Path: csiph.com!eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail From: Anne & Lynn Wheeler Newsgroups: alt.folklore.computers Subject: Re: bootstrap, was What is the oldest computer that could be used today for real work? Date: Wed, 29 Sep 2021 17:16:47 -1000 Organization: Wheeler&Wheeler Lines: 58 Message-ID: <87fstm21nk.fsf@localhost> References: <874ka9p19x.fsf@bogus.nodomain.nowhere> <61531446.14588537@news.dslextreme.com> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: reader02.eternal-september.org; posting-host="ac177fc69d0bde9c3d6fe6762af1d29b"; logging-data="25792"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+T8jPyMSgwLILUBIWQJZOpaXsx84xTTqg=" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) Cancel-Lock: sha1:K+dBYhjrSlOR5pCu6Dx1rrFidGM= sha1:elUR5fxxHWDV4yyI7vALmbvNCd0= Xref: csiph.com alt.folklore.computers:219136 John Levine 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 -- virtualization experience starting Jan1968, online at home since Mar1970