board scan, design reconstruction (was IMSAI)

Randy Dawson rdawson16 at
Wed Feb 27 13:20:06 CST 2008

> Date: Wed, 27 Feb 2008 09:48:10 -0900
> From: grant at
> To: cctech at
> Subject: Re: TTL CPU Re: IMSAI style C&K 7101 switches
> At 06:40 AM 2/26/2008, you wrote:
> >Grant,
> >
> > > On a side note, who here would be interested in ultra high resolution
> > > scans of old computer PCBs?  I'm scanning all PCBs at 3200dpi for
> > > archival.  Photoshop won't save jpegs that large, but a 1600dpi scan is
> > > only 50MB or so.  Some day I plan to release my whole archive.
> >
> >You mentioned JPEGs.  If you are archiving the scans in JPEG format,
> >try zooming in on bunches of traces or text on the board.  JPEG creates
> >a lot of artifacts.
> >
> >It may very well be case that a 600dpi scan using lossless compression
> >will be much cleaner and usable than a 3200dpi scan using heavy JPEG
> >compression.
> >
> >Even with 6 mil traces, 600dpi gives you more than 3 pixels per trace.
> >
> >I've tried a few of my boards using 1200dpi, 8-bit color, and GIF/TIFF,
> >with results that seemed acceptable.
> I scan all of my boards at 3200dpi 48bit color in TIFF format.  I'm 
> not going to upload any 3.5GB images (one for each side of an S-100 
> card).  If you mail me a hard drive I will be happy to copy them.  : 
> )  Its faster to rescan them at 1600dpi 24bit than it is to open and 
> resave them.
> Color scans are needed if you want to have a PCB shop make gerbers 
> out of your scan.
> Grant 

Ive been following this, and maybe I can help.  Im a professional PCB layout guy in my day job.  With a schematic and a reasonable resolution jpeg of both sides (I doubt there was mych multylayer back then) I could reconstruct the design fairly quickly.  Nobody is really going to want to go down the road of taking a picture and turning it into a gerber, it just wont work.  Id just input the schematic, duplicate the ref des for all parts, to get the netlist, eyeball the jpeg for placement and throw it at the autorouter.

Whats on your top 10 list?


CPU card
Byte Blaster
Async card
disk controller card

I could knock those out in a week or two.


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