Date   : Thu, 04 Nov 2010 03:12:35 +0100
From   : rick@... (Rick Murray)
Subject: Acorn's US patent

I was looking through a patent repository to see if I could find any 
info on the scantly-documented Psion link as used in the series 3(a) and 
the PocketBook (II) versions.

I did track down something, at:
   http://www.freepatentsonline.com/5247657.pdf

I then tried looking for the company and I noticed there's a patent even 
for the design of the RAM/ROM/Flash casing, but oddly none for the S3(a) 
itself, though there is for the series 5 casing.

Anyway, I then tried looking under "Acorn Computers" as an assignee, and 
found two, one of which is:
   http://www.freepatentsonline.com/5497434.pdf


Though as I am reading this, I have a mental hiccup on:

    The rate at which data can be read from a CD-ROM is limited to about
    150,000 bytes per second which allows about 6000 bytes for each
    frame at a frame rate of 25 frames per second. This is reduced to
    about 500 bytes per frame when provision is made recording sound to
    accompany the moving images and to allow for access latency in the
    storage device. Compressing an image of an acceptable quality to
    5000 bytes per frame requires the use of sophisticated compression
    and decompression algorithms which in turn place high demands upon
    the processing capacity of the computer system.

Did you spot it too? When you add in sound to the CD-ROM data speed, it 
leaves you a paltry five HUNDRED bytes per frame.

The other patent is:
   http://www.freepatentsonline.com/5400044.pdf
which describes a method of taking a one bpp LCD display (pixel on or 
pixel off) and modulating pixels around plus refresh speeds, to make a 
pseudo-greyscale display device out of it.

I've done a rudimentary (time based only) version of this in tests with 
my Psion 3A in order to simulate around 7 or 8 shades with the 
whitish-grey-black display; though I'm not sure the hardware is up to 
greyscale bitmaps except by using dithering. It was, I should point out, 
nastily blinky in direct light.


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...