Minimalist CP/M system? - CP/M

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  1. Minimalist CP/M system?

    Hello!
    As is usual for this time period I have a new project taking shape.
    (Or it should be...)

    What would be considered a simple CP/M-80 system? Memory, and
    associated peripherals, plus disk drive as one of the peripherals.
    ---
    Gregg drwho8@att.net

  2. Re: Minimalist CP/M system?

    On Mon, 16 Jun 2008 02:44:19 GMT, Gregg C Levine
    wrote:

    >Hello!
    >As is usual for this time period I have a new project taking shape.
    >(Or it should be...)
    >
    >What would be considered a simple CP/M-80 system? Memory, and
    >associated peripherals, plus disk drive as one of the peripherals.
    >---
    >Gregg drwho8@att.net


    What do you consider minimalist?

    Enough ram for cpm 16k for 1.4, 20k for 2.2.
    console *can be anything* common was serial port.
    Punch, reader, list are optional.
    mass storage.

    Allison

  3. Re: Minimalist CP/M system?

    On Jun 15, 9:44*pm, Gregg C Levine wrote:
    > Hello!
    > As is usual for this time period I have a new project taking shape.
    > (Or it should be...)
    >
    > What would be considered a simple CP/M-80 system? Memory, and
    > associated peripherals, plus disk drive as one of the peripherals.
    > ---
    > Gregg drw...@att.net


    I think mine's pretty minimal... aside from the 9918 graphics
    controller and IDE hard drive.

    Z80 CPU
    64k RAM (has my monitor eprom on it)
    2 x serial ports (1 to PC as serial console)
    1 x FDC (to single Shugart 850)

    JS

  4. Re: Minimalist CP/M system?

    MdntTrain wrote:
    (snip on minimalist CP/M system)

    > I think mine's pretty minimal... aside from the 9918 graphics
    > controller and IDE hard drive.


    > Z80 CPU
    > 64k RAM (has my monitor eprom on it)
    > 2 x serial ports (1 to PC as serial console)
    > 1 x FDC (to single Shugart 850)


    How about an ethernet port, no serial ports
    (use telnet), no disks (use NFS). You might want
    a larger RAM and/or ROM for the TCP code, and an
    ethernet interface with local RAM buffer.

    -- glen


  5. Re: Minimalist CP/M system?

    On 2008-06-19, glen herrmannsfeldt wrote:
    > How about an ethernet port, no serial ports
    > (use telnet), no disks (use NFS). You might want
    > a larger RAM and/or ROM for the TCP code, and an
    > ethernet interface with local RAM buffer.


    Well, in that case, all you'd need is an eZ80, a PHY, and a TCP stack.
    Might as well hang an SD card socket of the SPI port while you're at;
    they're cheap.
    --
    roger ivie
    rivie@ridgenet.net

  6. Re: Minimalist CP/M system?

    On Jun 16, 6:44 am, Gregg C Levine wrote:

    > What would be considered a simple CP/M-80 system?


    Look at the Altera FPGA, DE-1 board (~150$) as example. There is T80
    (a Z80 softcore)
    and some projects based around this processor: Yamaha MSX, Sinclair
    and Vector-06C
    computers.

    http://university.altera.com/materia...du-boards.html

    http://www.opencores.org/projects.cgi/web/t80/overview

    http://zxgate.sourceforge.net/

    http://en.wikipedia.org/wiki/1chipMSX

    http://code.google.com/p/vector06cc/

    --
    -=AV=-

  7. Re: Minimalist CP/M system?

    Hi!

    http://lh3.ggpht.com/svofski/SFohN0g...s/IMG_2451.JPG

    (one long URL)

    You could see a Vector-06C CP/M running on the Altera DE-1
    reading Robotron 1715/W diskette image.
    The Altera DE-1 is left bottom.

    --
    -=AV=-

  8. Re: Minimalist CP/M system?

    On Mon, 16 Jun 2008 02:44:19 GMT, Gregg C Levine
    wrote:

    >Hello!
    >As is usual for this time period I have a new project taking shape.
    >(Or it should be...)
    >
    >What would be considered a simple CP/M-80 system? Memory, and
    >associated peripherals, plus disk drive as one of the peripherals.
    >---
    >Gregg drwho8@att.net


    OK, alternate aproach.

    8085, 32k ram, 32k rom a few gates to force the rom and ram
    addess to swap for boot. The 8085 does bit bang serial using the
    SID, SOD line total parts count really small. Rom has enough space
    24k for a few small applications (as romdisk).

