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UnderColor, Volume 1, Number 5, February 20, 1985

  • Title: Defusr
  • Author: Terry Kepner
  • Synopsis: Q&A
  • Page Scans: Link


I have been trying to get information on what I would need to be able to communicate with some bulletin boards. I know nothing more than that I need a modem (which I knew in the beginning). I would also I like to know if it is expensive to communicate with a bulletin board.

What would be the best modem to buy for a 16K Extended Color Basic TRS-80?

Doug Eddins

Gulf Breeze, FL

You need a computer, a modem, access to a

telephone line, and a telecommunications program, such as Colorcom/E. When you have all these assembled together, load the telecommunications program and set the RS-232 parameters (either 300 baud, seven bit words, one stop bit, and even parity; or 300 baud, eight bit words, two stop bits, and no parity). Most bulletin boards use 300, 7, 1, and even. Most Color Computer specific boards use 300, 8, 2, and none.

Expense depends on whom you call. The only charge for most public BBS's is the phone call charge. Private databases that require membership charge anywhere from $6 an hour up to $300 an hour.

I currently own a 16K Extended Basic 1.0 Color Computer purchased in December 1982. Wanting

to upgrade to 64K without the $70 plus $15 installation charge, I opened my computer to find out which revision board I own. Since nothing was printed below the cartridge port, I looked to the lower left hand corner of the board to see this printed: TRW/CG1159V1 Rev-NC. I assume that NC is my revision board, but I had thought that NC and ET boards were only used in the TDP System 100. Then I looked back to the Review section TCCM’s first issue — March 1983 — where was explained the procedure for upgrading to 64K. The article mentions three jumpers, two bare staking pins, a more pronounced clicking when the computer or tape recorder is tuned on, the PIA ’s numbered U17 and U18 and the Basic and Extended Basic chips being moved to the center of the board. This all perfectly describes my board.

I would appreciate the method for a 64K upgrade of this computer being printed, and I hope that it will help other confused NC or ET revision board owners, if that is, in fact, what I own. If it is true, I would like to know where I can get a new technical manual.

Since I purchased my computer with the understanding that it was "normal, " do I have the right to the manual, two joysticks and Super-Bustout ROMpak that come with it? Mentioned in the article in the first issue of The Color Computer Magazine was the cutting-out of eight capacitors. Please go into detail about these, for I have no idea of what was being talked about. Also, I have Extended Basic 1.0, which originally was Basic 1.1. Is Extended Basic 1.1 better? If so, how can I get a new chip?

D. Barbier

Cheshire, CT

The upgrade to 64K for the NC computer was covered in the October 1983 issue of The Color Com-

puter Magazine, in Dennis Kitsz’s Custom Color Column, plus corrections. Write to Dennis if you have no access to the article.

You can get a technical manual from Tandy National Parts, 900 E. Northside Drive, Fort Worth, TX 76102, 817-870-5662. Mastercharge and Visa are accepted and each order includes a $1.50 handling charge. Ask for the Color Computer Technical Manual NC revision update.

Just because you have the NC version doesn’t mean you get the accessories that came with the TDP-100. Remember that the TDP-100 cost more than the Color Computer.

The only ROM revisions you need to worry about are in Standard Basic. The 1.1 ROM corrects some problems in the 1.0 ROM. The 1.3 ROM is for the new white-case Color Computer. Since you already have the 1.1 ROM, you don't need to upgrade.

I recently sent you a question concerning adapting a Racal-Vadic modem to the Color Computer.

You said in your reply that you did not have access to an IBM 8775 terminal or the above modem, so I probably didn’t supply you with enough information concerning the modem (I thought it was a common modem). Enclosed you'll find a little more information from the operation manual.

From what you described (and what I read since) am I correct to say this modem will not work with the CoCo because of its 2400 bps synchronous operation? What’s the difference between baud and bps?

Note the VA2455-series (from enclosure) has a 75 or 150 bps asynchronous secondary channel. Is there any hope if I get my hands on one of these?

Samuel Murphy, Jr.

Burlington, NJ

While the Color Computer can work at 2400 baud, I don't think it will in synchronous operation (which allows data to follow simultaneously in both directions).

Assuming the Racal-Vadic uses standard RS-232C connections, all you have to do is set the Color Computer to the 150 bps mode (POKE 149,1;POKE 150,110) and make a cable that connects the 4-pin DIN connector to a DB25 connector.

Unfortunately, this will make it almost impossible to use on bulletin board systems because most of them use modems set to either 300 baud or 1200 baud.

Your best choice is to just get a standard 300 baud modem (the Volksmodem is inexpensive and available at most computer stores, the R/S modems are more expensive and work the same).

BPS (bits per second) is a slightly more descriptive acronym for baud. Three hundred baud translates to 300 bps. Translating those to characters-per-second is harder since you must know the word-size, number of start and stop bits, and if parity-checking is available.

*Ed's Note: Info from readers informs us that the Racal-Vadic VA 2450 is a 2400 bps direct-connect synchronous modem. It is Bell 201 b or c compatible. It requires an asynchronous computer operating at 300 or 1200 baud, similar to the Vadic 212.