|
DataMuseum.dkPresents historical artifacts from the history of: CP/M |
This is an automatic "excavation" of a thematic subset of
See our Wiki for more about CP/M Excavated with: AutoArchaeologist - Free & Open Source Software. |
top - download
Length: 16384 (0x4000)
Types: TextFile
Names: »REZ.O$«
└─⟦7de604eb8⟧ Bits:30003308 REZ disassembler til RC700
└─ ⟦this⟧ »REZ.O$«
REZ A disassembler for 8080 programs by Ward Christensen as modified for Z-80 with TDL mnemonics by William Earnest with Zilog mnemonics by Hank Kee CP/M U.G. 1/80 Suggestions? Call me eve's at (312) 849-6279 W. Earnest is at (215) 398-1634 ---------------- REZ commands are inconsistent at best. - REZ is a kludge based on years of disassembler experience and hacking, and was never "planned" - just coded sitting at a tube, and modified over 2 years before being contributed to the CP/M UG. For example, to kill a symbol: k.label but to kill a control value: caddr,k and to kill a comment: ;addr, but REZ does the job like no other I have seen. ---------------- N-O-T-E: Pardon the editorial, but I feel hardware without good software is useless to 99% of us. Most good software has to be paid for. I strongly support the legitimate purchase of licensed software. I do not regularly use any programs which I have not purchased. (Yes, I do occasionally "try" one, but then buy it if I plan on using it). I have been asked by software businesses to NOT distribute REZ - because of it's ability to produce good .asm source quickly. But, there are so many disassemblers out, why not a good, conversational one? Please use it in the spirit in which it was contributed: to enlarge your understanding of the micro- computer world around you, and to allow you to customize programs which you legitimately own, for your own use. "Semper non rippus offus" ---- NOTE: any command taking a hex address (Dnnnn, etc) may take a value in the form .label but arithmetic may not be performed. (i.e. d.start is ok, but d.start+8 not) ---------------- Overall structure of REZ: It is a .COM file, which runs at 100H. It goes thru 1B00 or so, then the stack. At 1C00 is a 512 entry table for control commands. Each is 3 bytes long, and controls the format of the re-sourced list, i.e. is it .BYTE, .WORD, .BLKB instructions, etc. At 2200 is the start of the symbol table. It has no defined length as such. If it is not used, it occupies only 2 bytes. If you want to re-source something which is in memory, such as a PROM, a program previously loaded in high memory, "CP/M itself", or whatever, you can just do so. However, typically you want to disassemble a program which runs at 100H, which is were REZ runs. Bob Van Valzah would have solved that by making resource relocatable and moving itself up under BDOS. I wasn't that industrious. Instead, REZ uses the concept of an "invisible" OFFSET. After all, what do you care where it is as long as it LOOKS like it's at 100h? So, you set an offset. O2F00 sets it to 2F00 Hex. Reading a .COM file (RFOO.COM) causes it to come into 3000 on. If you say D100 or L100 it dumps or lists what LOOKS like your program. Internally, REZ is adding the offset to the D and L addresses. What should you set the offset to? Well, that depends upon how many symbols you will use. O2400 will load the program at 2400, thus allowing only 2200-23FF for symbols, i.e. 512 bytes or about 50-60 labels. If you didn't leave enough space, then used B to build a default symbol table, the table could run into and clobber your .com file! (easy recovery, however: just change the offset to being higher, and read in the .COM file again) Each entry takes 3 bytes + the symbol length, and if you like 7 byte labels like I do, that means 10 bytes/label. An offset of 3300 should be adequate. If you want to put comments into the disassembled program, you will have to designate an area to Use for the comments. The U command (e.g. U4000) specifies what area is to be used. Before issuing the O (offset) command, do: L5 7 which will show the JMP to BDOS, which is the highest memory you may use. (Note if you have, for example, an empty 4K memory board in high memory, you can Use THAT for comments). Let's take an example: You have an 8K file, FOO.COM which you want to disassemble. It will have about 300 labels. 300 x 10 is 3000, or call it 4K (what's a K unless your tight). The symbol table starts at 2200. 4K more is 3200. Let's load the .COM at 3200, so since it normally starts at 100H, the offset is 3100. O3100 is the command. We then RFOO.COM to read it in. It says 5200 2100 which means it came into actual memory to 5200, but 2100 if we are talking with respect to loading at 100. Thus, we could set our comments table up after the .COM program - say at 5400: U5400 The ? command shows the memory utilization for control, symbol, and comments entries. (no, I never put in anything to keep track of the .COM - you'll just have to do that yourself). If you ever want to dump real memory, you'll have to reset the offset to 0: O0 but then set it back. If you are not sure what it is, typing O will tell the current offset. Hoo, boy! Hope this kludge of documentation is enough to get you going - hmmm, better give you some of the gotcha's I've discovered... ---- WATCH