Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!columbia!caip!clyde!cbatt!cbosgd!ucbvax!SU-SCORE.ARPA!G.ABRAMS From: G.ABRAMS@SU-SCORE.ARPA (Info-Atari Moderator) Newsgroups: net.micro.atari16 Subject: [FGCBA10%BLEKUL11.BITNET@WISCVM.WISC.EDU: re: 520ST parallel printer port doubles characters?] Message-ID: <12234258938.40.G.ABRAMS@Score.Stanford.EDU> Date: Wed, 27-Aug-86 19:51:32 EDT Article-I.D.: Score.12234258938.40.G.ABRAMS Posted: Wed Aug 27 19:51:32 1986 Date-Received: Thu, 28-Aug-86 23:12:20 EDT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 60 Return-Path: Received: from WISCVM.WISC.EDU by SU-SCORE.ARPA with TCP; Wed 27 Aug 86 06:39:49-PDT Received: from (FGCBA10)BLEKUL11.BITNET by WISCVM.WISC.EDU on 08/27/86 at 03:42:54 CDT Date: Wed, 27 Aug 86 10:42:23 SET To: info-atari16-request@su-score.ARPA From: FGCBA10%BLEKUL11.BITNET@WISCVM.WISC.EDU Subject: re: 520ST parallel printer port doubles characters? DEER JAN, THE PROBLEM OF THE DDOOUUBBLLEEDD CHARACTERS LIES IN THE STROBE PIN NUMBER 1 THAT GOES TO THE PRINTER. THE PULSE IS TO LONG SO AFTER THAT THE BUSY-LINE HAS DROPPED THERE IS STILL A STROBE PULSE AND THE CHARACTER WILL BE PRINTED AGAIN. ______ STROBE ---------I I--------------- I I I-----------------I I------------I I I BUSY-------------I I------------------- INTERUPT THE STROBE LINE AND PUT THE FOLLOWING SCHEME BETWEEN IT THEN THE PROBLEM HAS TO BE SOLVED. I +5V I R = 10K I I 2.2NF I--II--I +5VI I I I I I I---.----.------.-----.----.----.----.----.----I I 16 9 I I 74LS123 I I 1 8 I I---.----.------.-----.----.----.----.----.----I I I I I I I I------I I I I I I I I +5V I ----- R = 100 I GND I I I I I I STROBE IN STROBE OUT FROM COMPUTER TO PRINTER -------