Home built Z80 computers - CP/M

This is a discussion on Home built Z80 computers - CP/M ; A bit slow here right now so thought I would post a link http://www.hanssummers.com/ About a quarter of the way down the page is his Z80 computer projects...

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  1. Home built Z80 computers

    A bit slow here right now so thought I would post a link
    http://www.hanssummers.com/
    About a quarter of the way down the page is his Z80 computer projects

  2. Re: Home built Z80 computers

    In article ,
    Bob Yates wrote:

    > A bit slow here right now so thought I would post a link
    > http://www.hanssummers.com/
    > About a quarter of the way down the page is his Z80 computer projects


    Perhaps a group sponsored Z80 project might be fun? I know there is the
    P112, but I'm thinking of something 'traditional'.

  3. Re: Home built Z80 computers

    In article ,
    ziggy writes:
    > In article ,
    > Bob Yates wrote:
    >
    >> A bit slow here right now so thought I would post a link
    >> http://www.hanssummers.com/
    >> About a quarter of the way down the page is his Z80 computer projects

    >
    > Perhaps a group sponsored Z80 project might be fun? I know there is the
    > P112, but I'm thinking of something 'traditional'.


    I still have an un-populated Xerox-820 board up in my attic somewhere.
    Maybe I should just put it up on Ebay? Wouldn't that be about as
    traditional as you can get?

    bill

    --
    Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
    bill@cs.scranton.edu | and a sheep voting on what's for dinner.
    University of Scranton |
    Scranton, Pennsylvania | #include

  4. Re: Home built Z80 computers

    > I still have an un-populated Xerox-820 board up in my attic somewhere.

    Do you remember where you bought it?
    I too bought an unpopulated bigboard but it came with the ROMS
    and very complete information including schematic.

    I just gave away my 3 complete running Xerox bigboards
    because I just can't get around to using them,
    particularly since I'm focusing on single board systems
    such as PIC and eZ80.
    --

    -- mejeep deMeep ferret!

  5. Re: Home built Z80 computers

    In article ,
    jeffj@panix.com (Jeff Jonas) writes:
    >> I still have an un-populated Xerox-820 board up in my attic somewhere.

    >
    > Do you remember where you bought it?


    Hamfest in Middletown, NY. I was really into Packet Radio in
    those days and planned to set up a BBS. But I ended out
    concentrating on the transport side of things.

    > I too bought an unpopulated bigboard but it came with the ROMS
    > and very complete information including schematic.
    >
    > I just gave away my 3 complete running Xerox bigboards
    > because I just can't get around to using them,
    > particularly since I'm focusing on single board systems
    > such as PIC and eZ80.


    Obviously, for various reasons, Inever got around to it either. :-)

    bill

    --
    Bill Gunshannon | de-moc-ra-cy (di mok' ra see) n. Three wolves
    bill@cs.scranton.edu | and a sheep voting on what's for dinner.
    University of Scranton |
    Scranton, Pennsylvania | #include

  6. Re: Home built Z80 computers

    ziggy wrote:
    > Perhaps a group sponsored Z80 project might be fun? I know there is the
    > P112, but I'm thinking of something 'traditional'.


    I'd be happy to share the desing for my Databug. It's a 6.5" x 2.5" PC
    board with a Z80, two bytewide memory sockets for up to 1meg of memory,
    bank switching logic, two serial ports (on RS-232, one special), a
    3-channel A/D converter, and switchmode power supply. It was designed
    for a data logger, but could run CP/M using the memory above 64k as its
    disk. Not exactly traditional, but very cheap (all the parts cost under
    $20).

    Another thought I've had is to make boards to reproduce the Heathkit H8
    computer. It's a very simple, generic design, easy to build and modify;
    and it easily runs CP/M.
    --
    Ring the bells that still can ring
    Forget the perfect offering
    There is a crack in everything
    That's how the light gets in -- Leonard Cohen
    --
    Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net

  7. Re: Home built Z80 computers

    Sounds like a very nice design. If you could really share the project
    (at least) i'm interested.
    BTW it's never a good thing to loose this kind of projects / schematics.


