wi-Fi. Keep the printer close to the router for setup. Most printers only connect to the 2.4GHz band, so if your router broadcasts one merged network name you may need to split the bands temporarily. See our Wi-Fi guide if it will not join.
3. Install the setup app. Use OKI's official app rather than a driver you found on a search result — third-party driver sites are the most common source of printer malware.
4. Add the printer. On Windows 11: Settings › Bluetooth & devices › Printers & scanners › Add device. On macOS: System Settings › Printers & Scanners › Add Printer.
5. Print a test page and run a scan if this is an all-in-one, so you find any problem now rather than when you are in a hurry.

Ink, toner and supplies

The OKI Microline ML320 Turbo uses the following consumables. Match the number exactly when you buy: the same printer family often uses several different cartridge numbers by region.

• OKI ML320/321 black ribbon cartridge (approx. 3 million characters)

High-yield (XL) versions almost always cost less per page if you print regularly. On third-party ink and toner, read our honest assessment first, and note that some manufacturers push firmware that rejects non-original chips.

Full specifications