


Subj: (MOD III HARD DISK INFO)

There is quite a bit to it:
You will need:

1. hard disk unit 
2. Western Digital Controller:  WD-1000 series including 
   WD-1000, WD-1001 or WD1002 unit (Apparat used the 
   WD-1002-05 controller). 
3. Host adapter to decode hard disk controller registers to 
   TRS-80 (Z-80 port) as follows:
    a. Z-80 (TRS-80) ports 0C8H - 0CFH to respective WD-100
       x register.
    b. port 0C0H to latch circuit to indicate WRITE-PROTECT 
       status (not to controller:  00 = not Write-protected.)
    c. port 0C1H:  used for hard disk reset, may or may not exist!

I suggest the following:

1. Western Digital data sheets on controller 
2. Some description of ST-506 hard drive interface 
   standards/specs
3. Technical reference material on TRS-80 Model III 
   expansion bus.

If there is enough interest, I'll try to develop so more detailed information.