  8. Re: Home built Z80 computers

    I will gladly participate in any way I can.
    Hans' site isn't the only good one; there's about a
    half-dozen or so that I rate from 'good' to 'excellent',
    Hans' being the gold standard- his inclusion of
    schematics, and the walk-through of the logic behind
    his VD circuits are simply a joy to read. I'm too darn
    tired to think of the other sites, but Google Dincer Aydin
    and coprolite software, to get ya started. I remember
    before signing up for this site tracking down many a page
    form google searches like "z80 home homebrew built made"
    and others. A case of virtual R/C cola goes to the person who
    can two pix of robots built with the z80! If only ever found two,
    at least that were billed as such.

    I'll be lurking to see what becomes of this thread.

    Nighty-nite,
    Tarkin


  9. Re: Home built Z80 computers

    Tarkin wrote:
    >
    > [snip...] [snip...] [snip...]
    >
    > I'll be lurking to see what becomes of this thread.
    >

    How about taking a look at _Build Your Own Z80 Computer_, by
    Steve Ciarcia, Byte Books, McGraw-Hill, 1981. I know that the
    power supply part can be disregarded...one can always use a
    "canned" PC supply. I am *not* sure about the availability of
    the other parts used in the design in this book.

    --
    +----------------------------------------------------------------+
    | Charles and Francis Richmond richmond at plano dot net |
    +----------------------------------------------------------------+

  10. Re: Home built Z80 computers


    Charles Richmond wrote:
    > Tarkin wrote:
    > >
    > > [snip...] [snip...] [snip...]
    > >
    > > I'll be lurking to see what becomes of this thread.
    > >

    > How about taking a look at _Build Your Own Z80 Computer_, by
    > Steve Ciarcia, Byte Books, McGraw-Hill, 1981. I know that the
    > power supply part can be disregarded...one can always use a
    > "canned" PC supply. I am *not* sure about the availability of
    > the other parts used in the design in this book.
    >
    > --
    > +----------------------------------------------------------------+
    > | Charles and Francis Richmond richmond at plano dot net |
    > +----------------------------------------------------------------+


    This is just a bunch of random ramblings on my part but I was thinking
    of system loosly based on the Xerox 820-1. All of the schematics for
    this system are available and so is the source code for the ROMS. I
    would drop the video circuits and use one of the serial ports for
    communication with a terminal emulator. All those DRAMS could be
    replaced with a single byte wide SRAM chip. I also have the Plus-2 ROMS
    but don't have the source. I also have the circuit for the double
    density controller adaptor which the Pluse-2 ROM supports. All of the
    Z80 family chips are still available. Anyway, just thinking outloud.

    Don


  11. Re: Home built Z80 computers

    Actually, I'm going to take this opportunity
    to restate a question I had Gaby put up on the
    Z80 site she manages (under 'software sites'):
    Does anyone have a good, well-rounded tute
    on serial-port programming for the Z80 family
    SIO/SCC chips? I have 1 or 2 of the Z085300
    SCC's, however, I am under under the impression
    that the chip is signal/code compatable with the
    early SIO's...much like the Z80 is compatable
    w/ the 8080. The SCC is very feature-laden...
    to the point that the documentation becomes a
    slow read for someone as impatient as myself.

    I am familiar w/ the basics of serial communications;
    I just don't want to have to re-invent the wheel.
    Some nice example code which demonstrates
    initializing the registers, interrupt vs. non-interrupt
    implementations, and external circuitry do's and
    don'ts are what I am looking for.

    >I also have the Plus-2 ROMS but don't have the source


    If you have an older-ish pc, dos or win98, the free
    Hitec C compiler, some skills, some components,
    and the the inclination, you can hack together a
    parallel-port ROM reader. I made a four-chip
    EEPROM programmer with the above list.
    The command sequences for writing and block
    erase, and the latch firmware were the hardest
    parts to code (oh, and the UI, but that's 'cos I
    am a horrible C programmer). The project was
    a blast, and I learned *a lot* about firmware
    and such. For free, and it's age, the Hitec C
    compiler is purty darn nice, IMO.

