Supported OUT-files of ZX Spectrum emulator 'Z80' versions 3.02 and 3.03 by G.A. Lunter.
OUT-file is a sequence of five bytes blocks. First word in each block is time in Z80 processor tacts (range from 0 to 17471). Second word of block is ZX Spectrum port address. And last value of block (byte) is data was sent to this port during this tact.
Each 17472nd tact in any case one block is wrote into OUT-file, and if during this tact no outing to any port of Speccy then first word of block is 65535. One tact of Z80 processor equal to 1/3494400 sec in 'Z80' emulator.
OUT-file can contain outing either to any Speccy ports or to selected ones. To record outing only to AY-3-8910 ports (#BFFD and #FFFD), adjust 'Z80' emulator for storing only one port: #FD, and after creating OUT-file, convert it via Ay_Emul to some other format (for example, ZXAY-file is optimized analog of OUT-file).
'Z80' and 'Z80TRDOS' emulators (version 3.02 and 3.03 tested) has sad error. As known, during port outing OUTD and OUTI commands data is outed to port BC, after that register B decreased by 1 (and BC by 256). 'Z80' writes to created OUT-file wrong port address (decremented by 256).
If player uses standard AY port addresses (#BFFD and #FFFD), the error is masked, because of new addresses are equivalent to standard ones and Ay_Emul play that OUT-file rightly.