5 ms·

Funny thing about that. At Alpha Microsystems, about 1982, I was in charge of the diagnostic programming group. At that time failing memory boards were expensi

Funny thing about that. At Alpha Microsystems, about 1982, I was in charge of the diagnostic programming group. At that time failing memory boards were expensive and customers would not be happy with such components. I wrote a memory testing diagnostic that was based on knowing exactly how addresses were mapped to cell locations so I could try to provoke such failures. Chip manufacturers were aware of this problem which is why they scrambled the addresses. Potential vendors, Motorola et al, were required to provide mapping information before we would consider their chips. Now I'm curious to know what such mapping looks like with modern memory chips.

classichasclass 5y ago
Not related to article: would love to hear about your time at Alpha Microsystems. See https://ampm.floodgap.com/ https://ampm.floodgap.com/ (hosted on an Alpha Micro Eagle 300).
- zanethomas 5y ago
  Here's a bit of history ... I think the lead up helps to understand what I did first at AM. I'll send you an email with more info later. 1976-1985 My first job was at Basic Four Corporation. I got in as a test technician, assembling small refrigerator-sized mini-computers, giving them their first tests and swapping components until they passed. I soon learned how to use the machine-language assembler and started writing small programs to help me determine which components were failing without swapping and hoping. Within a few months I was testing more than 2x the number of machines the other techs were testing. Management noticed and soon the other techs were getting up to speed. At this point management pretty-much turned me loose. I moved up to diagnosing and repairing failed components (8"x11" pcbs). My understanding of programming and digital circuits allowed me to write small programs that could be used to "light up" specific circuits on the board making it easy to poke around with a scope to see where things went wrong. Again this was a huge productivity boost and the technique was propagated to other techs. A couple years later I went back for a while part-time as a consultant and wrote my first DSL for techs to use. Next I talked my way into the firmware development group and worked on firmware for tape, disk and other devices. This is the period of time when microprocessors were being incorporated into everything and my experience with the Micro-68 put me in a good position to participate. I also got to write microcode for a 2901-based cpu that was in development. And then, somehow, perhaps at a user's group, I learned about Alpha Microsystems. When I first visited Alpha Microsystems their idea of "burning in" pcbs consisted of putting them in a powered backplane, in a wooden box, with a lightbulb, where they sat for some period of time. Basic Four had serious testing which included putting entire computers into temperature-cycling ovens where they ran tests for 24 hours. That knocked out a pretty high percentage of boards. After I told them what they were missing Alpha Microsystems hired me to improve their process. For the next several years I participated in creating the flow of production and testing. A department evolved to handle the hardware side of things and I became head of a diagnostic programming department which grew to, variously, between 6 and 10 programmers. After that department was functioning and had someone who could step up I transferred into the operating systems group. I was one of only three people allowed to work on the operating system code, let alone even see it since it was held as a trade secret. During my last year at Alpha Microsystems a brilliant programmer I had hired introduced me to the then just-released Structure And Interpretation Of Computer Programming, a new textbook for students at MIT. That book's use of the language Scheme introduced me to first-class functions, closures, and many other concepts which found their way into popular programming languages decades later. The SICP had all the information one needed to create a Scheme interpreter. I wrote one using 68000 assembler so I could run the sample code.
  - kawsper 5y ago
    Wauw, amazing! Thank you so much for sharing your story!
    - zanethomas 5y ago
      ha, thanks! i love programming so much i've never quit taught fullstack at ucla BC (before covid) did a large frontend project with vue the past year i'll die with a keyboard under my fingers!
- kingcharles 5y ago
  "There are no subdirectories in AMOS." Yowch. Like PC-DOS 1.0 all over again.
  - zanethomas 5y ago
    Technically that's correct, but a bit misleading. You need to bear in mind how limited disk storage was in the 70s and early 80s. When I got to AM systems were booting from 8" floppy disks. That gave you about 500kb, iirc. The file system had "directories" in this form: [nnn,nnn] Where, again iirc, nnn was 8 bits, so 11 111 111, 377 for example. Only 16 bits were required to specify the location of a file. Filenames, btw, were six characters.
    - ZWoz 5y ago
      Your description ([nnn,nnn]) reminded me TOPS-10 and indeed, that AMOS link mentions this: "The similarities with DEC's operating systems, particularly TOPS-10, were not lost on Digital Equipment Corporation". So, that file hierarchy model is even earlier, than 70s and 80s. Wikipedia says that TOPS-10 was released in 1967 (back then different name, renamed in 1970). DECsystem-10 was anyway pretty different hardware from modern computer, running from tapes and so on. Sorry for that offtopic rambling, I am little bit enthusiastic every time, if I see something TOPS10 related.
      - zanethomas 5y ago
        iirc (so many years) AMOS was based on DEC's RSTS hence a lawsuit which AM eventually won the western digital chipset that powered the first am systems was a five-chip 40-pin set connected by a private cmos bus ... probing with a scope was amusing the instruction set was basically identical to the pdp-11
    - kingcharles 5y ago
      That's a good point. I don't really remember bothering with directories on any of my 360kb 5.25" floppies in the 80s. When you can only fit 10 files on a disc a hierarchy is usually unwarranted. You hierarchy is those little plastic dividers in your floppy disc storage box.

