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https://github.com/DerekK19/PDP-8-E-Simulator.git
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195 lines
5.8 KiB
HTML
195 lines
5.8 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<!--
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* PDP-8/E Simulator
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*
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* Copyright © 1994-2015 Bernhard Baehr
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*
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* index.html - Online help for the PC8-E Paper Tape Reader & Punch
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*
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* This file is part of PDP-8/E Simulator.
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*
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* PDP-8/E Simulator is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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-->
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html;charset=iso-8859-1">
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<title>PC8-E Paper Tape Reader & Punch Help</title>
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<meta name="description"
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content="Describes the functioning and PDP-8 IOTs of the PC8-E Paper Tape Reader & Punch">
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<meta name="AppleTitle" content="PC8-E Paper Tape Reader & Punch Help">
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<meta name="AppleIcon" content="pdp8e.png">
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<link href="styles.css" rel="stylesheet" media="all">
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</head>
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<body>
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<h1>IOTs for the PC8-E Paper Tape Reader & Punch</h1>
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<table>
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<tr>
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<th>Mnemonic<br>Symbol</th>
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<th>Octal<br>Code</th>
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<th class="left"><br>Description</th>
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</tr>
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<tr>
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<td>RPE</td>
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<td>6010</td>
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<td class="left">
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Set the interrupt enable mask for the punch and the reader.
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</td>
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</tr>
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<tr>
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<td>RSF</td>
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<td>6011</td>
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<td class="left">
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Skip the next instruction when the reader I/O flag is raised, i. e. when a new
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character is loaded into the reader buffer RBF.
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</td>
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</tr>
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<tr>
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<td>RRB</td>
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<td>6012</td>
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<td class="left">
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Read the content of the reader buffer RBF into AC (by performing a logical OR)
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and clear the reader I/O flag.
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</td>
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</tr>
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<tr>
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<td>RFC</td>
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<td>6014</td>
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<td class="left">
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Clear the reader I/O flag and RBF and start to fetch one character from the input tape
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to be loaded into RBF. The reader I/O flag is set again when the operation is completed.
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</td>
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</tr>
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<tr>
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<td>RCC</td>
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<td>6016</td>
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<td class="left">
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Load RBF into AC (by performing a logical OR), clear the reader I/O flag and RBF and
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start to read the next tape character. Microprogrammed combination of RRB and RFC.
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</td>
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</tr>
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<tr>
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<td>PCE</td>
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<td>6020</td>
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<td class="left">
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Clear the interrupt enable mask for the punch and the reader.
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</td>
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</tr>
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<tr>
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<td>PSF</td>
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<td>6021</td>
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<td class="left">
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Skip the next instruction when the punch I/O flag is set.
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</td>
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</tr>
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<tr>
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<td>PCF</td>
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<td>6022</td>
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<td class="left">
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Clear the punch I/O flag and the punch buffer PBF.
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</td>
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</tr>
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<tr>
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<td>PPC</td>
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<td>6024</td>
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<td class="left">
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Load the punch buffer from AC(4-11) (by performing a logical OR) and start to punch the
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character in PBF. (This instruction does not clear the PBF and the punch I/O flag.)
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</td>
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</tr>
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<tr>
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<td>PLS</td>
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<td>6026</td>
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<td class="left">
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Clear the punch I/O flag, clear PBF, load PBF from AC(4-11) and start to punch the
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character in PBF. The punch I/O flag is set again when the operation is complete.
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Microprogrammed combination of PCF and PPC.
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</td>
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</tr>
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</table>
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<h3>Remark</h3>
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<p>
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The IOTs RPE (6010), RCC (6016) and PCE (6020) are not available with older PDP-8 models
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(PDP-8, -8/S, -8/I, -8/L).
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</p>
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<h2>Paper Tape Formats</h2>
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<p>
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There are three basic paper tape formats commonly used in conjunction with the PDP-8 family of computers.
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The following paragraphs describe and illustrate these formats.
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</p>
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<table>
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<tr>
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<td class="left">
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<img src="ascii_tape.png">
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</td>
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<td class="left">
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<h3>ASCII Format</h3>
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<p>
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The ASCII format uses eight channels of the paper tape to represent a single character as shown in the
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diagram at left. Channel 8 is normally designated for parity check. The paper tape units of the PDP-8
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family computers do not generate parity, and channel 8 is always punched.
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</p>
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<p>
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377 (DEL, Rubout; all channels perforated) is used to “correct” typing errors and is ignored
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by paper tape rading programs.
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</td>
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</tr>
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<tr>
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<td class="left">
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<img src="rim_tape.png">
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</td>
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<td class="left">
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<h3>RIM (Read In Mode) Format</h3>
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<p>
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RIM format tape uses adjacent columns to represent 12-bit binary information directly.
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Channels 1 through 6 are used to represent either addresses or information to be stored.
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A channel 7 punch indicates that the adjacent column and the following column are to be interpreted as an
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address specifiying the location in which the information of the following two columns is to be stored.
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The tape leader and trailer of RIM format tape must be punched in channel 8 only (octal 200).
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</p>
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</td>
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</tr>
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<tr>
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<td class="left">
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<img src="bin_tape.png">
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</td>
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<td class="left">
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<h3>BIN (Binary) Format</h3>
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<p>
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BIN format tape is similar to RIM format except that only the first address of consecutive locations is
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specified.
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An address is designated by a channel 7 punch, and information following an address is stored in sequential
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locations after the designated address until another location is specified as an origin.
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The tape leader and trailer of BIN format tape must be punched in channel 8 (octal 200) only.
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Field setting is designated by channel 8 and 7 punch plus a three digit field number in channels 4 through 6.
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</p>
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<p>
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The last two columns of a BIN format tape contain a checksum.
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The checksum is the sum (modulo 7777) of all preceding columns not containing a channel 8 punch
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(the field settings are not included in the checksum).
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When the BIN loader halts the PDP-8 with AC ≠ 0, then a checksum error occured while loading the tape.
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</p>
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</td>
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</tr>
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</table>
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</body>
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</html>
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