    Well, now I am just rambling.

    Cheers,
    Tarkin


  12. Re: Home built Z80 computers

    >Does anyone have a good, well-rounded tute
    >on serial-port programming for the Z80 family
    >SIO/SCC chips?


    *oy* I cannot find the source to the
    SDLC driver I wrote years ago.

    I remember
    - preferring the AMD databook to the Zilog
    for the chip descriptions and register programming
    - initializing the registers is NOT just from 0-15
    but in a specific sequence, depending on the chip's mode.
    Therefore the initialization code is specific to each port's mode:
    sync or async, clock source, full SDLC or partial, etc.
    - I used interrupt mode and the most important thing to remember is
    keeping the driver's state machine in sync with the chip's internal state
    for each port. Not every state change causes an interrupt
    (ex: writing a character to the XMT buffer clears the xmt status bit),
    so my driver kept a copy of the PREVIOUS state
    and XOR-ed that with the current state register
    to ascertain what change caused the interrupt.
    --

    -- mejeep deMeep ferret!

  13. Re: Home built Z80 computers

    In article <1144432641.524416.113450@g10g2000cwb.googlegroups. com>,
    "Don" wrote:

    > Charles Richmond wrote:
    > > Tarkin wrote:
    > > >
    > > > [snip...] [snip...] [snip...]
    > > >
    > > > I'll be lurking to see what becomes of this thread.
    > > >

    > > How about taking a look at _Build Your Own Z80 Computer_, by
    > > Steve Ciarcia, Byte Books, McGraw-Hill, 1981. I know that the
    > > power supply part can be disregarded...one can always use a
    > > "canned" PC supply. I am *not* sure about the availability of
    > > the other parts used in the design in this book.
    > >
    > > --
    > > +----------------------------------------------------------------+
    > > | Charles and Francis Richmond richmond at plano dot net |
    > > +----------------------------------------------------------------+

    >
    > This is just a bunch of random ramblings on my part but I was thinking
    > of system loosly based on the Xerox 820-1. All of the schematics for
    > this system are available and so is the source code for the ROMS. I
    > would drop the video circuits and use one of the serial ports for
    > communication with a terminal emulator. All those DRAMS could be
    > replaced with a single byte wide SRAM chip. I also have the Plus-2 ROMS
    > but don't have the source. I also have the circuit for the double
    > density controller adaptor which the Pluse-2 ROM supports. All of the
    > Z80 family chips are still available. Anyway, just thinking outloud.
    >
    > Don


    Oddly enough i just ran across that book in my garage this last weekend.

    From what it looks like from first glance, its still doable, and could
    reduce the parts count greatly by using a small/cheap pla/cpld/fpga.
    Though that might make it less 'real' in the process.

  14. Re: Home built Z80 computers

    Thanks for the tip. I realized the bit about the
    registers initializtion being specific to operating
    parameters and port mode, but it's gotchas
    like keeping a copy of the xmt status that I
    suspected would cause hours of r&d and
    forensic debugging.

    I am off to hunt down the AMD spec/docs.

    To birng us back on track, what's the consensus
    on a z80-based homebrew? Book? Databug?
    Shameless eastern-bloc rip-off of the p112?
    Xerox-clone[1] (snicker)?

    Thanx,
    Tarkin
    [1] I am old enough to remeber when mimeographs
    were replaced, the new process was called
    "Xeroxing".


  15. Re: Home built Z80 computers


    Tarkin wrote:
    > Thanks for the tip. I realized the bit about the
    > registers initializtion being specific to operating
    > parameters and port mode, but it's gotchas
    > like keeping a copy of the xmt status that I
    > suspected would cause hours of r&d and
    > forensic debugging.
    >
    > I am off to hunt down the AMD spec/docs.
    >
    > To birng us back on track, what's the consensus
    > on a z80-based homebrew? Book? Databug?
    > Shameless eastern-bloc rip-off of the p112?
    > Xerox-clone[1] (snicker)?
    >
    > Thanx,
    > Tarkin
    > [1] I am old enough to remeber when mimeographs
    > were replaced, the new process was called
    > "Xeroxing".


