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  1. Replies
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    Thanks i will look for it . Cheers! Hey I...

    Thanks i will look for it . Cheers!

    Hey I tried.. no luck. Do you have a link? Thanks again
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    disk test utility for CP/M 80?

    Hi everyone,
    Wondering if there is a CP/M program that tests disks?
    Ideally, something that is configurable for # of tracks, # of sectors, and sector size.
    Any suggestions?
    thanks!
  3. My projects.. 1. Getting REXCPM hardware...

    My projects..

    1. Getting REXCPM hardware done and launched. First hardware shipped and so far so good. REXCPM is a memory card for Model 100 that enables CP/M.

    2. Created and tested a dual...
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    Zenith ZFA 161

    Interesting old Zenith luggable.
    ...
  5. Geez, I just made a board version myself to do...

    Geez, I just made a board version myself to do exactly that - include an RS232 connector.
    The original Geoff design claimed to work for TTL and RS-232; did you find that the RS-232 support was...
  6. great thread topic! I have a very hard time with...

    great thread topic!
    I have a very hard time with programming the PIC using the MPLAB tool and a PICKIT3. It never boots up. I can't figure out how to go straight from Compiled C code to the PIC....
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    Can you elaborate on your last comment? What is...

    Can you elaborate on your last comment? What is strange, and what is cross shopping? Thanks.
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    UTSOURCE has stock, they sell via Ebay also. I...

    UTSOURCE has stock, they sell via Ebay also. I think they claim some of their parts are "new" while others are used/reclaimed parts.

    Octopart seems to suggest there is stock out there.
    ...
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    CP/M-80 on TRS80 Model 100

    Quick note to mention two things.

    First, a new RAM upgrade for M100 is available called REXCPM, and it enables CP/M-80 to operate on M100 with an internal 3.5 MB ramdisk. See
    ...
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    Tandy 1000 RL HD in mint condition

    Looks nice.

    https://www.kijiji.ca/v-desktop-computers/ottawa/tandy-1000-rl-hard-drive-vintage-computer/1505991907
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    Doug, It is a little tricky to explain, but I...

    Doug,
    It is a little tricky to explain, but I will try.

    Regardless of CPU selection, there are valid ISR hooks available in lower memory.
    As part of the interrupt processing, for the case where...
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    regarding tristate in Reset: The Zenith Z100 has...

    regarding tristate in Reset:
    The Zenith Z100 has full schematics on line and that's where I got the idea to use a RESET methodology. This approach is more intended for a "switchable" mode where...
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    ding ding, .. I think I do need to transfer the...

    ding ding, .. I think I do need to transfer the state of the interrupt mask back and forth. Thanks for the poke.
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    Hard to have this level of detailed technical...

    Hard to have this level of detailed technical discussion via message board. Appreciate your comments, and it is cause to double check our thinking for sure.
    There are a few things working in our...
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    Yah.. the original machine has 80c85 plus a lot...

    Yah.. the original machine has 80c85 plus a lot of useful routines and interrupt handling in ROM. When we overlay CP/M on it we can run in 8085 and all is well. BUT lots of CPM applications are...
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    So that's not so bad. Different interrupt...

    So that's not so bad. Different interrupt vectors, different way to handle interrupt mask. Inverted interrupts. Wait state.
    All sorted.
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    Yes that's true. Thought that was z80 too. ...

    Yes that's true. Thought that was z80 too. Guess I better read a datasheet or two
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    Hi Chuck, What does NSC800 do that Z80 does not? ...

    Hi Chuck, What does NSC800 do that Z80 does not? Instruction set is the same I think. It has the bus config of the 8085 which is why it can shoehorn into the M100.

    I was thinking it is the same...
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    Here's the article on a dual CPU card for S100- ...

    Here's the article on a dual CPU card for S100- (not Z100... that was already dual CPU)

    61274
    61275
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    I have a copy of that article actually, and that...

    I have a copy of that article actually, and that is what I built more or less.
    I ahve the dual CPU working. don't even need the wait states.
    The article I read was for Z100.
    I may be able to do...
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    great points! Right now, my hardware...

    great points! Right now, my hardware implementation did not anticipate such a use case.
    I'll think about your suggestion. I have a section of code now that does the full state store - lots of pops...
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    The original computer is the TRS-80 model 100....

    The original computer is the TRS-80 model 100.
    We have CP/M running now, using 8085.
    the NSC800 will support Z80 applications in CP/M, but CP/M relies on the M100 ROM for a bunch of support.

    The...
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    processor switching mid-code

    Contemplating a dual CPU implementation containing 80C85 and NSC800 (Z80).

    Have read a few threads recently and seen
    http://www.righto.com/2013/08/reverse-engineering-8085s-decimal.html
    and...
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    OK, I will give it a try. I'm bogged down with...

    OK, I will give it a try. I'm bogged down with getting a Z80 to run in my M100, and I'm almost there.
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    I did use CLS:RUN... Pi calculation times for...

    I did use CLS:RUN...

    Pi calculation times for TRS-80 Model 100:
    100: 3.25391
    300: 27.09375
    1000: 291.57813
    3000: 2563.17188

    Running in BASIC, 32k RAM, 80C85@ 2.4576MHz
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