RX02 drive emulation (was RE: Lisa Profile Drive emulation on a PC) - test-drb@ccmp.vtda.org

11 Nov 2000

From: Eric Smith &lt;eric(a)brouhaha.com&gt;
...

I don't have documentation, so I'm not disputing that, but this
makes me very curious.  How is it that the RX8-E card (M8357) can deal
with any of:

1)  RX01
2)  RX02 in RX01 mode
3)  RX02 in RX02 mode 

The board has dual interface modes.  The RX02 has multiple modes
as well.  The best way to no results is to try a RX02 in a Qbus box
with RX01 controller.  Made that error once, wasted a lot of time
even though it hurt nothing.

...
 From the standpoint of building a machine from the ttl
ground up the RX01 drive controller is a great example of what can be done 
with little.

Instruction set is:

    WBS    (wait, branch, stall IO)
    DO   (do pulse, xx,xxxx bits)  
    JMP  (to field X)
    CBR    (conditional branch)

It's mildly horizontally code and also verticle coded.
Uses 74181 (x2) for the 8bit alu and a pair of 7489s
for registers.  instruction word is 8bits.  Ran fast 
enough to decode/encode FDC data in real time. 

Allison