    I remember "using" mimeograph machines. Xerox didn't exist at that
    time. :-)

    My reason for suggesting the 820-1, or bigboard for that matter, is
    that it is a fairly stable starting point. I have know idea of the
    skills of the readers of this list so thought a known starting point
    would be good. I had an 820-1 many years ago. It reminded me of two
    aircraft carriers parked side by side. :-) That puppy was big!

    Anyway, the design could be simplified and then expanded on. My 820 was
    hacked to the max. I had doubled the speed from 2.5 to 5 MHz, added the
    double density adaptor, hard drive interface, 68000 co-processor and
    changed the video timing to use a hercules monitor. It looked more like
    a high rise apartment complex than a computer board. :-)

    Don


  16. Re: Home built Z80 computers


    I have a complete, functional 820-1 w/ 8" floppy drives, diskettes, and
    manuals that I reconditioned. Thinking of selling soon.

    But what would be the point in another homebrew z80 w/ serial port?
    Much easier to assemble an S-100 w/ Z80 cpu.. something else I have
    done recently. IMSAI chassis, Cromemco ZPU, CompuPro Ram17
    64k+Disk1+Interfacer1. CP/M 2.2 so far, is booting and running from
    ROM. I plan on making a graphics + voice syn board too.

    One cool idea might be to make a Z80 SBC with the above features,
    including the graphics (TMS9928) and voice (SPL0256). THen see if we
    can make any graphics games that will run under CPM, and share them.

    ~ J


  17. Re: Home built Z80 computers

    Tarkin wrote:
    > Thanks for the tip. I realized the bit about the
    > registers initializtion being specific to operating
    > parameters and port mode, but it's gotchas
    > like keeping a copy of the xmt status that I
    > suspected would cause hours of r&d and
    > forensic debugging.


    > I am off to hunt down the AMD spec/docs.


    > To birng us back on track, what's the consensus
    > on a z80-based homebrew? Book? Databug?
    > Shameless eastern-bloc rip-off of the p112?
    > Xerox-clone[1] (snicker)?


    If you want to do something like the P112, that is, be entirely
    compatible with it, you'll have to do some rather delicate surface-mount
    soldering. Those two surface-mount chips aren't available in
    through-hole packages.

    If it's a Bigboard clone, then you'll probably have loads of "fun"
    tracking down currently-available parts and an increasingly rare naked
    CRT. Old serial terminals are easily and cheaply available.

    --
    David Griffith
    dgriffi@cs.csbuak.edu <-- Switch the 'b' and 'u'

  18. Re: Home built Z80 computers


    "Tarkin" wrote in message
    news:1144892003.229953.317150@t31g2000cwb.googlegr oups.com...

    > Shameless eastern-bloc rip-off of the p112?


    Why do a rip-off? The P112 is available now; it works well, runs
    fast, and carries the 'standard' CP/M I/O compliment, ie, 2 x Serial,
    Parallel, and 1.44MB Floppy ports. It runs at 16MHz, has been tested
    at 18.432MHz, can carry up to 1MB RAM, and has some expansion
    capability. It comes with ZSDOS and a fully-implemented Z-System.

    [Shameless plug] And there is a P112-specific GIDE adapter kit (IDE
    HD interface) available, too - also available now. It comes with Hal
    Bower's B/P BIOS, tailored to the P112, and adds a banked ZSDOS,
    RamDisk, and multiple IDE partitions with up to 512MB of HDD storage.
    Included is the ability to use the P112-GIDE to read CDROM disks and
    copy files to the P112 HD.

    So again, why do a rip-off?


    Terry Gulczynski

    P112 info here:
    http://www.cs.csubak.edu/~dgriffi/proj/p112/
    P112-GIDE info here: http://home.cfl.rr.com/tgcons/



  19. Re: Home built Z80 computers

    >Perhaps a group sponsored Z80 project might be fun? I know there is the
    >P112, but I'm thinking of something 'traditional'.


    This was suggested by ziggy.

