IBM Confidential: System/360 File Organization [video]
youtube.com
youtube.com
>Pearson LeRoy Wood, 81, passed away April 4, 2012. He was born May 12, 1930 in Detroit, MI. A graduate of Detroit Institute of Technology, Pearson served two years in the US Army. He was employed by IBM for 37 years. He was a member of Resurrection Lutheran Church and also The American Legion, Post 67, in Cary.
>Survivors are his wife, Elaine; two daughters, Diane Post (Barry) of Cary and Susan Scofield (Fred) of Wake Forest; five grandchildren; three great-grandchildren; five sisters and two brothers.
https://www.dignitymemorial.com/obituaries/cary-nc/pearson-w...
I've worked most of my career in developer relations at various Big Tech (advocate, evangelist, pre-sales, etc.) which in large part entails giving presentations explaining how a company's technology works to others. It makes me wonder if the couple official company videos I've made will be viewed in 70 years by that generation's techies.
When my Dad started in the late 60s IBM had discontinued the morning song tradition.
a webcast about the many great benefits of the novel DASD (direct access storage device) over ISAM (index sequential access)
aka disk and tape.
16mm film
Flipchart
impeccable presentation
thx for the time machine :-)
And they're not strictly just a disk. It's more like a complex multiplexing system for an array of disks. It has interesting capabilities like "channel programs" that persist to this day which allow you to send miniature programs to the disk controller to have it seek out the precise record you're looking for in one of several access modes.
IBM still provides almost the entirety of it's OS documentation online:
https://www.ibm.com/docs/en/zos-basic-skills?topic=set-what-...
A very long time ago, a guy I used to work with was porting a sales and stock control database he'd written on the Commodore PET to a PC. By then he had a 286 with a 20MB hard disk and 2MB of RAM to play with - whopping stuff! - but his original program would assemble up a query routine, and transmit it to the 6502 in the PET disk drives over HPIB. Then it would chunter away discovering the records it needed to construct a reply while the host computer could continue working as normal. It was absolutely genius stuff, and it made the whole system seem really responsive even though in reality it was pretty slow.
Chap needs to have his suit jacket fixed, though... that collar gap!
Tapes don't provide CKD interface and thus do not work with ISAM.
On Youtube there is no mention about the date.
OS/360 was announced in 1964 but it was first delivered more than a year later.
I doubt that such presentations were done about a product that no customers could use and which might still be changed until the first deliverable version.
So I believe that it is unlikely that this presentation was done earlier than 1965 and it is likely that it was not done before 1966. The first OS/360 versions were delivered in November/December 1965.
>This presentation is one of a series which is intended to present you the systems engineer and salesman some of the advantages of Systems/360
Sometimes companies used to hire artists to finish this kind of material, but usually engineers at that time were pretty much capable of drafting this kind of presentation on paper, just with rulers, compasses, and the ocasional template rule.
White collar professions used to be way more embodied in the real physic world. Kids were trained on caligraphy and basic drafting techniques since elementary school.
And since this was an internal IBM presentation for salesmen and engineers, the priority likely wouldn't've been on using a polished presenter, just making the information available.
Intel 8008 did not have anything original in its architecture, it was just a monolithic PMOS re-implementation of the CPU of the embedded computer designed for the serial terminal Datapoint 2200, which had been designed with TTL integrated circuits. All the decisions about sizes, e.g. 8-bit data and 14-bit addresses, had been done by Datapoint in 1970, not by Intel. Datapoint had chosen 8-bit bytes in order to support the recently standardized ASCII 7-bit character set (and the 8-bit IBM EBCDIC character set, if necessary), i.e. the character sets used by the computers to which such a serial terminal could be connected.
At the time when the first microprocessors were designed, during the first half of the seventies, the most important architectural influence on any new computer designs were the DEC PDP-11 minicomputers.
DEC PDP-11 used 8-bit bytes, which was a significant change from the previous DEC computers, most of which used word sizes that were a multiple of 6, like 12-bit, 18-bit or 36-bit.
DEC PDP-11 had transitioned to 8-bit bytes (in 1970) mainly due to the influence of IBM System/360. The standardization of the 7-bit ASCII code for characters, which could no longer fit inside 6-bit bytes, has contributed to this decision, but the standardization of ASCII was itself possible only because many computer vendors had already transitioned or decided to transition to 8-bit bytes, so they could store the new ASCII characters in their bytes.
After 1967, when ASCII was standardized in a form close to the present form, after which it was also taken into international standards by ISO and CCITT, all new computer instruction-set architectures were designed with 8-bit bytes.
