IBM TDB - Conversion Connector for the IBM Personal Computer [clone floppy on PS/2]

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Louis Ohland

Oct 17, 2021, 12:55:52 PMOct 17
Image is poor quality, but I'd bet it can be figured out.

Conversion Connector for the IBM Personal Computer Described is a
hardware implementation to enable industry standard diskette drive edge
connectors to connect to the IBM Personal Computer (PC) and IBM PS/2*
diskette drive cable connectors.

Fig. 1 shows the interface conversion circuitry required to enable the
2X17 card edge connector to be wired to the industry standard Berg
connector. Fig. 2 shows the wiring designation for the thirty-four pins
of the IBM connector and the Berg connector.

With this interconnection, the printed circuit card with the appropriate
connectors and circuits will allow the signal conversion and connection
of an IBM PC flat ribbon cable for floppy disk drives to connect to any
industry standard card edge Input/Output (I/O) connector, as required
for diskette drives.

Oct 17, 2021, 6:08:38 PMOct 17
On Sun, 17 Oct 2021 11:54:56 -0500, Louis Ohland <>
How do they deal with the pin 2 problem? Industry drives have a media
switch that sends a signal to the controller. IBM drives have no
switch and the media type is selected by the software/controller.
(Prior to the second generation PS/2s)
Basically you can put any media in an IBM drive and format it any way
you like. The controller has no clue what you are feeding it. On
reading a written disk it looks at the media descriptor byte in the
boot sector.
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