Daytronic Corporation - System 10 - FIFO Buffer Memory Card

This card is for use in System 10 "A-sized" mainframes (only)—that is, in members of the "10KU," "10K1/10K2," and "10K4T" mainframe families. Its purpose is to provide nonvolatile buffer storage of serial-ASCII outputs issued from the mainframe's Computer Interface Port. These outputs are normally data transmissions produced in response to standard system mnemonic commands like DUMP (DMP), STREAM (STR), HARD COPY (HCY), etc. However, they may also include the Central Processor's response to standard system interrogations.

With battery-backed RAM, the FIFO buffer card is ideal for applications where it's impractical to connect a computer, printer, recorder, or other receiver directly to the mainframe while data is being acquire—as, for example, in "on-the-road" vehicle performance testing, using a DC-powered mainframe.

Via its 20-pin FIFO Computer Port, the 10AFIFO connects both to the mainframe's Computer Interface Port and to an external RS232C receiving device (dual cable supplied). Protocol for the latter interface is user-selectable (up to 153.6K baud).

The 10AFIFO receives instructions through its FIFO Computer Port (only), passing on to the mainframe's Central Processor all computer-entered commands not relating it itself. FIFO setup parameters are written to EEPROM, as enabled by the "software" setting of a special system logic bit.

As shown in the table below, there are—in addition to the mnemonic commands for I/O-mode setup and the initiating of FIFO transmissions—specific commands for reaccessing the FIFO memory (should the 10AFIFO card be removed from the mainframe); for "true erasure" of memory contents, using a physical overwrite technique; and for allowing System 10 interrogation responses to temporarily bypass the FIFO memory.

The 10AFIFO memory can be made to receive and store transmissions from the mainframe's Computer Interface Port continuously, rewriting over the oldest contents of the 10AFIFO's main memory when the buffer is full (this is the "destructive data input" or "cyclic" mode). Or it can be made to receive and store system outputs continuously until the memory is full, after which it will receive and store an output only when the required memory space becomes available (this is the "nondestructive data input" or "fill" mode).

When the 10AFIFO is in "open output" mode, it will continuously transmit the oldest contents of its main memory via its output buffer. When in "gated output" mode, however, it will transmit only when and as instructed by a DDO or NDO command (see table). In either output mode, the receiving device can instruct the 10AFIFO to halt or resume transmission (by issuing an ASCII DC1 or DC3 character, respectively).

Mnemonic Commands Applying the Model 10AFIFO

DDI

Places the 10AFIFO in DESTRUCTIVE DATA INPUT ("cyclic") mode. The 10AFIFO main memory will continuously receive and store consecutive data records from the mainframe's Computer Interface Port, rewriting over the oldest contents of the memory when it is full.

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NDI

Places the 10AFIFO in NONDESTRUCTIVE DATA INPUT ("fill") mode. The 10AFIFO main memory will receive and store consecutive data records from the mainframe's Computer Interface Port until the memory is full, after which it will receive and store a data record only when the required memory space becomes available.

XEN

Places the 10AFIFO in "open" (TRANSMISSION ENABLE) output mode. The 10AFIFO will continuously output the oldest contents of its main memory via the output buffer. In this mode, the DDO or NDO command will have no effect.

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XDS

Places the 10AFIFO in "gated" (TRANSMISSION DISABLE) output mode. The 10AFIFO will subsequently transmit its oldest "main-memory" contents or the contents of its output buffer only when so instructed by a DDO or NDO command, respectively.

DDO

Initiates a DESTRUCTIVE DATA OUTPUT by causing the 10AFIFO to output through the FIFO Computer Port the oldest data record in its main memory, one time only. A copy of this data record is retained in the 10AFIFO's output buffer, the previous contents of which are destroyed. This command is effective only when the 10AFIFO has been placed in "gated" output mode by application of the XDS command.

(Click on image to enlarge)

NDO

Initiates a NONDESTRUCTIVE DATA OUTPUT by causing the 10AFIFO to output through the FIFO Computer Port the data record currently in the output buffer, one time only. This data record is retained in the output buffer, and may be retransmitted by subsequent applications of the NDO command. This command is effective only when the 10AFIFO has been placed in "gated" output mode by application of the XDS command.

(Click on image to enlarge)

BYP = ON
or
BYP = OFF

Initiates or cancels "FIFO bypass" for all outputs from the mainframe's Computer Interface Port. This command is principally used to obtain quick responses to "read" commands received at the 10AFIFO's FIFO Computer Port which do not related to the 10AFIFO itself; each such answer is transferred directly to the 10AFIFO's output buffer. When the bypass is ON, the 10AFIFO's standard input and output modes (DDI, NDI, XEN, and XDS) are suppressed.

(Click on image to enlarge)

RFM

Allows the user to REACCESS the FIFO MEMORY by restoring access to all data records currently contained in the 10AFIFO. If the 10AFIFO is in "open" output (XEN) mode, it will retransmit all data records in its main memory, starting with the oldest. If it is in "gated" output (XDS) mode, it will retransmit the oldest data record in memory when the DDO command is next entered.

FCL

CLEARS the FIFO memory by initiating a "true erasure" of all memory contents (including any contents of the output buffer), using a physical overwrite technique. This makes impossible the subsequent retransmission of 10AFIFO contents via the RFM command.

MOD

Reads the current 10AFIFO input and output MODE settings (as established by the DDI, NDI, XEN, and XDS commands).

CSF = SUM

Stores the CHECKSUM of the 10AFIFO's existing EEPROM contents and the checksum value of its existing RAM contents

CSF

Returns the results of CHECKSUM FIFO evaluations: whether the CODE EEPROM checksum is equal to the prestored value; whether the EEPROM checksum is equal to the value stored by the last CSF = SUM command; and whether the RAM checksum is equal to the value stored by the last CSF = SUM command.