UZ80 is a freeware Z80 assembler that aims to be both small and fast while still providing valuable services such as macro instructions and conditional assembly. Internally, it departs from full two-pass methods and relies instead on assembling as much code as possible during the first pass and writing down the lines making references to still unseen symbols; these lines will be assembled when all symbols are known.

20180326-1155: third public release. Escape sequences look for errors. Added synonyms SUB/AND/XOR/OR/CP A,PARAM for SUB/AND/XOR/OR/CP PARAM. The UZ80 Win32 binary is no longer packed.
20180322-1930: second public release. Added instructions OUTD and OUTI (synonyms of OTD and OTI) and fixed inconsistencies when using a macro with fewer parameters than defined.

20180408-1440: fourth public release. Buffers are now dynamically allocated and reallocated, "out of memory" should happen only when no more memory can be allocated. Several fixes in error handling: word overflow no longer labels itself as "byte out of range"; error messages during final calculations are shown only once; opcodes relying on small constants (BIT, IM and RST) perform consistent range checks.

20180414-1140: fifth public release. Removed synonyms OTD and OTI. Code cleanup: source is 48k, binary is 32k.

20180426-1030: sixth public release. Added synonyms LD BC/DE/HL,BC/DE/HL for LD C/E/L,C/E/L+LD B/D/H,B/D/H. Fixed illegal commands LD XL,L/H/(IX) and similar being accepted. INCLUDE swaps '/' and '\' when required.

20180510-1255: minor patch fixing a bug in source paths with folders.

20180808-0946: eighth public release. Added "[" and "]" as indirect addressing symbols: LD A,[HL] is equivalent to LD A,(HL). Bugfixes: added dummy instructions "list" and "nolist" to ease compatibility; command line parameter "-vv" returns the right exit code rather than always 1, and "-oX" without source doesn't crash any longer; source line "label:opcode" defines the label and assembles the opcode rather than handling it as a very long label without any opcodes.

20180910-1020: minor patch fixing a bug in DEFB ("a"+1 was rejected despite the equivalent 1+"a" being valid and accepted) and making command line options case-insensitive.

20181025-1445: minor patch accepting the lines "label=expression", "label= expression" and "label =expression" as valid synonyms of "label = expression" rather than handling them as a very long label or rejecting them as improper labels or opcodes.

20181104-1105: minor patch fixing a bug that raised errors in lines that had more than one parameter whereby the first one included a symbol not yet defined, but the second one didn't, and 256 symbols had already been defined.

20190731-2140 -- UZ80 is now GPL. Upgraded GCC to 5.1.0.
20190210-1150 -- minor source cleanup setting apart PSEUDO and OPCODE; RST accepts 0-7 as well as 0-56, in the same fashion JP (HL/IX/IY) could also be written JP HL/IX/IY; changed IN 0,(C) and OUT (C),0 into IN (C) and OUT (C) because whether the byte sent by OUT is 0 or 255 depends on the Z80 CMOS/NMOS type.
20181130-2030 -- minor patch fixing a bug where HY was a synonym of XH rather than YH, adding further synonyms HIX, HIY, LIX and LIY for XH, YH, XL and YL respectively, and restoring optional AS80 compatibility with command line parameter "-$" to emulate the bugs "IX-1-1" = "IX-0" (rather than "IX-2") and "lbl db $-lbl,$-lbl,$-lbl" = "lbl db 0,0,0" (rather than "lbl db 0,1,2").

20190928-1055 -- ninth public release. Added command line parameter -Ipath to define an optional INCLUDE path; fixed bugs in the handling of expressions within brackets and commas within quotes, and in INCLUDE with very long command line paths; made a couple of errors slightly more explicit. Code cleanup: source is 50k, binary is 32k.

20200103-1105 -- tenth public release. Added AS80-compatible shortcuts LD BC/DE/HL/IX/IY,BC/DE/HL/IX/IY (i.e. LD HL,BC generates LD H,B + LD L,C) and extended the behavior of INCBIN to handle negative parameters as relative to the end of the file (i.e. INCBIN "FILE",-10,8 seeks the ten last bytes of the file, reads eight and ignores the last two) rather than to its beginning.
20191010-1925 -- minor patch adding two optional parameters to INCBIN to define the file offset and length.
20191003-2020 -- minor patch adding the pseudo instruction INCBIN, identical in syntax to INCLUDE, but taking the specified file as binary data rather than as source code.

20200331-1155 -- minor patch simplifying operand priority calculation and macro local labels and making some errors more explicit again, such as ORG telling apart between "undefined symbol" and "invalid expression".