Next project: 11/24. Does it need memory?

Chris Zach cz at
Mon Oct 19 19:20:35 CDT 2020

On 10/19/2020 6:10 PM, Noel Chiappa via cctalk wrote:
 > Time to stop trying random things and drop the (metaphorical) Big
 > Hammer.

Well, yeah. Although my methods are *not* random, what I have been doing 
is trying to set the 11/24 and it's peripherals to a known working base 
state. Unibus can get annoyed at a lot of things (lack of termination, 4 
kinds of Unibus (well 5 if you consider the 11/45), and a whole lot of 
general weirdness.

Q-Bus is much simpler, although there is 18 and 22 bit and the weird CD 
interconnect to watch out for, you don't need a terminator and with very 
few exceptions (RKV11, RL01 dual controller, very early memory that 
wanted external refresh) things pretty much work bus-wise.

 > "Internal addresses; i.e. serial line unit registers .. There is no
 > external bus cycle performed for an internal address."

Yeah, the serial ports I think are emulated-ish on the main board. If I 
could disable them I could do a normal DL11 and see what I see, but that 
won't work. Maybe I'll just drag out the 11/05 and get that working 
first, it's got a nice front panel that doesn't lock up often :-)

But if someone has an 11/24 and can cross-check my switch settings to 
see if I missed something I would appreciate.


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