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107 lines
3.2 KiB
Plaintext
107 lines
3.2 KiB
Plaintext
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% Time-stamp: <06/06/94 23:08:26 Michael Bischoff moulder>
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% CP/M emulator README
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Introduction:
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=============
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Type 'UNIX' at the CCP prompt to leave the emulator.
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(Or ctrl-@, followed by 'q' any time the keyboard is polled)
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WARNING! This software runs only on 386 compatible processors
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and systems which allow nonaligned word/dword memory access.
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WARNING! This software has no documentation. If you want to use it, you're
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probably a Real Programmer; and Real Programmers don't read documentation.
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WARNING! This software is supplied AS IS. There is No Warranty!
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The software emulates an Intel 8080 CPU (quite accurate,
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except for the halfcarry flag for a couple of instructions)
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and a lot of Zilog Z80 instructions (not the complete set).
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Unimplemented instructions are input/output commands (IN A,(nn); OUT (nn),A;
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INI, OUTI, INIR, OTIR, IND, OUTD, INDR, OTDR, IN C,(r), OUT r,(C)), and
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interrupt mode commands (IM 0, IM 1, IM 2, RETN, RETI), and the refresh
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register doesn't count at all.
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A 486DX2-66 emulates a Z80 clocked at 22 MHz, a 386DX-33 simulates a 6MHz
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Z80. (approximately)
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The BDOS emulator does only provide
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- user 0
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- a single drive (A:)
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- access to lowercase-files.
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A CCP-lookalike command interpreter is provided and the BDOS
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is emulated. The CCP is stored in the file /usr/local/lib/cpm/cpm.sys.
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Any CP/M .COM-files may also go in the directory /usr/local/lib/cpm.
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If you have an original CP/M, with CCP-address e800, BDOS-address f006,
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and put it in the file /usr/local/lib/cpm/cpm.sys, you can have an
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emulator quite near to the original thing, using the -e option.
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The -e option tells the emulator to use the BDOS from cpm.sys,
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instead of catching the BDOS-calls.
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Pros:
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- a real CP/M running
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- access to CP/M-formatted floppies (you have to set the DPB correctly)
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Try "cpm -e -i /dev/fd1" with a 800 KB CP/M floppy in B:
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(bls = 2K, drm = 255)
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after setting setfdprm -p /dev/fd1 800/1200 or the like.
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Cons:
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- no access to the Linux filesystem
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About the emulator:
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===================
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Type "cpm -h" for a short usage message.
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You can interrupt the emulator by typing ctrl-@. This will enter
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the debug mode, where you can disassemble z80 memory, dump memory,
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edit data, set listpoints, breakpoints, set counts for breakpoints
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and the like. Type '?' for a short summary.
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extensions:
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BDOS:
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there is a new BDOS function (41), "change directory"
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and a CP/M program CD.COM which calls this function.
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CCP:
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ERA understands the /Q option (question!)
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Example: ERA *.*/Q
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TYPE understands the /W option (wait!)
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Example: TYPE TEST.TXT/W
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You can access files from other user numbers (image mode only)
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Example: ERA *.BAS/2
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Again: Type UNIX to leave the Emulator.
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TODO:
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=====
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- Improve the emulation of BDOS
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- Allow multiple drives (some as CP/M filesystem images?)
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- implement interrupt modes / signal catching to simulate NMI, INT
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- improve the accuracy of the emulator (but; after all, a Z80 isn't
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8080-compatible as well; the sequence
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XOR A
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DEC A
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JP PO,Z80_installed
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/* an 8080, if we are here */
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will find out...
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- merge the code with xtrs-80, to play GALAXY again!
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BUGS:
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=====
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Surely there are LOTS of bugs. Please send fixes to mbi@mo.math.nat.tu-bs.de
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Bug reports (without fixes) are also accepted, but it would be nice if you
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could track down the bad opcode.
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