FOR ---- * Symbols overflowing into the .COM. (Use ? command to see how full symbol table is) * Control entries overflowing into .SYM (altho I can't believe anyone will have a program with more than 512 control entries!!!) * Comments overflowing into BDOS (ug!!) * Using an offset which is not in free memory and overlaying BDOS or whatever. * The B(uild) command gobbling up too much when building a .BYTE: "B" will take a .BYTE 'GOBBELDY GOOK' followed by LXI H,FOO and take the LXI as a '!' (21H) so you'll have to manually stick a new "I" control entry in at the address of the LXI. You might also delete the incorrect "I" entry which REZ stuck in (typically at the second byte of the LXI) * Trying to dump real memory without setting the offset back to 0. (then forgetting to set it back to its proper value) * Forgetting how big the .COM file you are disassembling was. * Using REZ to rip off software (yes, I know, you heard that before, but only 3 in 100 needed to be told, and 2 in 100 needs to be told again, and 1 in 100 doesn't give a rat's fuzzy behind anyway!!) * Forgetting to take checkpoints when disassembling large files. You may even want to rotate the names under which things are saved: STEMP1.SYM STEMP1.CTL STEMP1.DOC * Missing a label: Suppose you have a control entry for a .WORD, resulting in: DFLT: ;172C .WORD 100H but somewhere in the program, the following exists: LDA 172DH Even if you did a B and have a label L172D, it won't show up since it's in the middle of a .WORD. Instead, do this: K.l172d kill the old label e172d,.dflt+1 put in the new label as a displacement off the beginning. * improperly disassembling .WORD's (see previous item). You might be tempted to make DFLT a .BYTE so that DFLT: ;172C .BYTE 0 L172D: ;172D .BYTE 1 Note that while this disassembles and reassembles properly, it is not "as correct" as the technique used in the previous item. * Having the "B" command overlay your "E" control entry. What? Well, "B"uild is pretty dumb. If he finds 8 .BYTE type characters in a row, he fires off a .BYTE from then on until he runs out of those characters. Suppose your program was 200 long (ended at 3FF), and you had zeroed (aha! Nice .BYTE candidates) memory there (there meaning at your offset address + whatever). Then you QB100,400 and viola!! REZ overlaid your "E" control with a "B". ---------------- REZ is relatively complete. (well, actually, the phrase "rampant featureitis" has been "mentioned"). ...But there's always another day, and another K... SO... Here's my "wish list" ..it might save you telling me YOU think such-and-such would be nice... * Targets of LHLD, SHLD should automatically be flagged as type .WORD in the control table. Ditto LDA and STA as .BYTE or as second half of .WORD. Ditto targets of LXI as .BYTE (?). * E5C,.FCB followed by E6C,.FCB+ should automatically calculate the appropriate displacement, and put it in the symbol table. * The comments facility should be enhanced to allow total SUBSTITUTION of entire line(s) of the code, i.e. at address such-and-such, replace the next 3 bytes with the following arbitrary line. This would help those "how do I explain what was being done" cases such as: LXI H,BUFFER AND 0FF00H * Add the ability to, in one instruction, rename a default (LXXXX) label to a meaningful name. ---------------- REZ types an "*" prompt when it is loaded. You may then enter any of the following commands. Each command is a single letter followed by operands. Commas are shown as the delimiter, but a space will also work. ---------------- ---------------- ; Put comments into the program. (must execute 'u' command first, to assign area for comments to be placed) ;addr,comment enter a comment ;addr lists existing comment ; lists entire comments table ;addr, deletes existing comment note that 'Ø' is treated as a new line, i.e. ØtestØ will be formatted: ; ;TEST ; ---------------- Attempt to find .BYTE's while listing the program. - This command works just like 'L', but attempts to find .BYTE's of 8 chars or longer. (see 'L' command for operand formats) ---------------- Build default sym tbl (LXXXX) labels for each - 2 byte operand encountered. Note 'B' is identical to 'L' except labels are built. (see 'L' command for operand formats) ---------------- Control table usage: - c dump ctl tbl cnnnn dump from starting cnnnn,x define format from nnnn to next entry. values of x: B = .BYTE (attempts .ASCII if printable, 0DH, 0AH) W = .WORD (attempts label) S = .BLKB to next ctl entry I = instructions K = kill this ctl entry E = end of disassembly NOTE every control entry causes a "control break" (NO, REZ was NOT written in RPG) which means a new line will be started. Thus if you have a string in memory which disassembles as: .BYTE 'Invalid operand',0DH .BYTE 0AH You might want to change it putting the 0DH,0AH together on the second line - just enter a "B" control entry for the address of the 0DH. The same technique could be used to make .ASCII 'TYPESAVEDIR ERA REN ' appear as .ASCII 'TYPE' .ASCII 'SAVE' .ASCII 'DIR ' .ASCII 'ERA ' .ASCII 'REN ' ---------------- dump: - dxxxx Dumps 80H from xxxx on daaaa,bbbb Dumps from aaaa thru bbbb d,bbbb Continues, thru bbbb d Continues, 100H more NOTE 100H is the default dump