Browse Prior Art Database

Bus Expansion for Chip Card

IP.com Disclosure Number: IPCOM000118513D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 78K

Publishing Venue

IBM

Related People

Sakanaka, J: AUTHOR

Abstract

ChipCard is a device in the form factor of Personal Computer (PC) card, which functions as a very small computer when it stands alone, and also functions as a slave PC card when it is inserted into a host PC to interface with. This article describes a method for ChipCard to have its own expansion unit through its PC card connector, with ChipCard side as a host (Fig. 1). By using the card detect pins, which are originally static signal, as input/output, whether the unit connected to the PC card connector is the host PC or an expansion unit can be determined, with keeping compatibility with the PC card standard when a ChipCard is inserted into the host PC.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Bus Expansion for Chip Card

      ChipCard is a device in the form factor of Personal Computer
(PC) card, which functions as a very small computer when it stands
alone, and also functions as a slave PC card when it is inserted into
a host PC  to interface with.  This article describes a method for
ChipCard to have  its own expansion unit through its PC card
connector, with ChipCard side  as a host (Fig. 1).  By using the card
detect pins, which are originally  static signal, as input/output,
whether the unit connected to the PC card  connector is the host PC
or an expansion unit can be determined, with keeping compatibility
with the PC card standard when a ChipCard is inserted into the host
PC.

      On an usual PC card, the card detect signal pins, "-CD1" and
"-CD2" are tied down (Fig. 2-a).  The host PC's input pins for these
signals are pulled up (Fig. 2-b), so that it reads High when the card
socket is empty and Low when a card is inserted.  On the expansion
unit for ChipCard, these two signals are tied together but not
connected GND nor Vcc (Fig. 2-d).  ChipCard's -CD1 is an output, and
-CD2 is a input with an open collector output and a pull down
register, whose value is large enough with respect to the PC's pull
up register (Fig. 2-c).

      In a normal state, both -CD1 and -CD2 should be lowered (CD1 =
1, -CD2_HIZ = 1).  In this state, the ChipCard acts as a normal PC
card.  If inserted to the host PC, it is detected as a normal PC
card.

      When ChipCard's software want...