    Adding a disk drive (floppy, IDE or CF) would emply the unused
    IO addressing. Minimalist designs could be as few as maybe 2
    TTL ICs plus a CF.

    With variation it would be fairly easy to make tha into a full 64k ram
    with a larger (megabyte sized) rom that is bank switched for a
    significant sized R/W ramdisk and romdisk and can still support
    a array of IO added later.

    It could be Z80 but you will need at least one IO port (1bit for input
    and one for output) to do bit banged serial.

    Allison




  9. Re: Minimalist CP/M system?

    no.spam@no.uce.bellatlantic.net wrote:

    > OK, alternate aproach.


    > 8085, 32k ram, 32k rom a few gates to force the rom and ram
    > addess to swap for boot. The 8085 does bit bang serial using the
    > SID, SOD line total parts count really small. Rom has enough space
    > 24k for a few small applications (as romdisk).


    I have one of those! I wired it up so that it would run
    the SDK-85 ROM monitor, including the serial port I/O.
    (80C85, high address latch, address/data bus buffer,
    and TTL<-->RS232 buffers.)

    I got tired of running at 110 baud, so I changed the loops
    to run at 9600.

    How hard is it to run CP/M completely from ROM?

    -- glen


  10. Re: Minimalist CP/M system?

    glen herrmannsfeldt wrote:
    >

    .... snip ...
    >
    > How hard is it to run CP/M completely from ROM?


    Hard. CP/M has data areas mixed in with its code. The replacement
    for CP/M 2.2 (dospls25 and dosplsor, both .zip) is better
    organized, but still has some slight problems to do with errors as
    I recall (I wrote it 20 years ago). You can get those zip files
    at:



    --
    [mail]: Chuck F (cbfalconer at maineline dot net)
    [page]:
    Try the download section.

    ** Posted from http://www.teranews.com **

  11. Re: Minimalist CP/M system?

    On Fri, 20 Jun 2008 00:12:47 -0800, glen herrmannsfeldt
    wrote:

    >no.spam@no.uce.bellatlantic.net wrote:
    >
    >> OK, alternate aproach.

    >
    >> 8085, 32k ram, 32k rom a few gates to force the rom and ram
    >> addess to swap for boot. The 8085 does bit bang serial using the
    >> SID, SOD line total parts count really small. Rom has enough space
    >> 24k for a few small applications (as romdisk).

    >
    >I have one of those! I wired it up so that it would run
    >the SDK-85 ROM monitor, including the serial port I/O.
    >(80C85, high address latch, address/data bus buffer,
    >and TTL<-->RS232 buffers.)
    >
    >I got tired of running at 110 baud, so I changed the loops
    >to run at 9600.
    >
    >How hard is it to run CP/M completely from ROM?


    CP/M2 has data areas in the code segment. They are easy
    to isolate in the source if you willing to reassemble.

    However...
    Then you need to figure where to put the data areas and under the
    rom in high ram is subject to invasion by things that load high in ram
    like DDT. You also have to put the buffers in the bios somethere
    too.

    Using 32k rams, 32k roms it's easy to invert A15 at startup to put
    rom at 0000 copy to ram then flip the bit (Uses 1 xor gate).

    Allison


    >
    >-- glen



  12. Re: Minimalist CP/M system?

    no.spam@no.uce.bellatlantic.net wrote:

    (snip, I wrote)
    >>How hard is it to run CP/M completely from ROM?


    > CP/M2 has data areas in the code segment. They are easy
    > to isolate in the source if you willing to reassemble.


    > However...
    > Then you need to figure where to put the data areas and under the
    > rom in high ram is subject to invasion by things that load high in ram
    > like DDT. You also have to put the buffers in the bios somethere
    > too.


    > Using 32k rams, 32k roms it's easy to invert A15 at startup to put
    > rom at 0000 copy to ram then flip the bit (Uses 1 xor gate).


    It would be nice in ROM where you don't have to worry
    about writing over it. Otherwise, instead of just one
    gate arrange so that initially the ROM is read and RAM is
    written, copy the whole ROM over, then switch to RAM only.

    That will take more than one XOR gate (and a latch for
    its input) but maybe not much more.

    -- glen


  13. Re: Minimalist CP/M system?

    CBFalconer wrote:
    > glen herrmannsfeldt wrote:
    >
    > ... snip ...
    >
    >> How hard is it to run CP/M completely from ROM?

