Obscure Computers: G-15 schematics

This set of documents is schematics. They were orginally with G-15D serial number 186 in Houston, Texas.

1c2100a.gif is the schematic for CF-3, Cathode Follower-3, basically a modification of CF-1 that was done later (probably to tweak the circuit's frequency response to cure a specific timing problem somewhere).

3d640ld.gif and 3d640rd.gif are the left and right halves of Drawing 3D640, Schematic -- Typewriter, change level D. The typewriter itself was manufactured by IBM; the switches SW-1, SW-2, and SW-4, however, were on an add-on unit that sat under the typewriter. These switches are used for certain control functions.

3d643le.gif and 3d643re.gif are the left and right halves of Drawing 3D643, Schematic -- Coupler Matrix, change level E. This is the interface between the typewriter and the computer, for any computer withOUT the alphanumeric option installed.

3d661la.gif and 3d661ra.gif are the left and right halves of Drawing 3D661, Schematic -- Decoder, Alphanumeric Coupler, change level A. This is the interface between the computer and the typewriter for any computer WITH the alphanumeric option installed. It obsoletes 3D646.

pr2ctrl.gif describes the PR2 control, the paper tape reader I believe, which was an OEM item. My guess here is that later G15s had a newer design of paper tape reader, one with transistorized controls. The drawing itself has no part number.

Scanned by Mark Linimon, linimon@lonesome.com, 1/12/2000.