Because eight rather than six bits are used to represent a. character, up to 256 possible characters could be represented in the Extended Binary Coded Decimal Interchange Code (EBCDIC) shown in Figure 7. Except for certain teleprocessing equipment, the code that makes use of characters is either EBCDIC or an eight-bit extension of a seven-bit code proposed by the International Standards Organization.
[1] http://bitsavers.informatik.uni-stuttgart.de/pdf/ibm/360/GC2...
The 7-bit ASCII code, with a few small differences from the current version, had been standardized in 1967 in USA as USAS X3.4-1967 and internationally as ISO 646.
No computer has ever been designed with 7-bit bytes, so all computers with 8-bit bytes, starting with IBM System/360, store the ASCII characters using an "8-bit extension of the 7-bit code".
Your document refers to this. The fact that ASCII has only 7 bits mattered only when the characters were sent over communication lines, when there was no need to transmit more than 7 data bits.
While in IBM systems EBCDIC was the primary character set and ASCII was used only for interchange with computing equipment made by other companies, in all the computers made by others the usage was reversed, ASCII extended to 8 bits was the primary character set, but EBCDIC was also supported for data interchange with IBM computers.
https://www.sensitiveresearch.com/Archive/CharCodeHist/X3.4-...
The 1963 ASCII version was very different from the 1967 and later versions, it did not even have lowercase letters.
ASCII-1963 must be considered as a different character set from the later ASCII versions. It had a very limited adoption as a method for storing text in computers, because in the beginning only IBM System/360 had 8-bit bytes, while most other computers still had 6-bit bytes, and System/360 used a much more complete character set, EBCDIC, for storing text.
Thus ASCII-1963 was used in the beginning only for communication on serial lines, e.g. in terminals like Teletype Model 33, where it had the advantage of having more control characters than 6-bit character sets, even if it had only about the same set of printable characters. For storage, an ASCII-1963 string would have been converted to some 6-bit character set, because there was no need to store control characters and the number of printable characters was less than 64.
In most contexts references to "ASCII" should be understood as referring only to the 1967 and later versions, which were complete 7-bit character sets and which were adopted as both US and international standards.
As for the name, the acronym ASCII comes from the 1963 version (American Standard Code for Information Interchange). Later in 1966, ASA became USASI, and the official name was changed to USASCII, with ASCII as an acceptable alternative abbreviation. Later still, in 1969, USASI changed its name once again to ANSI, and an attempt was made to rename it ANSCII, but this did not catch on, and ASCII returned as the official name.
As for this 8-bit extension (not seven-bit code proposed by the ISO), perhaps they were referring to ECMA-35, the first version of which was published in December 1971? Or perhaps other proposals mentioned in the brief history. Of course, it seems that ASCII - regardless of the version - served as the basis for these extensions.
https://ecma-international.org/wp-content/uploads/ECMA-35_1s...
Only after the number of printable characters had been greatly increased in 1967, making impossible the conversion to 6-bit character sets, and the new version was adopted not only in USA, but also internationally, by both ISO and CCITT, it became a necessity to have a byte size equal to or greater than 7 bits, in order to be able to store efficiently ASCII strings in computers.
From that moment on, the 8-bit byte size became a hard requirement for any new computer ISA, e.g. for DEC PDP-11, which was designed mostly during 1969 and it was launched in 1970.
IBM was ridiculously huge, both by actual IBM hardware, but also by clones, and manufacture of S/360-compatible systems. Even many wildly different computers often had third party interfaces to hook up S/360 channel devices, or controllers for the actual devices (it was common for channel devices to be linked like this: S/360 -> channel processor -> controller -> device-specific connections -> actual device).
Even the fact that we format code usually to 72 characters is related to 80-character standard S/360 punched card, where the remaining 8 characters were used for sorting/comment code, and why professional terminals (as opposed to things like 40 column mode on home computers) had 80 column displays.
Also, had ASCII been ready earlier, S/360 would have used ASCII as default encoding - IIRC S/360 team decided they can't wait for ASCII to be finalized and they needed to start design and making of various devices that would have to be encoding-aware, thus EBCDIC was born.
I didn't realize until recently how much IBM spend on S/360. It was simply astounding to me. In his Computer History Museum's oral history [0][1] Dr. Fred Brooks[2] says:
> I think was somewhere in the neighborhood of $400 million in 1964 dollars, which would be $4 billion today roughly
That checks out, from an inflation calculator perspective. That's wild. I had no idea money like that was being spent on platform development in the 60s.
[0] https://archive.computerhistory.org/resources/access/text/20...
Sorry, it was stronger than me \s