Last month I wrote a bit about a new toy here at WAJAJR, a TRS-80C Color Computer. Based on the most powerful eight-bit microprocessor around, the Motorola 6809, this is a fascinating computer which gives huge potential at a bargain price.
Well, I have had a chance to take a quick look at one piece of RTTY software available for the CoCo-a RTTY/CW program from Clay Abrams Software. Clay is known to us 68xx mavens from way back and has been one of a kernel of boosters for 68xx systems for many years. This looks like one fine piece of software, folks. I will have a full review next month, but for those of you who just can’t wait, let me dangle a few choice tidbits. This program will receive and transmit ATTY at all common speeds, either in Murray or ASCIl, and receive and transmit Morse at up to 99 words per minute. It has buffers for transmit, tape save, and more. Not all is golden, Clay, but I am impressed! More about this gem next month.
Not to stay stuck in one CPU vein, I have a card here from Henry Kirchmer KF4UW in Rockledge, Florida. Henry asks, “Do you know if anyone makes an interface for RTTY and CW and the software for the Timex/Sinclair 000 or new 1500 that I could use with my (transceiver)?” Well, by a stroke of serendipity, also in the mall arrived an issue of QZX, billing itself as The Journal Covering Amateur Radio and Sincliair Computers-ZX-80, Micro Ace, ZX-81, and Timex/Sinclair 1000/1500.” In the issue I received (November, 1983), articles include several for interfacing the Timex/Sinclair-type machines on RTTY and CW, with explanations of ASCIl and Murray (although they call it Baudot) code for the computerist ham. They even have a short bibliography in the back with articles in various amateur-radio magazines related to RTTY. 1 am a bit disturbed, however, that while they have a listing for 73: Amateur Radio’s Technical Journal, they do not mention this column. Oh well, 1 quess somebody at QZX reads this column-after all, I did get a copy. Anyway, interested prospective readers might drop them a line at QZX, 2025 O’Donnell Drive, Las Cruces, New Mexico 88001. A year’s subscription is $12, according to the information received. It wouldn’t hurt If you mentioned that you read about them in “RTTY Loop,” would it? Another source of RTTY for the Timex/Sinclair is Ken Carpenter KC4UG who makes a series of programs under the business name of Kentronics. That Is not to be confused with Kantronics, mind you! Well, Ken offers a series of programs, including RTTY transceive programs, Morse programs, and some amateur-radio utilities, all designed for the Timex/Sinclair 1000 or Sinclair ZX-81. His RTTY program, for example, is touted as featuring receive and transmit buffers, split-screen display, multiple baud rates for either Murray or ASCIl modes, hard-copy option, and more. Requirements include a computer with 16K or more of RAM, a RTTY I/O port, and a terminal unit capable of interfacing with TTL-level (not RS-232) signals.
That I/O port is designed around an 8250 ACIA which takes care of providing a baud clock along with converting serial to parallel and back again. Apparently, there are also transistors provided for some degree of isolation from outside voltages. No mention is made of optoisolators or the like.
Typical prices for these items are $25 for a tape of the RTTY program, guaranteed to load or it will be replaced upon return, and $70 for an assembled and tested interface unit, plus postage and handling. I have no information on how well or easily this RTTY interface operates; maybe some of you who have played with it will let me know. However, it does seem as though more is becoming available for this truly low-cost computer. If you would like more details, write to Ken at his office, Kentronics, Inc., PO Box 586, Vernon, Alabama 35592. Be sure to watch the spelling of their name, and drop ours, OK?
While I cannot speak from the experience of having used the following program myself, a letter from Jerry Weikrauch KØHZI in North Riverside, Illinois, speaks very highly of a RTTY program for the VIC-20 and Commodore-64 computers. Available from RAK Electronics, these packages feature software to tum either computer into a basic RTTY terminal and sell for under twenty dollars each. Sounds like quite a bargain! You have to provide a terminal unit or some other way to tur the receiver audio into on/off pulses and an AFSK oscillator to generate the necessary tones. If you’re interested, drop RAK a line at PO Box 1585, Orange Park, Florida 32067-1585. I don’t need to prompt you as to where to tell them you read about them, but let me know what you think if you try the software.
