• segments and architectural experimentation (was Re: segments, was Self-

    From Kragen Javier Sitaker@3:633/10 to All on Friday, September 11, 2026 08:13:05
    Subject: segments and architectural experimentation (was Re: segments, was Self-hosting and the 6502)

    scott@slp53.sl.home (Scott Lurndal) writes:
    When I started at Burroughs, they had just started a project
    to increase amount of memory that could be accessed by
    an application on the medium systems (B3500) line. The
    B3500 had a flat one million digit address space and
    could run in ?control state? or ?normal state?. When the
    base register had the value zero, the processor ran in
    control state and privileged instructions were available,
    otherwise the processor was is normal state and the
    1md address space started at the privileged base register and
    ended at the privileged limit register.

    That?s an interesting approach! I had no idea how the Medium Systems
    line worked.

    You?d think you?d see a lot of experimentation around things like this
    nowadays that you can get your own open-source chip design fabbed
    through Tiny Tapeout for US$300, including in IHP?s 350GHz 130nm SiGe
    BiCMOS process. (Not 350MHz; fT is 350GHz.)

    Without Tiny Tapeout, IHP?s MPW price for that ?SG13G2? process is
    ?7300/mmę with a minimum of 0.8mmę, which I find a rather daunting
    pricetag for something that probably won?t work the first time. As I understand it, that kind of thing is what sunk Chuck Moore?s chip design efforts at iTV in the 90s: they didn?t have enough capital to iterate
    fast enough with MPW runs through MOSIS to ever ship a working chip.

    New approaches to protection seem like an especially promising area as
    we smash headfirst into the ?vulnpocalypse? and AI generates exploits
    for the swiss-cheese computer systems the whole internet is built on.

    Kragen

    --- PyGate Linux v1.5.19
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From Peter Flass@3:633/10 to All on Friday, September 11, 2026 07:29:31
    Subject: Re: segments and architectural experimentation (was Re: segments, was Self-hosting and the 6502)

    On 9/11/26 04:13, Kragen Javier Sitaker wrote:
    scott@slp53.sl.home (Scott Lurndal) writes:
    When I started at Burroughs, they had just started a project
    to increase amount of memory that could be accessed by
    an application on the medium systems (B3500) line. The
    B3500 had a flat one million digit address space and
    could run in ?control state? or ?normal state?. When the
    base register had the value zero, the processor ran in
    control state and privileged instructions were available,
    otherwise the processor was is normal state and the
    1md address space started at the privileged base register and
    ended at the privileged limit register.

    That?s an interesting approach! I had no idea how the Medium Systems
    line worked.

    This is not an unusual approach. Many systems of the time used the same,
    I know of the GE 400 line, and I believe the CDC 6x00.>

    --- PyGate Linux v1.5.19
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From john larkin@3:633/10 to All on Friday, September 11, 2026 07:55:05
    Subject: Re: segments and architectural experimentation (was Re: segments, was Self-hosting and the 6502)

    On Fri, 11 Sep 2026 08:13:05 -0300, Kragen Javier Sitaker <kragen@canonical.org> wrote:

    scott@slp53.sl.home (Scott Lurndal) writes:
    When I started at Burroughs, they had just started a project
    to increase amount of memory that could be accessed by
    an application on the medium systems (B3500) line. The
    B3500 had a flat one million digit address space and
    could run in ?control state? or ?normal state?. When the
    base register had the value zero, the processor ran in
    control state and privileged instructions were available,
    otherwise the processor was is normal state and the
    1md address space started at the privileged base register and
    ended at the privileged limit register.

    That?s an interesting approach! I had no idea how the Medium Systems
    line worked.

    You?d think you?d see a lot of experimentation around things like this >nowadays that you can get your own open-source chip design fabbed
    through Tiny Tapeout for US$300, including in IHP?s 350GHz 130nm SiGe
    BiCMOS process. (Not 350MHz; fT is 350GHz.)

    Without Tiny Tapeout, IHP?s MPW price for that ?SG13G2? process is
    ?7300/mm? with a minimum of 0.8mm?, which I find a rather daunting
    pricetag for something that probably won?t work the first time. As I >understand it, that kind of thing is what sunk Chuck Moore?s chip design >efforts at iTV in the 90s: they didn?t have enough capital to iterate
    fast enough with MPW runs through MOSIS to ever ship a working chip.

    New approaches to protection seem like an especially promising area as
    we smash headfirst into the ?vulnpocalypse? and AI generates exploits
    for the swiss-cheese computer systems the whole internet is built on.

    Kragen

    I was talking to a college student yesterday who turns out to be an
    opamp freak. We were arguing about what's our favorite gumdrop
    higher-voltage opamp. I like OPA197 and he likes some OPA2xxx and
    beats me on slew rate. Punk kid.

    He has designed an IC CMOS opamp and is having some fabbed. Even kids
    can do that nowadays.


    John Larkin
    Highland Tech Glen Canyon Design Center
    Lunatic Fringe Electronics

    --- PyGate Linux v1.5.19
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From David Schultz@3:633/10 to All on Friday, September 11, 2026 13:06:38
    Subject: Re: segments and architectural experimentation (was Re: segments, was Self-hosting and the 6502)

    On 9/11/26 9:55 AM, john larkin wrote:
    He has designed an IC CMOS opamp and is having some fabbed. Even kids
    can do that nowadays.

    They could do it in the 90's. You couldn't fit a lot onto a MOSIS
    Tinychip in 2 micron but you could get stuff done. Without paying for it yourself as the professor usually had a budget for that sort of thing.

    --
    https://davesrocketworks.com
    David Schultz
    "It's just this little chromium switch here..."

    --- PyGate Linux v1.5.19
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
  • From someone@3:633/10 to All on Monday, September 14, 2026 16:45:02
    Subject: Re: segments and architectural experimentation (was Re: segments, was Self-hosting and the 6502)

    A one million bit address space means 2^20 or 20 bits. Partitioning memory into blocks has been around since the days of magnetic core memory. All those old machines used base registers, offset, registers, index registers or some other means to form addresses. It certainly simplified the opcode designation and address formation for memory access. Looks like it later eveloved into cache memory speedup which was premised on the assumption the code was working on data in reasonabe proximity in the memory. Magnetic core was slow, dynamic RAM was quick, and they were just getting used to the idea of static versus "volatile" memory.

    --
    For full context, visit https://www.electrondepot.com/electrodesign/segments-and-architectural-experimentation-was-re-segments-4410551-.htm


    --- PyGate Linux v1.5.19
    * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)