HP 2500c Service Manual - Page 20

Specifications IEEE 1284 Pinout Information Any standard IEEE 1284 compliant printer cable will work with the printer. The customer can order the HP IEEE 124 Compliant Parallel Interface Cable C2950A (2 meters) or C2951A (3 meters). See Ordering Parts in Chapter 12 for ordering information. PIN NUMBER PIN ID DESCRIPTION 1 HostClk Used in a closed-loop handshake with PeriphAck to transfer data or address information from the host to the peripheral device. 2 - 9 AD1 - AD8 Host to peripheral device or peripheral device to host address or data. Data 1 is the least significant bit (bit 0). 10 PeriphClk Used in a closed-loop handshake with HostAck (nAutoFd) to transfer data from the peripheral device to host. 11 PeriphAck The peripheral uses this signal for flow control in the forward direction. PheriphAck also provides a ninth data bit to determine whether command or data information is present on the data signals in the reverse direction. 12 nAckReverse The peripheral drives this signal low to acknowledge nReverseRequest. The host relies upon nAckReverse to determine when it is permitted to drive the data signals. 13 Xflag This is used by the peripheral device to reply to the requested extensibility byte during the negotiation phase. 14 HostAck The host drives this signal for flow control in the reverse direction. It is used in an interlocked handshake with PeriphClk. Host Ack also provides a ninth data bit used to determine whether command or data information is present on the data signals in the forward direction. 16 Logic Ground Logic board ground. 17 Chassis Ground Chassis Ground. 18 Peripheral Logic High This signal is used to provide +5V high logic. 19-30 Ground These pins are tied to signal ground 31 nReverseRequest This signal is driven low to place the channel in the reverse direction. While in ECP mode, the peripheral is only allowed to driver the bi-directional data signals when nReverseRequest is low and 1284 Active is high. 1-12 Product Information