Going from systems that seem to have a lot written for them to the other extreme, I have a letter here from Philip Shulins WD4OSS in Daytona Beach, Florida. Phil notes that he is “drooling with anticipation” looking for a RTTY program for his Kaypro-2 computer. Well, Phil, as I have indicated here before, there have been relatively few programs, or even program announcements, that have crossed my desk for the IBM-type computers. If you can run a standard CP/M-type program, you may be able to find one on a local RBBS, but otherwise, lam afraid I draw a blank. I will keep my eyes out, though, and pass along any information I receive here to you and the rest of the gang. I have a letter here from Hughie Chavis (I can’t find the envelope, so l am not exactly sure where he is). Anyway, Hughie is trying to run a Teletype KSR-35 from his T1-99/4A computer by running data out of an RS-232 module. He writes, “The KSR-35 is set for 100-wpm serial data transfer. The lowest baud rate for the TI RS-232 module Is 110 baud. The TI RS-232 module has a PIA port in addition to the serial IO port. My question is, how do I connect the KSR-35 to the RS-232 module so the printer capability can be utilized?”
Well, there is a very basic problem with connecting these two units together; they are not speaking the same language. Forget dialects, I’m talking major languages – ASCIl and Murray are about as different as English and Hebrew. It would not be too hard to connect the parallel port of the TI interface module to a simple UART chip (such as the common 1013 variety); provide a clock circuit, and put the data out at the correct rate, but the problem remains that the data coming out of the computer is in the wrong code.
Let me explain. To begin with, realize that the “baud” designation merely refers to how many data bits per second are being transmitted. There is no relation between the “baud rate” and the type of encoding used to send the data. With plain old Murray code – the one we are all familiar with on RTTY, and the one which your KSR-35 speaks-one common speed is the so-called 60 words per minute. Now, not to go into all the math right now, each character consists of five data bits, one start bit, and a stop bit which is a tad longer than the others. This works out to 7.41 units per char- acter, with each unit being one bit of 21 ms length. Each character thus takes 7.41 times 0.021 seconds, or 0.163 seconds. In one minute, there would be 368 characters; in one second, 6.134 characters. Now, 6.134 characters per second times 7.41 bits per character (remember how the units canceled out in algebra?) yields 45.45 bits per second. This is 45.45 baud.
Without working through all this math again, trust me that the commonly called “100-wpm” speed is about 75 baud. That’s one problem, and we’re still talking five-level Murray code.
The TI computer, as most others, uses seven-bit ASCIl to communicate with the outside world. Now each character consists of a start bit, seven data bits, a parity bit, and either one or two stop bits, depending often on the hardware involved. These bits do not in any way, shape, or form correspond to the RTTY Murray code. What you will have to do is convert the ASCIl coming out of the computer to Murray, shift speeds, then put it in a form that the KSR-35 can accept.
I’ll let you think on that one for a bit, and next month I’ll show you a few ways to accomplish this task. While software techniques have been the most popular with users of some computers, the limited access to the T1-99/4A’s innards might well hamper that approach, and I feel that you might be inclined to stick with a totally out-board approach. Let me get out the drafting board and see what develops.
Now, a note to all of you who have tried to call me on the phone over the last few months. Please don’t. It’s not that I dislike your calls, but l am a physician and my home number is not listed. It will stay that way for professional reasons. My office number, or answering service, has fielded a number of RTTY calls in past months, and they don’t always know what to do with them. So, if you have a question or would like to offer some words to the column, jot them down on a card or letter and mail them to me at the above address. If you would like a reply, enclose a self-addressed, stamped envelope, and I shall try to answer you as soon as possible. I try to scribble something down, usually at the bottom of your letter, and return it to you within a few days, unless I need to hold it for information, publication, or the like. I love hearing from you all, pro and con, and it is often your input, suggestions, and questions which make many readers write that the first thing they look for when they get their copy of 73 is “RTTY Loop.”