TRS-80 Model II/12/16

Fred Jan Kraan fjkraan at
Fri Dec 31 12:16:22 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.
I have the 8 meg disk system:, but still 
haven't found time and space to properly test it. Replaced some blown 
capacitors, but that is all sofar. The authorative source for most 
things TRS-80 is Frank Durda's site: 
The original 8 Meg controller emulated the WD1000 chipset even before it 
was on the market. So it should look like something familiar :-).

Fred Jan

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