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UnderColor, Volume 1, Number 1, December 10, 1984

  • Title: Defuser
  • Author: Terry Kepner
  • Synopsis: All you could ask for.
  • Page Scans: Link


I want to interface my printer, an Epson MX-80 F/T with GraftraxPlus, to my late model TRS-80 64K Color Computer II, at the computer's serial I/O port. I also want to maintain this printer in-line with my 32K Model I (no expansion interface).

I have written to five different suppliers of serial-to-parallel printer connectors and have received as many different offers for interfacing the printer, but none would assure me that the printer can be effectively interchanged between the two computers.

The Epson printer is modified with the Epson TRS-80 interface board (no. 8120) and the Epson Interface Cable Connector (no. 8221, #825), connected to the Model I at the left rear of the keyboard. The new 64K Color Computer is interfaced to a Color Computer II disk drive zero. I also have a R/S Parallel LPII interface (no. 1416) with cable.

l hope you can suggest a means to use both systems with the one printer.

Julian Jatyna

46 Old South Rd.

South Berwick, ME 03908

The standard Epson printer uses a parallel port, so all you need to use it on your Color Computer is a serial-to-parallel converter. However, since you’re not using an Expansion Interface with your Model I (which normally contains the Model I’s parallel port), you’re using the Epson 50-pin-to-parallel interface board. If the interface board is plugged into the Epson, inside the case, you won’t be able to use the Epson with your Color Computer unless you remove the board and use the normal parallel Epson printer port.

If you have an Expansion Interface with a parallel printer port, you could just get some type of hardware switch to select which computer was plugged into your printer, with all three devices plugged into the switch. In one position the switch connects computer A with printer, in the other position computer B is connected. You can't just plug both computers to the same printer cable without risking damage to all three devices; only one printer at a time can be electrically connected to a computer, and vice versa.

So, if the Epson/Model I interface board is outside the Epson, you can put the hardware switch between the interface board and the printer, letting you switch between the two computers (assuming you have a serial-to-parallel interface on the Color Computer).

If the interface board is inside the Epson, or the Epson doesn’t have a parallel port, then you can't use the Epson with the Color Computer.

I have a 32K Extended Basic Color Computer. Could you tell me what hardware is necessary to use the computer to make contact with my office mainframe? Are there statistical packages available which are comparable to SPSS, BMD, or similar packages?

Bonnie MacLean

280 E. Western Reserve Rd.

Poland, OH 44514

You need two things: a modem with a Color Computer RS-232 cable, to connect the Color Computer to your telephone; and some type of telecommunications program for the Color Computer, so what you type goes to the phone lines, and what the mainframe sends is displayed on your monitor. For this to work, your office mainframe must have an auto-answer modem, so it can answer the phone when you call from home, plus the necessary software for the mainframe to accept instructions from the phone line.

Since I don't know the features of SPSS and BMD, I can't make any suggestions as to the acceptability of Color Computer statistical packages. Can someone else help?

Reading the November, 1983 DEFUSR column in The Color Computer Magazine, I noticed a letter asking about 220 volt 50-cycle power and the Color Computer. I hope my experience can help. I'm stationed with the USAF in Europe and have been using my 16K revision D Color Computer, Line Printer VII, Radio Shack cassette, and Radio Shack disk drive for approximately one year here. In all this time my system has been running on 120 volt 50-cycles stepped down from 220 volt 50-cycles. I have experienced no problems using a standard step-down transformer. The 50 cycles has not changed anything noticeable. I have used my Color Computer for eight to ten hours at a time with no problems. I did have to make one very simple adjustment on the disk drive: setting the drive to 50Hz operation. The Radio Shack disk drive comes with 50/60-cycle hash marks on the drive wheel; after removing the cover, adjust the motor potentiometer until the 50-cycle marks appear to stand still when viewed under a fluorescent lamp (this can be done without voiding your Radio Shack warranty). The adjustment potentiometer is located next to the drive wheel. Without this adjustment, the drive won't recognize the DSKINI0 command.

In some situations a change from 60-cycle to 50-cycle power can cause a heating problem for the Color Computer power transformer. This is normal and over a long period of time could cause power supply problems. I haven’t experienced any problems, but my computer system is located in a fairly stable temperature environment. If the area for the computer were very warm in the summer, I would recommend taking along a cooling fan.

One last note: I have just purchased the new Radio Shack 64K Color Computer 2, the Color Computer 2 disk drive, and the Radio Shack version of OS-9. I have everything except the disk drive, and again have no power problems. Hope this information has been of help.

T.A. Ward

Box 1211

APO NY 09453

Thanks for giving us an account of your experiences overseas; my readers will appreciate it.

