TRS-80 Model II/12/16 (was Re : HP Drives)

Tony Duell ard at
Thu Dec 30 15:11:27 CST 2010

> Yeah... I've been steadily working towards getting a working TRS-80 
> Xenix machine. At the moment, I have enough parts (I believe) to make a 
> working Model II, and a line on the 68000 board. Unfortunately, the 
> difficult part to find is a hard disk. I have the Model II host adapter 
> for the early TRS-80 Eight Meg drive (which is, of course, completely 
> incompatible with anything else), but no drive. I can't even cobble it 
> to a regular MFM drive, since the actual disk controller is in the drive 
> cabinet (I have only the host adapter). Unfortunately, you can't really 
> run Xenix without a hard drive. 

I wonder...

The Model 1/3/4 hard disk system consisted of a WD1001 controller board, 
a disk drive and a very simple host adapter (just an address decoder 
really). I would not be suprised if the M2 one was similar in concept.

Radio Shack were also very good about supplying technical/service manuals 
(one reason I liked their machines, yes even back then I knew the value 
of a schematic!), so I suspect some information on the M2 hard disk 
system exists. 

I wonder how hard itwould be to make up a devie to plug into the host 
adapter, appear to have the smae M2-accessible registers, but using some 
mode modern storage device. Probsbly a lot easier than replacing an ST412 
hard disk, for example.


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