length. If you have a larger display, you can change the default via: d=nn nn is the HEX new default. For example, a 16 line tube could display 80H: d=80 or.. d=80,200 Defaults to 80, dumps 200-27f ---------------- enter symbol: - ennnn,.symbol symbol may be of any length, and contain any char A-Z or 0-9, or "+" or "-". This allows: E5D,.FCB+1. Note the "+" is not checked, i.e. E5D,.FCB+2 would be wrong (assuming FCB is at 5C) but would be allowed to be entered. Note if you enter two symbols for the same address, whichever one is first alphabetically will show up on the disassembled listing. If you have a label which has the wrong address, you need not explicitly kill the old one before entering the new. A label which is spelled exactly the same as an existing one will replace the existing one even if the addresses are different. ---------------- Find occurrence of address or label. Note this function - runs until interrupted (press any key). fnnnn,ssss find address nnnn in memory. Start the search at ssss. Runs forever. Press any key to stop. f continue previous find command fnnnn find nnnn starting at address you last stopped at in the f command ---------------- kill symbol from table - k.symbol ---------------- list (disassemble). This command is used to list the - file, or to list it to disk after enabling the .ASM file save via 'SFILENAME.ASM' command l lists 23 lines from prev pc lssss,eeee lists from ssss to eeee l,eeee lists from current pc to eeee lssss lists 23 lines at ssss Note that if you have a control 'e' entry, then the list will stop when that address is found. This allows you to 'lstart,ffff'. The 23 line default may be changed via: L=nn where nn is a HEX line count, e.g. L=0f set to 15 lines/screen You can change the default and list, e.g. L=9,100 Dflt to 9 lines, list at 100. NOTE when using L to list the .ASM program to disk, you should either list the entire program at once using: Lssss,eeee or, you can list small pieces at a time. As long as you list again without specifying a starting address, (L or L,nnnn) then the output file will continue uninterrupted. You may do dump commands, and others, without affecting what is being written to disk. ---------------- offset for disassembly - o print current offset onnnn establish new offset (note the offset is always added to any address specified in an a, b, d, or l command. to dump real memory, the offset must be reset to 0 (O0) before the dump.) ---------------- prolog generation - this routine generates an - .LOC instruction, and equates for any label outside of a given low-hi address pair. (the start and end addresses of your program). e.g. if disassembling from 100 to 3ff, it will generate 'fcb = 5ch' if FCB is in the symbol table. In typical use, you would 'sfilename.asm' then use the P command to write the prolog, then the L command to write the program itself. Pstart addr,end addr quiet command: any command which is preceeded by a q - will be done 'quietly'. For example, to save a .asm program, you could just do: ql100,3ff or ql100,ffff if you have set the 'e' control in the control table. Another use is to build a default symbol table by taking a pass thru the program: QB100,xxxx ---------------- read .com, .ctl, .sym, or .doc file - rfilename.com reads in at offset+100h rfilename.ctl loads the ctl table rfilename.sym loads the sym file rfilename.doc loads the comments table (note 'u' command must have been issued) ---------------- save .asm, .ctl, .sym, or .doc file - sfilename.asm use 'l' command to write, z to end sfilename.CTL saves the CTL table stablename.sym saves the sym file sfilename.doc saves the comments table ---------------- use area of memory for comments table - unnnn such as ud000 if you had an open board at 0d000h ---------------- purge sym tbl and CTL tbl x - ---------------- close .asm file (note that a preferred way to close the .asm file is to have specified a control entry for the end address (e.g. c1ff,e)) z - -------------------------------------------- -------------------------------------------- Here is a sample of the REZ usage. Given: a COM file (lets say test.com) which runs at 100 (as any good COM file should), and goes thru 2FF. lines preceeded with ---> are typed by you. ---> REZ ---> o2600 set the offset to 2600, which means the program will read into 2600 + 100 = 2700. ---> rtest.com reads the com file into memory. system says: 2900 0300 which is the actual hi load addr, (2900) and the original hi load addr (300) REMEMBER this address (300) because you might want to put a "E" (end of assembly) control entry there. <<<<note>>>> that all 'L' (disassembly list) and 'D' (dump) commands work with the offset added. Thus, you should learn to forget that the disassembler is in memory, and think of it as if your program were actually at 100. D100 will dump your program. also note: if the program being "REZd" will have a fairly large symbol table, then you will have to set the offset higher: o3300 or some such. (the ? command will show symbol table usage: if your symbol table is nearing the .com file, then just set a new offset (higher) and re-load the .com) if you want to dump r-e-a-l memory, you would have to reset the offset to 0: o0 (but don't forget to