classichasclass 5y ago

Not related to article: would love to hear about your time at Alpha Microsystems. See https://ampm.floodgap.com/ https://ampm.floodgap.com/ (hosted on an Alpha Micro Eagle 300).

zanethomas 5y ago
Here's a bit of history ... I think the lead up helps to understand what I did first at AM. I'll send you an email with more info later. 1976-1985 My first job was at Basic Four Corporation. I got in as a test technician, assembling small refrigerator-sized mini-computers, giving them their first tests and swapping components until they passed. I soon learned how to use the machine-language assembler and started writing small programs to help me determine which components were failing without swapping and hoping. Within a few months I was testing more than 2x the number of machines the other techs were testing. Management noticed and soon the other techs were getting up to speed. At this point management pretty-much turned me loose. I moved up to diagnosing and repairing failed components (8"x11" pcbs). My understanding of programming and digital circuits allowed me to write small programs that could be used to "light up" specific circuits on the board making it easy to poke around with a scope to see where things went wrong. Again this was a huge productivity boost and the technique was propagated to other techs. A couple years later I went back for a while part-time as a consultant and wrote my first DSL for techs to use. Next I talked my way into the firmware development group and worked on firmware for tape, disk and other devices. This is the period of time when microprocessors were being incorporated into everything and my experience with the Micro-68 put me in a good position to participate. I also got to write microcode for a 2901-based cpu that was in development. And then, somehow, perhaps at a user's group, I learned about Alpha Microsystems. When I first visited Alpha Microsystems their idea of "burning in" pcbs consisted of putting them in a powered backplane, in a wooden box, with a lightbulb, where they sat for some period of time. Basic Four had serious testing which included putting entire computers into temperature-cycling ovens where they ran tests for 24 hours. That knocked out a pretty high percentage of boards. After I told them what they were missing Alpha Microsystems hired me to improve their process. For the next several years I participated in creating the flow of production and testing. A department evolved to handle the hardware side of things and I became head of a diagnostic programming department which grew to, variously, between 6 and 10 programmers. After that department was functioning and had someone who could step up I transferred into the operating systems group. I was one of only three people allowed to work on the operating system code, let alone even see it since it was held as a trade secret. During my last year at Alpha Microsystems a brilliant programmer I had hired introduced me to the then just-released Structure And Interpretation Of Computer Programming, a new textbook for students at MIT. That book's use of the language Scheme introduced me to first-class functions, closures, and many other concepts which found their way into popular programming languages decades later. The SICP had all the information one needed to create a Scheme interpreter. I wrote one using 68000 assembler so I could run the sample code.
- kawsper 5y ago
  Wauw, amazing! Thank you so much for sharing your story!
  - zanethomas 5y ago
    ha, thanks! i love programming so much i've never quit taught fullstack at ucla BC (before covid) did a large frontend project with vue the past year i'll die with a keyboard under my fingers!
kingcharles 5y ago
"There are no subdirectories in AMOS." Yowch. Like PC-DOS 1.0 all over again.
- zanethomas 5y ago
  Technically that's correct, but a bit misleading. You need to bear in mind how limited disk storage was in the 70s and early 80s. When I got to AM systems were booting from 8" floppy disks. That gave you about 500kb, iirc. The file system had "directories" in this form: [nnn,nnn] Where, again iirc, nnn was 8 bits, so 11 111 111, 377 for example. Only 16 bits were required to specify the location of a file. Filenames, btw, were six characters.
  - ZWoz 5y ago
    Your description ([nnn,nnn]) reminded me TOPS-10 and indeed, that AMOS link mentions this: "The similarities with DEC's operating systems, particularly TOPS-10, were not lost on Digital Equipment Corporation". So, that file hierarchy model is even earlier, than 70s and 80s. Wikipedia says that TOPS-10 was released in 1967 (back then different name, renamed in 1970). DECsystem-10 was anyway pretty different hardware from modern computer, running from tapes and so on. Sorry for that offtopic rambling, I am little bit enthusiastic every time, if I see something TOPS10 related.
    - zanethomas 5y ago
      iirc (so many years) AMOS was based on DEC's RSTS hence a lawsuit which AM eventually won the western digital chipset that powered the first am systems was a five-chip 40-pin set connected by a private cmos bus ... probing with a scope was amusing the instruction set was basically identical to the pdp-11
  - kingcharles 5y ago
    That's a good point. I don't really remember bothering with directories on any of my 360kb 5.25" floppies in the 80s. When you can only fit 10 files on a disc a hierarchy is usually unwarranted. You hierarchy is those little plastic dividers in your floppy disc storage box.