In my reading to try to learn about the disk layout, directory, and boot process of TRS-80 Model I and Model III, I see some unusual words come up again and again.

Along with the common terms "track" and "sector" there are also the unusual words "granule" and "lump".

My guess is that one of these must be Tandy's dialect for "block". But which? And then what could the other possibly mean?

1 Answer 1


OK, this is very dusty material in my memory, so I'm relying a bit on Google/Wikipedia here. I may be able to find some of my printed documentation, but it will take a while.

The granule was the allocation unit for the filesystem. I don't remember the granule size on single-density drives, but Wikipedia says for double-density drives it was 6 sectors per granule, 3 granules per track. (Single-density drives had 10 sectors per track, I think, so probably 5 sectors per granule.)

It looks like lump was a term specific to NEWDOS/80, which I never used. It appears to be one level higher than the granule; a lump contained multiple granules.

Both were logical divisions, as opposed to the mostly-physical sector and purely-physical track.

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