    >
    > Hard. CP/M has data areas mixed in with its code. The replacement
    > for CP/M 2.2 (dospls25 and dosplsor, both .zip) is better
    > organized, but still has some slight problems to do with errors as
    > I recall (I wrote it 20 years ago). You can get those zip files
    > at:
    >
    >


    However, on reading this thread later, it is obviously a pointless
    operation. The delays in booting CP/M do not involve reading the
    code in. They are the result of opening a drive for writing, which
    involves reading its directory and forming a list of available
    blocks on that drive. For large drives this can take perceptible
    time.

    This is where MSDOS and FAT file systems have an advantage. They
    keep a permanent structure on the disk specifying the free blocks.
    However, if that storage is damaged the whole disk may be destroyed
    before you know anything is wrong.

    --
    [mail]: Chuck F (cbfalconer at maineline dot net)
    [page]:
    Try the download section.


    ** Posted from http://www.teranews.com **

  14. Re: Minimalist CP/M system?

    On Jun 15, 10:44*pm, Gregg C Levine wrote:
    > Hello!
    > As is usual for this time period I have a new project taking shape.
    > (Or it should be...)
    >
    > What would be considered a simple CP/M-80 system? Memory, and
    > associated peripherals, plus disk drive as one of the peripherals.
    > ---
    > Gregg drw...@att.net


    Hi Gregg,
    Do RAM/ROM block devices qualify as a disk drive?

    Thanks!

    Andrew Lynch

  15. Re: Minimalist CP/M system?

    On Fri, 20 Jun 2008 06:49:07 -0800, glen herrmannsfeldt
    wrote:

    >no.spam@no.uce.bellatlantic.net wrote:
    >
    >(snip, I wrote)
    >>>How hard is it to run CP/M completely from ROM?

    >
    >> CP/M2 has data areas in the code segment. They are easy
    >> to isolate in the source if you willing to reassemble.

    >
    >> However...
    >> Then you need to figure where to put the data areas and under the
    >> rom in high ram is subject to invasion by things that load high in ram
    >> like DDT. You also have to put the buffers in the bios somethere
    >> too.

    >
    >> Using 32k rams, 32k roms it's easy to invert A15 at startup to put
    >> rom at 0000 copy to ram then flip the bit (Uses 1 xor gate).

    >
    >It would be nice in ROM where you don't have to worry
    >about writing over it. Otherwise, instead of just one
    >gate arrange so that initially the ROM is read and RAM is
    >written, copy the whole ROM over, then switch to RAM only.
    >
    >That will take more than one XOR gate (and a latch for
    >its input) but maybe not much more.
    >


    If you only have 32k of ram then thats it. What controles the input
    to that gate is a different story.

    Allison


    >-- glen



  16. Re: Minimalist CP/M system?

    On Fri, 20 Jun 2008 06:49:07 -0800, glen herrmannsfeldt
    wrote:

    >It would be nice in ROM where you don't have to worry
    >about writing over it. Otherwise, instead of just one
    >gate arrange so that initially the ROM is read and RAM is
    >written, copy the whole ROM over, then switch to RAM only.


    The only thing worse than re-inventing a wheel is re-inventing
    an OLD wheel.

    Let's assume you're going to use a Z-80.

    Then what you want to do is called BANK SWITCH.
    Z-80s could do that. In ONE instruction.

    The BigBoard II had six sockets for ROM that you could
    access just like that. You could even program them right
    there in those sockets (well, the EProm kind anyway)

    Ferguson put the hardware BIOS in a second bank
    Seems to me, some people did CP/M-3 like that.

    Bill

  17. Re: Minimalist CP/M system?

    On Fri, 20 Jun 2008 14:48:11 -0700 (PDT), lynchaj
    wrote:

    >On Jun 15, 10:44*pm, Gregg C Levine wrote:
    >> Hello!
    >> As is usual for this time period I have a new project taking shape.
    >> (Or it should be...)
    >>
    >> What would be considered a simple CP/M-80 system? Memory, and
    >> associated peripherals, plus disk drive as one of the peripherals.
    >> ---
    >> Gregg drw...@att.net

    >
    >Hi Gregg,
    >Do RAM/ROM block devices qualify as a disk drive?
    >
    >Thanks!
    >
    >Andrew Lynch


    Hello!
    Given how this thread is evolving, actually yes I do consider them.
    But only on a wet Saturday Morning in June.

    Why? Do you have such a system running? And can point me towards a
    good photo series?
    --
    Gregg drwho8@worldnet.att.net

  18. Re: Minimalist CP/M system?

    On Jun 21, 12:34*am, Gregg C Levine wrote:
    > On Fri, 20 Jun 2008 14:48:11 -0700 (PDT), lynchaj
    > wrote:
    >
    >
    >
    >
    >
    > >On Jun 15, 10:44*pm, Gregg C Levine wrote:
    > >> Hello!
    > >> As is usual for this time period I have a new project taking shape.
    > >> (Or it should be...)