I read an article about an Apple computer interfaced to a laser disk player. Can the Color Computer (64K) be interfaced to a laser disk player? If so, can I use my computer to write a machine code routine to control the laser disk? Also, do the companies that sell 64K programs use the full 64K?

Wayne Tracer

Star Rt. Box 1201

Chiloquin, OR 97624

The Apple/laser disk combination requires a special hardware board plugged into the Apple mother board, with a cable running to the laser disk. This board translates instructions from the 6502 CPU into commands that can be executed by the laser disk controller. To the best of my knowledge, no one has as yet developed a hardware interface for the Color Computer to use a laser disk, although it shouldn’t be all that hard since the Color Computer ROMPak port makes all the control and data lines available.

We'll probably see this hardware configuration on the market soon, especially since the new laser disk memory units are moving out of the laboratory and into the market.

All the companies that make 64K programs require that your computer have 64K RAM before the programs will work. Most of them use the entire 64K (less system RAM requirements) for their operation. Programs that specify 32/64K usually use only 32K, but may have 64K options that only run when the extra memory is available; these programs automatically test for 64K memory.

I won a 64K Color Computer, and I recently purchased a Modem II and the Deluxe RS-232 Communications ROMpak. I read the Modem II technical manual to discover if it is capable of auto-dialing with tones or pulse. Unfortunately, the Deluxe ROMpak programs the modem for fast—pulse rotary dialing only. This is OK for local calls, but on MCI and Sprint

I'm unable to use the modem’s auto-dial function; these services require tones. Is there any way to get the tone option programmed into the modem instead of the pulse? And do you know of any BBSs in my area?

Michael S. Parker

7147 Old King Rd. S. #22

Jacksonville, FL 32217

Sorry, but the only way I know of to change the modem to tone dialing is to reprogram the communications ROMpak to use tone instead of pulse, which would require disassembling the ROM, finding the offending code, removing the ROMpak ROM, and replacing it with a new one containing the fix; none of which is easy.

Does anyone have a possible solution, or know where M.P. can get a "fixed" Communications ROM?

Here’s a short list of Color Computer BBSs in Florida: Colorama of St. Petersburg, FL, 813-345-8100; Colorama of Dunedin, FL, 813-733-2415; Ft. Lauderdale, FL, 305-525-1192; Lantana, FL, 305-533-0333; and Hialeah, FL, 305-681-8490.

I recently bought a 16K to 32K upgrade kit. The advertisement says the kit has easy instructions, but I found them hard to follow. I also had to buy extra tools to install the kit.

Please tell me how to get the memory chips off the board.

Marc Jenkins

713 Vernon Rd.

Philadelphia, PA 19119

Removing memory chips from IC sockets is simple in concept, but requires a bit of dexterity. Use a small screwdriver, or a small nail-file, to gently pry up each chip. Or you can use a commercial IC puller, which looks like an oversized pair of tweezers with the tips bent towards each other. The ends fit under the chip, and you pull the chip straight out of the socket.

When using a screwdriver to pry up a chip, be careful not to bend any of the IC's legs. If you do, carefully straighten the bent leg. If you break it off, you’ll have to replace the chip. Also, memory chips are static sensitive, so always handle them by their bodies, not the legs, and set them down on black foam or a sheet of aluminum foil. Good luck.

l’m interested in exploring the world of BBS. l own a 64K Extended Color Basic computer. At the moment I don 't have a Color Computer modem (it’s second on my wish list, after disk drive zero). I do have, however, an IBM 8775 terminal and radial-Vac modem (Model VA2450) that I use, on loan from my employer, to tie into a mainframe at work. Are there any BBSs l can access with this terminal? lf so, are there any BBSs in the south New Jersey area?

My next question is: can this modem be used with my Color Computer? lf so, what type of cables or adapters would l need?

Samuel Murphy, Jr.

9 Larchmont Dr.

Burlington, NJ 08076

I don't have access to either piece of equipment, so I can only answer in general terms: unless the IBM terminal uses special protocols, you should be able to use it with any BBS. Normal BBS communications use 300 baud, seven bit words, one stop bit, even parity, and XONIXOFF protocol. If you can’t set these parameters on your IBM terminal, then it can’t be used for normal BBS work; lf the modem is a standard RS-232 input, 300 or 1200 baud unit, then you should be able to use it with your Color Computer using the Radio Shack Color Computer RS-232 cable (which is designed to plug into an RS-232 modem). If the modem doesn’t have a DB·25 or RS·232 connector on it, you’ll have to come up with your own Color Computer-to-modem cable layout.

Has anyone successfully used a Radial—Vac modem with the Color Computer?

Here are two New Jersey BBS numbers (both are 300 baud numbers): Colorama of Highland Park, 201-572-0617; and Meadowland CoConet, 201-773-8265. (end)