It is expected that a large number of SAGE II users will want to port software from a computer system that does not support a compatible storage media. The most universal method of solving this problem is by setting up a communication link over an RS232 channel. Unfortunately setting up this type of communication is usually easier said than done. The number of details which must be coordinated usually require an experienced user. These notes and the accompanying software should help in the task of successfully interconnecting another system to a SAGE II computer.
The programs REMOUTTEST and REMINTEST are routines which are intended to check out an RS232 remote channel between two p-System computers. The routines SEND and RECEIVE are simple programs to communicate the image of a device between p-System computers. The program TEXTIN is used to receive ASCII text and store it in a .TEXT file. TEXTIN is typically used to transfer source programs from a non p-System environment. The program REMTALK is provided by Softech Microsystems (on an as-is basis) and provides individual file transfer capabilities between two p-System ertvironments.
The typical scenerio is to use REMOUTTEST and REf.IINTEST (or equivalent methods of sending and receiving characters) to check out the remote RS232 channel connection. If the foreign (non SAGE) system supports the p-System, then REMTALK may already be available and can be used to transfer files. The routines SEND and RECEIVE are short and may be easily typed into a foreign p-System computer. If information is only to be transfered to the SAGE system then only SEND (a one page program) is required on the foreign system. If files must be transfered to the foreign system, then RECEIVE may be typed in and used to transfer the more general (and larger) REMTALK program. Source files from a non p-System environment are usually received by the TEXTIN program. Text files may be output to a non p-System environment by using the Filer to transfer them to device REf.l0UT: •
HARDWARE INTERCONNECTION SECTION VIII.l
VIII.l BARDlfARB IftBRCOlOfBC'!IOR
Four connections are important when interconnecting the Modem port (DB-25 connector) to another computer system. The signal Ground should be connected to pin 7. The Transmit Data output is from pin 2. The Receive Data should g'o to pin 3. The Clear to Send on pin 5 must be held in the +12V state. Clear to Send should generally not be used for low level handshaking (see writeup under Modern Port). A +12V source is available on pin 9
of the DB-25 connector.
Data Set Ready on pin 6 may be used for low level handshake control of the transmit direction. No signal is currently available from the receive side to control the far end transmission.
VIII.2 CBARREL CORPIGURATIOR
Many var iations of low level da ta forma t ar~ available on the remote channel. The utility program SAGEUTIL is used to alter the conf iguration of the remote channel. The following signal format items must be identical between the two computer systems.
Baud Rate Parity
Number of Stop bits Number of Data bits
(no parity, even parity, odd parity) (1-, 1.5, or 2)
(7 or 8)
The SAGE computer system will ignore characters which generate detectable low level (parity, framing, and overrun) errors by the USART. Descrepancies in the configuration mayor may not generate USART detected errors. Thus spme characters may be received (possibly with incorrect values) while others will be totally ignored.
The XON/XOFF and Data Set Ready options must be disabled unless these handshaking options are desired.
SAGE II USER'S MANUAL [1.3] 1982
VIII.3 COMMUNICATION HANDSHAKING
COMPUTER INTERCOMMUNICATION COMMUNICATION HANDSHAKING SECTION VIII.3
Handshaking is a method of two computers exchanging information to insure that they are both working on the same thing. (experimentally) to force a delay between characters. This technique may be used to slow down transmission instead of receive directions (see remote channel configuration section).
The SAGE II transmitter also can be set up to monitor the Data
COMPUTER
CO~n1UNICATION HANDSHAKING SECTION VIII.3
Examination of the REMTALK program indicates that it does a more complete job in high level handshaking. All characters are received in groups at the low level and processing is performed between transmission of blocks. High level commands a~e
exchanged between transmission of blocks to coordinate the communication.
VIII.4 Using REMIRTEST and REMOUTTEST
Two versions of REMINTEST are provided, one for Version IV (or greater) p-Systems (with the UNITSTATUS procedure) and one for pre Version IV systems. Both routines echo characters received from the remote input channel to the terminal. The Version IV variation allows a Q to be typed to exit the routine while the second variation might need to be reset. Note: for most non-Sage systems, in order to use the p-System Break key, a character must arrive on the remote- channel before the BIOS will return and let the system recognize the break.
REMINTEST will echo all characters received on the remote channel to the terminal. The terminal data rate must be the same or higher than the remote channel data rate in order to keep from losing characters. Note tha t even if the baud ra tes are the same, if less bits are received on the remote channel (no parity, less stop bi ts, less data bi ts, etc.) then the, terminal will eventually get behind. Also the clock rates may be slightly different (even with the same baud rate and number of bits) which could cause missed characters. The constant, DELAY, at the beginning of RE~10UTTEST may be increased to slow down transmission.
REfl10UTTEST asks 'Output how many lines? • Each line contains upper and lower case letters and the ten numeric digits followed by a carriage return.
Note: REMINTEST may be used to monitor the output of SEND or any other source that does not require high level handshaking.
SAGE II USER'S MANUAL [1.3] 1982
VIII.5 Using SEND and RECEIVE termination characters are sent to synchronize the communication.
A short pause is made every 32 blocks for the receiving end to
USING TEXTIN SECTION VIII.6
VIII.6 Using TEX~IN
The program TEXTIN handles text which is typically output by a non p-System computer. The operations of TEXTIN are split into two parts to maximize the possible receive data rate. The main prompt line of the program is:
C(onvert, R(eceive, Q(uit ?
The R(eceive option is used to receive characters on the remote serial channel input and store them in a file. The C (onvert option should be used on a raw character file to convert the
information into the standard UCSD p-System .TEXT file format.
The R(eceive option will query:
Receive text into what file?
Once the file is set up the routine will prompt:
A(bort or T(erminate receiving?
For each block of characters written to disk a period is printed on the screen. No End-of-File character is recognized. To indicate to the program that all data has been transfered, the 'T' character should be typed on the keyboard. This indicates that the input should be terminated and the file should be saved.
The 'A'character should be typed on the keyboard to immediately abort the program without saving the data.
After termination the data should be C(onverted to the p-System
".TEXT" file format. The routine will query:
Source file for conversion?
Destination file for conversion?
The source file should be the file specified for the R(eceive process (above). The destination should be the final .TEXT file to be used by the Editor, etc. The conversion process strips out line feeds which are typically output for printers or terminals but are not needed in the .TEXT file format. Null (zero) characters are stripped out. Null characters are typically added in at two block boundries to prevent lines from crossing a double block boundry. Lines which exceed 255 characters wi thout a carriage return will have a carriage return inserted and generate a message 'Line> 255 characters'.
SAGE II USER'S MANUAL [1.3] 1982