Re: First boot on PDP-11/23! - VMS

This is a discussion on Re: First boot on PDP-11/23! - VMS ; > From: "Meat Loaf" > Subject: Re: First boot on PDP-11/23! > Date: Sun, 01 May 2005 22:35:10 -0500 > To: info-pdp11@village.org > > bill@cs.uofs.edu (Bill Gunshannon) wrote in > > news:3dbu28F6sp4bsU1@individual.net: > > > > > In article , ...

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Thread: Re: First boot on PDP-11/23!

  1. Re: First boot on PDP-11/23!

    > From: "Meat Loaf"
    > Subject: Re: First boot on PDP-11/23!
    > Date: Sun, 01 May 2005 22:35:10 -0500
    > To: info-pdp11@village.org
    > > bill@cs.uofs.edu (Bill Gunshannon) wrote in
    > > news:3dbu28F6sp4bsU1@individual.net:
    > >
    > > > In article ,
    > > > William Korvine writes:
    > > >> Powered 'er up and got "28/START?"!!!
    > > >> Yay, I made it to the console debugger!
    > > >>
    > > >> Help: The "28" means 28K detected. I have 256K installed. I have a
    > > >> memory problem. How can I proceed?
    > > >
    > > > I think 28KW is all the startup ever detects.
    > > >
    > > > bill
    > > >

    > >
    > > Ok, I used ODT and poked values into n00004 where 0<=n<=7 and read
    > > the correct values back. I conclude that despite the value at the
    > > START prompt, I actually have 256K of working RAM.
    > >
    > > I'm going to end my works here for a little while. For those who have
    > > been following my travails, thanks for your attention and aid.
    > >
    > > I now have a working CPU with 256kb of RAM and a working 4-port
    > > serial card. This is everything I planned to accomplish at this stage.
    > >
    > > I have no storage devices, so there's not much more I can do until I
    > > get them. Since I have no room for RL or RX drives, I must wait for a
    > > SCSI interface to become available or build an emulator device. I've
    > > seen the plans for the emulator boards such as at
    > > http://www.geocities.com/saipan59/dec/rxv11_emu.html
    > > and doubt I will attempt it. Besides, if I wanted an emulated PDP, I
    > > would have downloaded one.
    > >
    > > I still have the RLV11 boards, although the capacitors on one of them
    > > are physically damaged and need replacing. I will probably attempt
    > > that eventually just to preserve the boards. And who knows, I might
    > > have room for RLs some day.
    > >
    > > Last post for a little while. Thanks, and take care.
    > >
    > > .wk.

    >
    > What you will find is that the PDP-11's basically use 28K for memory
    > and 4K to address what they call the I/O page. Unlike the Intel type
    > processor that has an input and output instruction the PDP's (and
    > VAX's) used memory mapped I/O. Also to use memory greater than 28K it
    > is done with memory management hardware that rearranges 4k pages to
    > point to different areas of physical memory. The PDP-11/23 also has a
    > memory management seperation for kernel and user mode operation. This
    > allowed some added protection, such as a user mode "HALT" instruction
    > would not execute instead it would cause an illegal instruction TRAP to
    > occur.


    Something that can be very confusing on an 11/23: Console ODT does
    not have the capability of addressing the full 22-bit memory address space.

    Top of 16-bit memory space is 160000 - 2
    Top of 18-bit memory space is 760000 - 2
    Top of 22-bit memory space is 17760000 - 2

    If you type addresses greater than 777776 to Console ODT, they will be
    wrapped in the 18-bit space.

    carl
    --
    carl lowenstein marine physical lab u.c. san diego
    clowenst@ucsd.edu
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  2. Re: First boot on PDP-11/23!

    Carl Lowenstein wrote in
    news:200505021807.j42I7CH11861@opihi.ucsd.edu:

    >> From: "Meat Loaf"
    >> Subject: Re: First boot on PDP-11/23!
    >> Date: Sun, 01 May 2005 22:35:10 -0500
    >> To: info-pdp11@village.org
    >> > bill@cs.uofs.edu (Bill Gunshannon) wrote in
    >> > news:3dbu28F6sp4bsU1@individual.net:
    >> >
    >> > > In article ,
    >> > > William Korvine writes:
    >> > >> Powered 'er up and got "28/START?"!!!
    >> > >> Yay, I made it to the console debugger!
    >> > >>
    >> > >> Help: The "28" means 28K detected. I have 256K installed. I have
    >> > >> a memory problem. How can I proceed?
    >> > >
    >> > > I think 28KW is all the startup ever detects.
    >> > >
    >> > > bill
    >> > >
    >> >
    >> > Ok, I used ODT and poked values into n00004 where 0<=n<=7 and read
    >> > the correct values back. I conclude that despite the value at the
    >> > START prompt, I actually have 256K of working RAM.
    >> >
    >> > I'm going to end my works here for a little while. For those who
    >> > have been following my travails, thanks for your attention and aid.
    >> >
    >> > I now have a working CPU with 256kb of RAM and a working 4-port
    >> > serial card. This is everything I planned to accomplish at this
    >> > stage.
    >> >
    >> > I have no storage devices, so there's not much more I can do until
    >> > I get them. Since I have no room for RL or RX drives, I must wait
    >> > for a SCSI interface to become available or build an emulator
    >> > device. I've seen the plans for the emulator boards such as at
    >> > http://www.geocities.com/saipan59/dec/rxv11_emu.html
    >> > and doubt I will attempt it. Besides, if I wanted an emulated PDP,
    >> > I would have downloaded one.
    >> >
    >> > I still have the RLV11 boards, although the capacitors on one of
    >> > them are physically damaged and need replacing. I will probably
    >> > attempt that eventually just to preserve the boards. And who knows,
    >> > I might have room for RLs some day.
    >> >
    >> > Last post for a little while. Thanks, and take care.
    >> >
    >> > .wk.

    >>
    >> What you will find is that the PDP-11's basically use 28K for memory
    >> and 4K to address what they call the I/O page. Unlike the Intel type
    >> processor that has an input and output instruction the PDP's (and
    >> VAX's) used memory mapped I/O. Also to use memory greater than 28K
    >> it is done with memory management hardware that rearranges 4k pages
    >> to point to different areas of physical memory. The PDP-11/23 also
    >> has a memory management seperation for kernel and user mode
    >> operation. This allowed some added protection, such as a user mode
    >> "HALT" instruction would not execute instead it would cause an
    >> illegal instruction TRAP to occur.

    >
    > Something that can be very confusing on an 11/23: Console ODT does
    > not have the capability of addressing the full 22-bit memory address
    > space.
    >
    > Top of 16-bit memory space is 160000 - 2
    > Top of 18-bit memory space is 760000 - 2
    > Top of 22-bit memory space is 17760000 - 2
    >
    > If you type addresses greater than 777776 to Console ODT, they will be
    > wrapped in the 18-bit space.
    >
    > carl


    I didn't know that. I'm not too worried because I only have an 18-bit
    address space anyway (I'm pretty sure).

    ..wk.

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