SECTION 6. 9-PIN SERIAL INPUT/OUTPUT

from enabled peripherals in that they are not enabled solely by a hardware line (Section 6.2.1); an SD is enabled by an address synchronously clocked from the CR10 (Section 6.6).

Up to 16 SDs may be addressed by the CR10. Unlike an enabled peripheral, the CR10 establishes communication with an addressed peripheral before data are transferred. During data transfer an addressed peripheral uses pin 7 as a handshake line with the CR10.

Synchronously addressed peripherals include the CR10KD Keyboard Display, SM716 and SM192 Storage Modules, SDC99 Synchronous Device Interface (SDC99), and RF95 RF Modem when configured as a synchronous device. The SDC99 interface is used to address peripherals which are normally enabled (Figure 6.2-1).

from interrupting data transfer to a pin-enabled print device.

6.3 RING INTERRUPTS

There are three peripherals that can raise the CR10's ring line; modems, the CR10KD Keyboard Display, and the RF Modem configured for synchronous device for communication (RF-SDC). The RF-SDC is used when the CR10 is installed at a telephone to RF base station.

When the Ring line is raised, the processor is interrupted, and the CR10 determines which peripheral raised the Ring line through a process of elimination (Figure 6.3-1). The CR10 raises the CLK/HS line forcing all SDs to drop the ring line. If the ring line is still high the peripheral is a modem, and the ME line is raised. If the ring line is low the CR10 addresses the Keyboard Display and RF-SDC to determine which device to service. (Section 6.6)

After the CR10 has determined which peripheral raised the Ring line, the hierarchy is as follows:

A modem which raises the Ring line will interrupt and gain control of the CR10. The one exception is that a modem cannot interrupt an active RF- SDC. A ring from a modem aborts data transfer to pin-enabled and addressed peripherals.

The CR10KD raises the ring line whenever a key is pressed. The CR10KD will not be serviced when the modem or RF-SDC is being serviced.

The ring from the CR10KD and RF-SDC is blocked when the SDE line is high, preventing it

FIGURE 6.3-1. Servicing of Ring Interrupts6.4 INTERRUPTS DURING DATA TRANSFER

Instruction 96 is used for on-line data transfer to peripherals (Section 4.1). Each peripheral connected to the CR10 requires an Instruction 96 with the appropriate parameter. If the CR10 is already communicating on the 9-pin connector when Instruction 96 is executed, the instruction puts the output request in a "queue" and program execution continues. As the 9-pin connector becomes available, each device in the queue will get its turn until the queue is empty.

Instruction 96 is aborted if a modem raises the Ring line. Data transfer to an addressed peripheral is aborted if the ring line is raised by a CR10KD or RF Modem configured as a synchronous device. Transfer of data is not resumed until the next time Instruction 96 is executed and the datalogger has exited telecommunications.

The *8 Mode is used to manually initiate data transfer from Final Storage to a peripheral. An abort flag is set if any key on the CR10KD or terminal is pressed during the transfer. Data transfer is stopped and the memory location displayed when the flag is set. During *8 data transfer the abort flag is checked as follows:

6-3