HP-65 card reader - purpose of WE pin

[teenix]

(05-02-2019 04:03 PM)albertofenini Wrote:  Dear all,

We will perform soon the switch test, checking that the WPS switch closes correctly when the
card is inserted.

However, what is the purpose of the WE pin in the card reader PCB ?
Has it something to do with Write Enable (??) and is a possible cause of malfunctioning ?
How can we check that ?

If the WPS switch is faulty (open circuit), you should get "Error" displayed when trying to write a card, because the CRC will interpret that as a write protected card. For a short circuit, the card should write ok, even for write protected cards.

In normal operation, if WPS is HI when HDS goes LO, the card is write protected.

The WE pin is controlled by the CRC chip. It goes Logic HI when the card chip is to write a card and Logic LO when it is to read a card.

cheers

Tony