Thunderscan: a Clever Device Transforms a Printer Into a Scanner (2004)
Posted3 months agoActive3 months ago
folklore.orgTechstory
excitedpositive
Debate
20/100
Retro TechScanning TechnologyHardware Hacking
Key topics
Retro Tech
Scanning Technology
Hardware Hacking
The Thunderscan was a clever device that turned an Apple ImageWriter printer into a scanner in the 1980s, sparking nostalgia and discussion about its innovative design and the creativity of repurposing old technology.
Snapshot generated from the HN discussion
Discussion Activity
Active discussionFirst comment
1h
Peak period
14
2-4h
Avg / period
4
Comment distribution36 data points
Loading chart...
Based on 36 loaded comments
Key moments
- 01Story posted
Oct 4, 2025 at 8:16 AM EDT
3 months ago
Step 01 - 02First comment
Oct 4, 2025 at 9:43 AM EDT
1h after posting
Step 02 - 03Peak activity
14 comments in 2-4h
Hottest window of the conversation
Step 03 - 04Latest activity
Oct 5, 2025 at 12:35 PM EDT
3 months ago
Step 04
Generating AI Summary...
Analyzing up to 500 comments to identify key contributors and discussion patterns
ID: 45472765Type: storyLast synced: 11/20/2025, 3:47:06 PM
Want the full context?
Jump to the original sources
Read the primary article or dive into the live Hacker News thread when you're ready.
A little later, the LaserWriter printer became the first generally affordable laser printer. But it was affordable only if you were rich or had a business case for it. The sub-thousand dollar laser printer took quite a few more years.
It was probably easier to come by in 1987. Nowadays if you have a unique idea in computing, there’s 40 years’ worth of computing professionals around to step in and take the job.
I'm lucky enough to own two working ThunderScans now (and one third one that I needed the software driver from). They work exactly as advertised, and it's a joy to see them zip across the page, digitising line by line.
The software by Hertzfeld is another joy to use. The scrolling, which Hertzfeld calls "inertial scrolling" in that article, is now familiar to us all who have used touchscreen devices. It's funny to think that the feature that wowed so many at the 2007 iPhone launch actually existed all the way back in 1984, designed by one of the key creators of the Macintosh.
I wish there were more creative hacks like this - I just know that if a company tried to do something similar today, the printer manufacturer would instantly roll out an update to break this functionality.
The entire device consists of a single, cheap CMOS image sensor, a lens focused at a fixed distance and a RGB led. Everything else, stitching the resulting scanbands, correcting for mechanical and optical distortions, etc. is all in software. The native optical resolution you could expect from, say, a 1080x720 px sensor would be something like 2400 DPI.
The only downside i can think is that you can't scan IDs, passports etc. and the location near the inkjet head tends to get dirty.
I think also it was expensive, since I wanted to get it, but failed to find it.
OTOH, a 10 year old HP multifunction can scan things at 600DPI in acceptable quality and detail, in a very reasonable amount of time.
If you want to go compact, but fast, there's Kodak Alaris' "i" series scanners which can scan both sides at the same time. Scan time is ~4 seconds per double sided A5 page at 600DPI, and less than a second for ~200 DPI.
That thing zips, but is not cheap.
Of course taking a picture with the phone requires good lighting and the photos you want to scan need to be flat.
It worked, but there was a clear linear pattern across scans. It worked for some things, but wasn’t the best for photos.
For example, my Epson inkjet printer can do about 10ppm at it's lowest print quality, so it can mechanically move and scan a page against the printhead every 6 seconds; a 1Mpx sensor with a 60Hz frame rate will generate 360Mpx in 6 seconds. Even if you throw away 50% of the data (overlap areas, next page load, motion or optical blur at the edges etc.), that's still enough data for a ~1400 dpi raw resolution of an A4 page at the fastest speed. If you are willing to go slower, the resolutions the system could achieve seem outside the range of any flatbed.
Of course, you would need e very beefy image processor to handle the multiple Gbps raw video data and process in real time down to the final scan image, but the actual corrections seem very achievable with modern algorithms.
Outside of the cost of the image processor, another showstopper I can see is motion blur on the sensor, stopping the heavy printhead from its inertia, so that you can have a still image, will kill your total scan speed. But perhaps you can just pulse the LED, or a gas discharge lamp, and impress the sensor with near instantaneous flashes of light.
It's a fantastic ideal for nerds who like to repair and upgrade and Frankenstein tech bits into new shapes, but I'm not sure I've ever met a normal person who was interested in adding a feature to an existing widget instead of buying a new widget.
I'm absolutely certain this is because it's less profitable for businesses to offer upgradable or interoperable parts.
I feel like MacDraw (or some other lesser-known app — not MacPaint) exposed this functionality.
After he left and after the store owner stopped laughing, she explained that I’d been trying to sell Robin Williams on the basis of price. I like to think he enjoyed being treated like a guy off the street.
I just found his autograph while cleaning last night.. now after seeing this comment, I'm going to give him a call tomorrow :)
Early on I used it to make a picture of Madonna with a fish stuck through her head.
While the Canon may be the first color-capable unit, it's interesting to see it wasn't the first ever!
There is a nice reverse engineering of the Thunderscan here: https://beefchicken.com/retro/thunderscan/
Was that a feature of the software? Or did the person scanning add it to brag about their rig, I wonder.