Groups > alt.folklore.computers > #219136

Re: bootstrap, was What is the oldest computer that could be used today for real work?

From	Anne & Lynn Wheeler <lynn@garlic.com>
Newsgroups	alt.folklore.computers
Subject	Re: bootstrap, was What is the oldest computer that could be used today for real work?
Date	2021-09-29 17:16 -1000
Organization	Wheeler&Wheeler
Message-ID	<87fstm21nk.fsf@localhost> (permalink)
References	<sh246e$9kp$1@theuse.news.theuse.net> <qglskgp59l17f0jo3eb6i016iq68har3ul@4ax.com> <874ka9p19x.fsf@bogus.nodomain.nowhere> <61531446.14588537@news.dslextreme.com> <sj2o7u$2f2l$1@gal.iecc.com>

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John Levine <johnl@taugh.com> writes:
> Sounds like S/360.  You set the device number of the IPL (initial
> program load) device in the switches and pressed the IPL button.  That
> ran a fixed one instruction channel program pretending to be at
> location 0, that read 24 bytes into 0-23, then executed whatever was
> read into locaion 8, typically another read command to read a disk or
> tape block with real bootstrap, then started the computer by restoring
> the status word at location 0 which runs the bootstrap just read in to
> start up the computer.

old post to ibm-main & alt.folklore.computers
http://www.garlic.com/~lynn/2007f.html#1
discussing 360 "3card loader" and BPS (card) loader ... also
references "How to cread CDROM IPL Images" for use with hercules
(mainframe emulator)
https://www.cbttape.org/~jjaeger/cdrom.html

following is from old assemble program ... it can bootstrap load the
assembler program it is included in ... the "xxx"s originally were
EBCDIC HEX

*********************************************************************** 00046000
*                                                                     * 00047000
*        TWO-CARD ABSOLUTE LOADER -- THE FOLLOWING ARE SELF-LOADING   * 00048000
*        IPL-ABLE CARDS THAT LOAD A CHANNEL PROGRAM WHICH FUNCTIONS   * 00049000
*        AS AN ABSOLUTE TXT CARD LOADER, EXECUTING AS A COMMAND CHAIN * 00050000
*        FROM THE INITIAL IPL READ.  IF PUNCHED BEFORE ANY ASSEMBLED  * 00051000
*        INSTRUCTIONS OR DATA, THE TEXT FILE THE ASSEMBLER PRODUCES   * 00052000
*        MAY BE CONVERTED INTO A SELF-LOADING DECK BY USING AN EDITOR * 00053000
*        TO DELETE ANY RECORDS PRECEDING THE TWO LOADER CARDS, WHICH  * 00054000
*        IMMEDIATELY PRECEDE THE FIRST TXT RECORD IN THE TEXT OUTPUT. * 00055000
*                                                                     * 00056000
*        NO CONSTANTS MAY BE ASSEMBLED IN THE ABSOLUTE ADDRESS RANGE  * 00057000
*        X'10' TO X'43', AS THEIR LOADING WOULD OVERWRITE THE LOADER  * 00058000
*        AND CAUSE IPL FAILURES.  THE LOADER OPERATION IS TERMINATED  * 00059000
*        BY LOADING AN ORDINARY NOP CCW AT LOCATION X'40'.  WHEN THE  * 00060000
*        ASSEMBLY BEGINS WITH A 'LABEL START 0' STATEMENT, THIS COULD * 00061000
*        BE ACCOMPLISHED BY INSERTING THE SEQUENCE:                   * 00062000
*                                                                     * 00063000
*                  ORG   LABEL+X'40'                                  * 00064000
*                  CCW   X'03',0,X'20',1                              * 00065000
*                                                                     * 00066000
*        FOLLOWING THE FINAL STATEMENT SPECIFYING ASSEMBLED OUTPUT TO * 00067000
*        BE LOADED.                                                   * 00068000
*                                                                     * 00069000
*                                                                     * 00071000
         PUNCH 'xxxxxxxxxxxxxxxxxxxxxxxxFIRST LOADABLE RECORD' CARD 1 * 00072000
         PUNCH 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' CARD 2 * 00073000
*                                                                     * 00074000
*********************************************************************** 00075000

recent post (to facebook) about early CP67, including discussion of
(assemble output) BPS "TXT" deck loading
http://www.garlic.com/~lynn/2021i.html#61


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