For machine language on TRS80, look at TBUG, and Allen
Gelder's
enhancements thereto.
For assembly, look at Roy Soltoff's assembler
For disk sector work, look at Superzap from NEWDOS80.
I found Superutility (a self-booting disk on the M/M3, but I think it was
a normal TRS-DOS program on the M4) to be very useful for this sort of
thing. I still ahve my M4 sert up to run that. It will let you read/write
any disk that the disk controller is physcially capable of handling.
For disk viewing below the sector level, look at
Roxton Baker's? TRAKCESS.
For disk format conversion, look at Mike Gingel's programs
There was a program called TRScross (or something like that) to read/write
CP/M disks under TRS-DOS. Very useful...
And somewhere I have a program caleld BBCdisk to read/write BBC micro
(Acorn DFS) disks.
For spreadsheets: VISICALC (avail from RS)
For wordprocessing, Michael Shrayer's ELECTRIC PENCIL and RS's SCRIPSIT
There were also other programming langages available. Pascal-80 was wuite
nice (I don;t mean tiny pascal), and MMSforth. I think RS sold Microsoft
Fortran and Cobol.
-tony