MEM11 Status Update (Guy Sotomayor)

Guy Sotomayor ggs at
Tue Jan 20 18:48:59 CST 2015

On 1/20/15 4:42 PM, Michael Thompson wrote:
>> Date: Mon, 19 Jan 2015 21:27:59 -0800
>> From: Guy Sotomayor <ggs at>
>> To: cctalk at
>> Subject: MEM11 Status Update
>> As some of you know I've been working (on and off again) a
>> multi-function Unibus board that contains all of the more difficult
>> items to allow a PDP-11/20 to run Unix V1 entirely within the CPU
>> chassis.  Other than the CPU and the RK11-D controller, everything else
>> will be on the MEM11 board.  Here's the background on what the MEM11 is
>> and the current progress.
>> What's on the board is the following:
>>    * Up to 124KW of non-volatile memory
>>    * Console Emulator ROM
>>    * 4 Boot ROMs selected from 32 images on the board
>>    * 2 DL11 SLUs
>>    * RF11 controller with non-volatile memory emulating 8 RS11 drives
>>    * KE11 EAE
>>    * KW11K
>>    * KW11L
>>    * KW11P
>>    * KW11W
>> TTFN - Guy
>> ******************
> I am working on a similar project for the Omnibus. I am connecting a
> Microsemi SmartFusion FPGA to the Omnibus, and doing the peripheral
> emulation in a combination of the FPGA and Linux running on the ARM
> Cortex-M3 hard core in the FPGA. Anything with timing restrictions goes in
> the FPGA. Everything else goes in Linux as a combination of a device driver
> and an application.
> For simplicity, I am starting with programmed I/O devices, with the paper
> tape reader/punch first. I should be able to add serial ports, printer
> ports, analog I/O, diskettes, card reader, and maybe DECtape. Later I will
> add data break (DMA) and add disks and mag tape. I am planning to keep the
> disk images in flash, load them into RAM and run from there, and save them
> back to flash if the processor is halted.
> The MI8E bootloader wiggles the same Omnibus signals as the front panel. I
> could have the FPGA do the same, and load any one of a selection of
> bootloaders.
> I am not adding memory, because a nice 32kW RAM board already exists.
An Omnibus version of the MEM11 (slightly different device set 
obviously) is also on my list of
things to do too...I have a long list of projects like this.  Just not 
enough time to get them done
right now.   You know, that whole work thing where you get paid. ;-)

I avoided ARM because I wanted the "firmware" to be really lean and 
mean.  What I have on the
MEM11 isn't much leaner.  ;-)

TTFN - Guy

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