PACKET89.DOC _____________________________________________________________________ Packet89 is a software interface for use between the Heath Z/H-89 or Z/H-90 and a packet TNC. The program may also work on an H-8 depending upon which I/O board the H-8 has. It is a derivative from the MODEM controller called "PLINK". Three files are used, Packet89.COM, Kernel.COM and Protocol.DTA. The first, Packet89, sets the I/O ports for the interface. It allows the user to reset the interface BAUD and the word characteristics (size, number stop bits, parity, etc.). The default port is the DTE port at address 330. If someone else wants a different port he'll have to get it through modification of the source code. The default interface baud is set at 300. On my H-89 this works well even though my TNC/transceiver interface is running at 1200 baud. At 600 baud, if I try to save to the buffer, an occasional character is lost, to buffer, CRT, and printer. At 1200 baud, again, if I try to save to buffer, the computer simply can't handle it. If, on the other hand, incoming text is not going to buffer, i.e., only to CRT and the lineprinter, the computer can handle 1200 baud. This situation was an unknown at the time the program was written, being recognized only as an attempt was made to run at 1200 baud. Because this program can still be used effectively as a telephone modem driver and to permit such use I decided to keep the 1200 baud. Another H-89 may function properly at 600 baud. The program allows for use of a control interface protocol between the TNC and computer. The user establishes this protocol when the program is loaded. In order to transfer a file from disk to TNC, there must be agreement between the computer and the TNC. Normally this is achieved by selecting "continuous transmit"; that is, no protocol by entering "KERNEL U" when requested. Many TNC's will operate in the "X-ON/X-OFF" mode. You may want to try it although I've no idea what will be gained. It, the "LINE FEED Character" and the "BELL Character" protocols have been retained in order to permit the continued use of the program as a telephone MODEM controller. USING THE PROGRAM: Run "Packet89" and respond Y or N when asked if the default protocols are acceptable. (They normally should be.) If a change is desired, enter "N" and follow instructions. When asked about interface protocol select "1" (normally) and enter "KERNEL U" . PIE works quite well to prepare a file before transmitting it via packet If you choose to do this, however, recall that most BBS's ask for CTL-Z at the end of the file. I don't include the CTL-Z in the file but add that manually as soon as I see the "FILE TRANSFER COMPLETE" note on the CRT. I'm afraid that PIE will strip the 8th bit and mess up the "CTL". (Anyhow, by using this technique, I avoid any risk.) I have included a copy of KERNEL.ASM for the use of anyone who has to change the I/O port (or anything else.). There's no reason to muck about with PACKET89 so I didn't include the assembly language version. You should never have to get involved. NOTE: If you don't get satisfactory operation of the disk I/O or the line printer, check your CONFIGUR.COM. Make sure of the ports and the bauds selected for the printer and the TNC. Double check to make sure that your TNC and the program default "PARMS" agree (7 bits, 1 stop, even parity.) These are easily changed by rerunning PACKET89, setting new PARMS, and saving them to disk. For whatever it's worth, on a SSSD (10 hole) disk I have PACKET89.COM, KERNEL.COM, PROTOCOL.DTA, PIE.COM and SWEEP.COM and room for temporary storage of files received or to be sent. I find this gives me maximum flexibility in all modes and plenty room on the disk. CONFIGUR.COM is set to run PACKET89 on cold boot. I'm making the program available to anyone who requests it via a BBS advisory. It should be ideal for MARS or RACES. Feel free to pass it along if you want. 73s RAY, N6UE