Plug the 9 Volt battery into the clip located on the back of the DB25 plug cabled to the LCD display module. Plug the DB25 plug into the parallel port on an IBM (or compatible). Note which port you plugged it into I.E. LPT1: LPT2: or LPT3:. Then insert the disk into drive A: and issue the appropiate command LCD1 LCD2 or LCD3 depending on which port you plugged the LCD into. A:\>lcd1 Note: If you have a Hercules vidio card or a Monochrome vidio card with the built in parallel port use LCD3 not LCD1. Next press both the SHIFT key and the PRINT-SCREEN key at the same time. The LCD display should have a flurry of activity printing on the LCD what ever happened to be on your screen at the time. Don't expect it to have any residual info on it when it stops, the last thing it printed was probably a whole display's worth of spaces I.E. the last line of your screen. If you press everything that you type and all of MS DOS's responses will echo on the LCD display. Pressing again turns off the echo. Some characters in the extended ASCII set are Japanise so don't be too supprised. The driver on this disk does not fully support the LCD display partly because the parrallel port on the IBM (or compatible) is allmost never a listener and even when it is it draws so much current (150 ohm pullup resistors) the display would go poof trying to drive it. So reading the LCD using the scheme I have chosen is out of the question. There are also many other tricks these LCD's have up there sleeves like graphics capability that I chose not to support. These can still be accomplished by you, by writing your program so that it directly writes to the port, but this requires an intimate understanding of the parrallel port and the LCD display, it therefore is beyond the scope of this doc. Sending a 0C hex or 12 decimal or a Form-Feed character to the LCD display will initalize the display electronics and clear the LCD display putting a blinking cursor in the upper left hand corner. Static electricity or an electrical spike especially on a long cable can send the LCD display off to the twilight zone! You are advised to send Form-Feed's often. That will allow the LCD to recover from a glitch. From MS DOS the command to do that is. C:\>echo ^L>prn: where ^L is a I.E. Form-Feed. From BASIC the command is. LPRINT CHR$(&H0C); or LPRINT CHR$(12); The BASIC version of the command is preferable since MS DOS's ECHO command also outputs the gratuitus carrage return line feed whither you want it or not. The driver automatically wraps at the 24th column and if allowed to wrap twice (once for each line) it over writes the line it falls on. This is normal but it looks pretty weird. I have included a little demo program written in BASIC (for ease of understanding) called Colliding Arrows. DB 25 male Densitron LCD Parrallel LM23B2C24CTW Port 2 Line Display 1 컴컴컴컴컴컴컴컴컴컴 6 2 컴컴컴컴컴컴컴컴컴컴 7 3 컴컴컴컴컴컴컴컴컴컴 8 4 컴컴컴컴컴컴컴컴컴컴 9 5 컴컴컴컴컴컴컴컴컴컴 10 6 컴컴컴컴컴컴컴컴컴컴 11 7 컴컴컴컴컴컴컴컴컴컴 12 8 컴컴컴컴컴컴컴컴컴컴 13 9 컴컴컴컴컴컴컴컴컴컴 14 16 컴컴컴컴컴컴컴컴컴컴 4 25 컴컴컴컴컫컴컴컴컴컴 1 쳐컴컴컴컴� 5 旼컴컴컴컴컴커 1N4733 쳐컴>쳐컴컴 2 컴켸 � � � � � 9 Volt 1.2K ohm 읕�\/\/\컴� 3 컴컴컴눴납납냉컴� Battery (-) � � � � (+) The Densitron 2 line X 24 column LCD display (number LM23B2C24CTW) shown above uses a negative driven contrast control voltage (pin 3). Not all of these displays work that way. Asserting negative voltage on a display not designed for the wide cone viewing angle (negatively driven) feature would damage the LCD display module. An alternative connection diagram is shown below for LCD displays that do not require negative contrast bias. DB 25 male AND 771 LCD Parrallel 2 Line Display Port Module 1 컴컴컴컴컴컴컴컴컴컴 6 2 컴컴컴컴컴컴컴컴컴컴 7 3 컴컴컴컴컴컴컴컴컴컴 8 4 컴컴컴컴컴컴컴컴컴컴 9 5 컴컴컴컴컴컴컴컴컴컴 10 6 컴컴컴컴컴컴컴컴컴컴 11 7 컴컴컴컴컴컴컴컴컴컴 12 8 컴컴컴컴컴컴컴컴컴컴 13 9 컴컴컴컴컴컴컴컴컴컴 14 16 컴컴컴컴컴컴컴컴컴컴 4 25 컴컴컴컴컫컴컴컴컴컴 1 쳐컴컴컴컴� 5 旼컴컴컴컴컴커 1N4733 쳐컴>쳐컫컴 2 컴켸 � 9 Volt � 읕� 3 � � � � � 910 ohm 읕�\/\/\컴컴컴컴컴컴눴납납냉컴� Battery (-) � � � � (+) Note: Pin 3 is actually intended to be adjustable to get the best possible contrast. These are simplified wiring diagrams for simplified people. The SED1278F appears to be equivelent to Hitachi HD44780A00 at least from the point of view of the interface and driving software. 20324 appears to be the part number of the displays for which this program was origonally written. The vendor is as yet unknown to me. Pin 5 of the LCD Module the R/W is GROUNDED. This is very important If the LCD Module were ever allowed to assert data against the non tristateable IBM parallel port the LCD Module would surely loose the fight. If you run debug as follows C:\>debug lcd3.com the lcd driver will be loaded at 100 hex at a paragraph of MS DOS's choice. Debug will respond with the following minus sign prompt. - If enter the following command. -d100 200 the first 100 hex bytes will be displayed in hex on the left and on the right the following message will be displayed solely for the benifit of a fine hacker like yourself. .........Setting params in DEBUG Byte 100-102H is JMP inst. 103 is low byte of port address. 104 is high byt of port address. 105 is max column numbr I.E. 19H for 24 column wide LCD Good luck... I will leave you to puzzle the Cosmic One-ness of this truth. J. K. P.