    >I'd be happy to share the desing for my Databug
    >Another thought I've had is to make boards to reproduce the Heathkit H8
    >computer. It's a very simple, generic design, easy to build and modify;
    >and it easily runs CP/M.


    Sayeth Lee H.

    And den:
    >Sounds like a very nice design. If you could really share the project
    >(at least) i'm interested. (pbetti)


    >How about taking a look at _Build Your Own Z80 Computer_, by
    >Steve Ciarcia, Byte Books, McGraw-Hill, 1981. (Charles R)


    >This is just a bunch of random ramblings on my part but I was thinking
    >of system loosly based on the Xerox 820-1.


    Up to this point, I thought simplicity and 80's-ish parts were the
    order of the day.

    >reduce the parts count greatly by using a small/cheap pla/cpld/fpga.
    >Though that might make it less 'real' in the process. (ziggy)


    Which kinda (IMO) wandered away from the 'point'; thus the bit about
    'less real' (I think! I don't presume to speak for ziggy!)

    My quip about the P112 was meant as kind of a joke...I am very
    aware of the availability of kits, and the plans + schem's + source
    (kudos, BTW; an excellent endeavor, all the way 'round!). I also felt
    that the P112 was kinda too high-tech for what I felt was the 'point'.
    The Eastern-Bloc bit was a reference to all the field-expedient cloning

    of computers that went on days gone by. Spectrum clones, for example.
    There are some Bilingual Polish,Czech, and Russian enthusiasts out
    there
    who are doing laudable work on documenting these fascinating machines,
    and the joke was not meant to offend in any way, either to our
    bit-brothers
    in the East, or any of the fine developers of the P112.

    Besides, after reading about some of the struggles you (the P112 folks)
    had
    during serial comm's debugging, I thought that that experience would be
    much
    less harrowing and far more enjoyable if working on a hombrew project,
    and
    not under a shipping or release constraint.

    As far as the grafix vs. tty debate, I thought that there might be a
    middle ground
    between two extremes I've read about:
    1) The PIC vcr-pong game. If you haven't heard about this, check it out
    here:
    http://dt.prohosting.com/pic/pong.html
    Anywho, this has got to be graphics output at it's most basic. I was
    wondering
    if it wouldn't be feasible to adapt the concept to an output for a
    homebrew
    Z80-based comp, with text at first and graphics later.
    2)Hans' work. I consider Hans' work the other end of the Spectrum
    (snicker).
    While brilliant, it seems complex. Of course, on challenging days, a
    baked potato
    seems complex to me...

    But I am also entirely for doing the user I/O as a tty: I have a
    Toshiba T1200 and
    an Apple p.b. 145, as well as various win and linux boxes that beg to
    be put
    to use as terminals.

    Dambit, I am rambling again. I blame the potatos.

    TTFN,
    Tarkin


  20. Re: Home built Z80 computers

    In article ,
    dgriffi@cs.csbuak.edu (Dave Griffith) wrote:

    > Tarkin wrote:
    > > Thanks for the tip. I realized the bit about the
    > > registers initializtion being specific to operating
    > > parameters and port mode, but it's gotchas
    > > like keeping a copy of the xmt status that I
    > > suspected would cause hours of r&d and
    > > forensic debugging.

    >
    > > I am off to hunt down the AMD spec/docs.

    >
    > > To birng us back on track, what's the consensus
    > > on a z80-based homebrew? Book? Databug?
    > > Shameless eastern-bloc rip-off of the p112?
    > > Xerox-clone[1] (snicker)?

    >
    > If you want to do something like the P112, that is, be entirely
    > compatible with it, you'll have to do some rather delicate surface-mount
    > soldering. Those two surface-mount chips aren't available in
    > through-hole packages.
    >
    > If it's a Bigboard clone, then you'll probably have loads of "fun"
    > tracking down currently-available parts and an increasingly rare naked
    > CRT. Old serial terminals are easily and cheaply available.


    Personally i dont think 'cloning' anything is the right idea, it should
    be something unique, designed from scratch.

    I also agree that we will have to make some concessions for the loss of
    'classic' components over the years, but i would think we should get by
    with a bare minimum of 'modern' parts in this thing.

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