    >
    > >> What would be considered a simple CP/M-80 system? Memory, and
    > >> associated peripherals, plus disk drive as one of the peripherals.
    > >> ---
    > >> Gregg drw...@att.net

    >
    > >Hi Gregg,
    > >Do RAM/ROM block devices qualify as a disk drive?

    >
    > >Thanks!

    >
    > >Andrew Lynch

    >
    > Hello!
    > Given how this thread is evolving, actually yes I do consider them.
    > But only on a wet Saturday Morning in June.
    >
    > Why? Do you have such a system running? And can point me towards a
    > good photo series?
    > --
    > Gregg drw...@worldnet.att.net- Hide quoted text -
    >
    > - Show quoted text -


    Hi Gregg,
    Yes, the N8VEM SBC does use RAM/ROM CP/M block devices and it works.
    The PCB is available now for home brew builders but that is another
    thread. You can check out the project and its photos at:
    http://groups.google.com/group/n8vem

    One of the builders finished his SBC and published a photo spread on
    Flickr available here: http://www.flickr.com/photos/twylo/s...7605637029141/

    The N8VEM SBC design sort of evolved based on some of my ideas, some
    of Allison's, and some discussion on ALPACA, etc. Basically, the core
    SBC gives you fully CP/M if you want it. The SBC boots into a RAM
    monitor where it acts like you'd expect a minimal Z80 system would.
    If you want, it can boot CP/M with the "c" command.

    CP/M starts up and uses the A: drive (32K ROM) and the F: drive (992K
    ROM) for its system tracks and CP/M transient commands. CP/M can
    write temporary files to the B: drive (448K RAM). Files can be
    transferred in and out of the SBC using XMODEM "on the fly" or you can
    burn your own programs, data, or whatever into the EPROM for ROM drive
    usage. The ROM drives have some programs installed already like BBC
    basic, a full screen editor, CP/M transient commands, the RTC
    application, etc.

    The plan is to provide a low cost, reliable, flexible core SBC with CP/
    M as its OS. It gives some simple IO peripherals like 16550 UART
    serial, 8255 PPI parallel, DS1302 RTC clock, and various output
    discretes from the latches, etc. It has plenty of RAM and ROM for
    expansion.

    If you want, you can then expand the system by plugging the SBC into
    an ECB backplane. From there it can access "real" external
    peripherals. Of course, its been all I can do just to make the SBC as
    making a manufactured PCB has been more difficult than I imagined.
    Eventually, the goal is to start making some ECB peripherals.

    However, the next step is to make the ECB backplane and then the ECB
    bus debugger. Those peripherals sort of go together and I have
    prototype versions on my bench. They work fine but are made using
    prototype boards and point to point wiring. Obviously they are not
    ready for public release or even close.

    This is probably more than you wanted to know. I hope this helps.

    Thanks and have a nice day!

    Andrew Lynch

  19. Re: Minimalist CP/M system?

    On Fri, 20 Jun 2008 22:07:18 -0500, Bill
    wrote:

    >On Fri, 20 Jun 2008 06:49:07 -0800, glen herrmannsfeldt
    > wrote:
    >
    >>It would be nice in ROM where you don't have to worry
    >>about writing over it. Otherwise, instead of just one
    >>gate arrange so that initially the ROM is read and RAM is
    >>written, copy the whole ROM over, then switch to RAM only.

    >
    >The only thing worse than re-inventing a wheel is re-inventing
    >an OLD wheel.
    >
    >Let's assume you're going to use a Z-80.
    >
    >Then what you want to do is called BANK SWITCH.
    >Z-80s could do that. In ONE instruction.


    Uhm I think your confusing register banks with the 16bit
    addresable space.

    Z180 or better Z280, now theres a different cat.


    >The BigBoard II had six sockets for ROM that you could
    >access just like that. You could even program them right
    >there in those sockets (well, the EProm kind anyway)
    >
    >Ferguson put the hardware BIOS in a second bank
    >Seems to me, some people did CP/M-3 like that.


    Ah yep, I do too. Requires one addresable port to add
    the needed control/address bits.

    Allison
    >
    >Bill



  20. Re: Minimalist CP/M system?

    On Jun 21, 1:42 pm, no.s...@no.uce.bellatlantic.net wrote:

    > Ah yep, I do too. Requires one addresable port to add
    > the needed control/address bits.


    If you have SPI already (eg, the mass storage is SD) than it could n
    be done with an additional select line for selecting a serial shift
    register for writing?

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