Highlights of the MICROLINE® 420 and Wide-Carriage MICROLINE 421:
- 3-Year standard warranty
- Print speeds up to 570 cps 1
- Integrated USB and IEEE Parallel connectivity standard
- Optional OkiLAN® 6120i 10/100 Base-T Ethernet® internal print server
- Crisp, clear printing on 6-part forms
- Expandable head gap – accommodates multi-part forms and cut-sheet stock including labels and stiff index stock
- 128 KB receive buffer / memory
- 4 million-character ribbon life
- 200-million character printhead life
- Small footprint – ideal for retail countertops
- Uses the same accessories as ML320/321 Turbo Series (excluding ribbons)
Doing the job day after day.
The OKI® MICROLINE® 420 9-pin printer and its wide-carriage counterpart ML421 are a quantum leap forward in Impact printer performance. Engineered for dedicated forms printing in the most demanding point-of-sale, automa-tion and utility environments, ML420/421 printers are right at home in applications such as retail sales counters, medical facilities, automotive rental and repair shops, airline counters, financial departments and manufacturing sites. Their print speed and versatile paper handling make them ideal for the office, too.
Performance is built in.
The ML420/421 sport features that give them a strong edge over their predecessors as well as the competition:
- 3-piece top cover provides easy access and unsurpassed break resistance
- An internal cooling fan provides continuous airflow for the printhead—maximizing throughput productivity for long, unattended print jobs
- Additional feed rollers provide precise forms handling and printed-character placement accuracy
Exceptional paper-handling versatility.
The ML420/421 have a zero-tear feature that accurately positions continuous forms for a clean tear at the perforation, which eliminates wasted stock. You also get perfect results with single sheets, index stock, labels and envelopes, too. All with-out jams or smears.
Value that goes the distance.
The OKI ML420/421 deliver the kind of productivity usually reserved for printers many times the price—starting with a super-fast print speed of 570 characters-per-second (in SuperSpeed Draft mode). Then there’s the rugged printhead—with its 200-million character life, powerful samarium cobalt magnets and stored-energy pins— delivering precise, sharp characters all the way through to the last page of a 6-part form. And the patented OKI closed-loop feedback system that assures character placement accuracy...
The OKI ML420/421: Just turn ‘em on and turn ‘em loose
Built to last, inside and out.
Field-proven reliability is just one reason OKI® MICROLINE® impact printers are the most widely-used in North America.1
The performance-optimized power supply of the ML420/421 has been enlarged to easily handle harsh printing conditions— and its energy management capabilities match power expenditures to print-job size, maximizing the life of the 9-pin printhead and other components. A long-lasting rack-and-pinion drive system ensures print quality longer than belt or cable systems. And the ergonomically-designed, impact-resistant chassis protects the ML420/421 from damage, even in the toughest working environments.
Performance that’s user-friendly. Controls are conveniently placed on the front panel for fast access. The automatic loading of continuous and cut stock makes every print job easier, and the design of the internal sheet separator enables easy loading of tractor-fed paper into the rear push tractor.
OKI has a reputation for quality and reliability no competing printer can claim—and backs it with 3 years of warranty coverage 2 and a network of authorized OKI Dealer Service Centers and Service Depots.
The reliable, affordable ML420/421 can work wonders in virtually any forms-handling application.
1 2002 NPD Intellect and Evans Research Market Share Data.
2 3-year standard warranty parts and labor/2-year printhead.
All specifications subject to change without notice.
Print Speed And Quality

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| Super Speed Draft (cps) |
570 |
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| High Speed Draft |
510 cps (10 cpi) |
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| Utility Speed |
380 cps (10 cpi) |
|
| Near Letter Quality Speed |
95 cps (10 cpi) |
|
| Number Of Colors |
1 |
|
| Maximum Graphics Resolution (dpi) |
240(H) x 216(V) |
|
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Fonts And Bar Codes

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| |
 |
Emulations

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| |
| Oki Data Microline Emulation |
Standard |
|
| IBM Graphics ProPrinter Emulation |
Standard |
|
| Epson FXLQ Series Emulation |
Standard |
|
 |
Paper Handling

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| |
| Number Of Copies (part) |
6 |
|
| Top Pull Tractors |
Optional |
|
| Push Tractors |
Optional |
|
| Paper Feed Rate |
4.5 ips (11.4 cm/sec.) |
|
| Cut Sheet Feeder Option |
Optional |
|
| Roll Paper Stand Option |
Optional |
|
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Connectivity

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| |
| Number of Pins |
9 |
|
| Parallel Interface |
Standard |
|
| Serial Interface |
Optional |
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| USB |
Yes |
|
| Network Capability |
No |
|
 |
Printhead

|
| |
| Printhead Life (Characters) |
200 million characters |
|
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Performance

|
| |
| Memory Buffer Size |
128K |
|
| MTBF @ 25% of Duty Cycle (in hours) |
20000 |
|
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Operating / Physical Specifications

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| |
| Noise Level In Operating Mode |
56 dBA |
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| Ribbon Life (Characters) |
4 million characters |
|
| Dimensions Of Wide Carriage Without Box (W x D x H) |
21.7" x 13.6" x 6.0" (55.1 cm x 34.5 cm x 15.2 cm) |