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Thread: Trying Hi Tech C with different results...

  1. #21

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    Quote Originally Posted by alank2 View Post
    I'd like to know too.

    Also, is the command echo a feature that is compiled in, or is it configurable. If configurable, what command would enable/disable it?
    The CP/M BDOS is defined as the top of the TPA. All memory above that is reserved for the system. CP/M defines that a JMP at location 0005 will go to the BDOS entry for function calls. CP/M has established that the BDOS entry must be the first (reserved) part of the BDOS. So, examining the JMP address at location 0005 will tell you the start of the BDOS - and thus, the top of the TPA.

    In practice, the first 6 bytes of the BDOS are reserved for the serial number, but that is not used after booting and normally is totally ignored. So, if you look at the JMP at location 0005 you'll see an address of the form xx06. The "xx" defines the top boundary of the TPA. Programs that use large amounts of memory must look at this JMP address and ensure that they do not overrun the BDOS.

    As previously mentioned, there are cases where somethign attaches itself beneath the BDOS, in CP/M 3 these are RSX (Resident System eXtensions). Another example is DDT/SID. These programs modify the JMP at location 0005 and thus affect the TPA - although in a more-temporary manner.

    The CP/M 3 command echo is an option that I think can be set by GENCPM, but is also controlled by a utility. I'd have to go look at documents or HELP to tell which. Check your boot disk for a PROFILE.SUB file, it may be getting set in that.

  2. #22

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    That was it - there was a profile.sub that has this line:
    SETDEF * A: [ORDER=(COM,SUB) DISPLAY UK]

    I renamed it and that stopped it.

  3. #23
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    Quote Originally Posted by alank2 View Post
    Hi Chuck,

    Here is the file - http://www.classiccmp.org/cpmarchive...ip/cpmplus.zip

    Thanks!
    I'm not interested in your copy of CP/M 3--I've already got a system that's running it natively. I'd like to see the program that's giving you trouble on CP/M 3 and try it on my system. No .IMDs, please, just the files.

  4. #24

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    Hi Chuck,

    I just took your tpa.asm and used asm and load on it to turn it into a COM file, nothing more than that. The way it was echoing back the command was figured out so no worries.

    Thanks!

    Alan

  5. #25
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    Before I drift away from this thread, I thought about the bit of converting a one-byte binary number to decimal and this was the best I could come up with:

    Code:
    ;
    ;      Assume binary number between 0-99 is in register H
    ;      Output will be 2 ASCII digits in HL, with the high order digit in L.
    ;
            MVI     L,0
            LXI     B,0F601h
    L1:     DAD     B
            JC      L1
            LXI     B,3A2Fh
            DAD     B

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