16 Nov
2013
16 Nov
'13
11:20 a.m.
I've been away from my addiction^H^H^H^Hhobby for a 3-4 years now, but
this summer I got rid of my
old consulting office and moved everything into my living room
(temporarily :-)
Since the move I've been slowly trying to clean up old projects.
One of them was the udisk disk controller emulator.
In 2006-2008 I build a 4 layer prototype. The PCB had some flaws on the
power plane, so I had to add a lot of wires for power but it basically
worked. It has an ARM (atmel sam7s) and a CPLD on it as well as
"correct" Unibus interface hardware. In 2008 I dabbled with it but
never really got it stable. It would barely boot RT11.
This fall I finally got serious. I dusted off the board and plugged it
into my 11/34a. I used a logic analyzer and an arm jtag pod and really
debugged it. I fixed a bunch of little issues in the CPLD state
machines and cleaned up the arm code to be "correct" and took out all
the hacks. The result is it's stable now and appears to be working
correctly. The bus transactions look correct and clean.
As a result, with RL02 emulation I can now boot all the images I have,
which include RT11, RSTS V7.2, XXDP 2.5 and BSD 2.9. I also did an RK05
emulation, which used to work but I have not tried it again. I will
shortly.
I am itching to try bigger disks, so I might try a MSCP, we'll see.
Those 2Gb CF disks... And I should run the XXDP diags on the
controller. That should be interesting.
I updated the docs on http://www.heeltoe.com and included the source
code for the firmware as well as the CPLD rtl and testbench. I also
updated the schematic pdf.
My plan is to do a little more testing and then fab another 4x PCB's;
Hopefully this time I won't botch the gerbers and the power plane (which
is split 3 ways) wont' be completely disconnected (which is better than
completely shorted, I might add, something I've also done once :-)
It's been a fun project. I was tempted to update it but I think it's
fine as it stands. All of the parts are available via digikey, which is
one of my 'rules'. A lot more could be done with the firmware. The
CPLD has a tiny amount of wiggle room, but it's pretty full.
Going forward I plan to do some interface projects with the "mojo" FPGA
board, like a pertec tape emulator and a RL02 emulator, just for fun,
but I wanted to finish this up first.
Once I have the new boards working, I plan to make up 2 "loaner" boards
- I'll like someone with an older machine like an 11/05 or an 11/70 or
11/45 to try them out if they are game. And if of course I'm willing
to sell them at basically cost if anyone wants them. With small quanity
pcb runs the PCB's tend to be the most expensive part. I think the PCB
+ parts was about $300. As I recall I have new unibus interface chips
for about 5x boards. I also have a number of scrap boards which I think
I can use to "harvest" interface chips. I could also check the gray
market again, who knows.
-brad