One sub page is devoted to the history of the HP200A and has quite a bit of information I have not seen anywhere else. The page was posted in Jan. 2002 which was the 60^th anniversary year of the patent William Hewlett received for the audio oscillator in 1942.  This particular oscillator is supposedly the first one Bill assembled for his master's thesis at Stanford.  That unit would have been for demonstration and not for production.  There are several interesting things to note about it:

• The variable capacitor has a right angle drive.  That was not the case for the production 200A, B, C, and D units -- they were straight shaft only. 
  
• There are only four vacuum tubes.  The production versions had five tubes.  However, what is identified as the light bulb may be a tube instead.  The picture has too low resolution to be sure.
  
• There is only a power transformer.  There is no audio output transformer as was on production units.  This might be consistent with only four tubes with only one tube used for the output amplifier.
  
• Although the 1939 schematic shown on the page has such low resolution that it is nearly impossible to read but I can make out that there are five tubes and an audio output transformer shown.  But that is a later version of the original thesis unit.
  
• The tuning dial shown appears to be from a production 200B unit.
  
• The red and black output jacks are not the originals -- those would have probably been lost/worn over the years and would have been replaced.

Agilent Technologies and Communications: Six Decades of Measurement Solutions This is an excellent 35 page article about many of the classic pieces of equipment developed at HP. It has a lot of history and is required reading. There are a few errors that should be noted as follows. I was not looking for errors but these stood out to me as I am familiar with these.

1. The opening picture showing David Packard (standing) and William Hewlett (with slide rule) in the garage is mirror imaged. Proof that the picture is mirrored is obvious by looking at the audio oscillators and noting that the output jacks appear on the left instead of their correct place on the right. The same picture on the HP site above is correct.
   
2. On page 18 the upper frequency limit of the HP500A frequency meter should be 50 kHz instead of 100 kHz. I own an HP500A and am quite familiar with it.
   
3. On page 20 the model number of the VHF generator in the picture should be HP8640B. This is a simple transposition error in the caption. I own one of these units so I am quite familiar with it.
   
4. On page 22 the year HP entered the oscilloscope market should be 1956 instead of 1958 (product development actually began in 1955). The March, 1956 (Volume 7, #7) issue of the Hewlett-Packard Journal describes the introduction of the HP130A oscilloscope which had a 300 kHz bandwidth. The April, 1956 (Volume 7, #8) issue of the Hewlett-Packard Journal describes the introduction of the HP150A oscilloscope which had a 10 MHz bandwidth.
   
5. On page 28 the description of the HP4815A impedance meter should show an upper frequency limit of 108 MHz instead of 500 MHz. I own an HP4815A and am quite familiar with it.