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Re: Getting CPM 2.2 running on a set of N8VEM S-100 cards


I have taken the same approach as you have done though I don't have
the floppy card but have the IDE card instead.
I am at the same place you are the moment.  My plan is to use the simh
simulator to create my image into a file mounted
on the simulator and write that file as a raw image onto the CF card.
That way I can do all the coding on PC (in my case a
Mac) and then bring the CF card over to the IDE board that has a CF to
IDE adapter on it.


On Feb 17, 11:31 am, nbreeden <nbre...@comcast.net> wrote:
> Having assembled my alpha S-100 VDU I sat down to start testing it and
> realized I was missing a critical part; the ability to boot CPM on my
> system based on N8 S-100 cards.
> My system Config:
>   Z-80 Master CPU - tested and known good
>   4 megabyte Static RAM card - 1MB installed - tested and known good
>   ZFDC - tested and known good
>   Serial I/O - tested and known good
>   EPROM - not tested
> You may ask how I tested these without being able to boot the system,
> this is what I have done:
> To test the SERIAL I/O card I wrote code that I burned into EPROM for
> the CPU card; this card tested the Serial I/O card.
> I've taken the ZAPPLE monitor along with code from a Z-80 monitor John
> wrote (www.s100Computers.com) and created my own version of it. One of
> the functions it has is the ability load HEX files produced by TASM. I
> ported John's code for the ZFDC from CPM programs to standalone
> programs under TASM. I then assemble them and via the text file send
> function in Teraterm I loaded these into RAM for execution. I have
> been able to adjust the ZFDC and have been able to format 3.5"
> floppies.
> Next using the monitor I wrote a set of playback files (again for
> TeraTerm) that using the PORT I/O function of my monitor along with
> the LOAD/DUMP memory functions was able to test all 16K blocks of the
> 1MB memory space to verify the basic functionality (I know the block
> selects work, I know the RAM can be written and read back).
> The Monitor has John's code to read the boot sector from a floppy and
> start it to bring up CPM.
> So, now I need a floppy with CPM to boot.
> Having completed a ZETA and having it running well with 2 3.5"
> floppies this seems like a good platform to write the system to
> floppy; it already has the tools to get the image to the RAM Disk (XM)
> and the program to write the system to floppy (WRITESYS.COM).
> Next I checked out the BUILD directories from Doug's SVN site and
> began digging through them to understand how it works; this is what I
> have concluded in looking at it:
> Porting the CBIOS for the S-100 config listed above should be straight
> forward, John already provided the code to get the basics working.
> Building a CPM image (the SYS file) and the standalone file (the COM
> file) using looks pretty straight forward.
> Questions:
> 1) It's unclear to me if the ROM image can be used; the N8 does some
> tricks to map SRAM or EPROM into the Z80 address space; using the
> extended address space of the Z80 CPU card this would be possible
> however only the 2 lower 16K blocks can be swapped. Can this be done?
> Should it be done?
> 2) Should I add the functionality to build a CPM image for the S-100
> system to the current build tree or do we want to start a new tree?
> 3) Ultimately I hope to have a CPM floppy image downloadable so
> someone can build the basic board set; image a floppy and boot the
> system using the default jumper settings. Is there value in doing
> this?
> -Neil