MEM11 Status Update

Kip Koon computerdoc at
Sun Aug 30 00:16:13 CDT 2015

Hi Guy,
Hello!?!  What is the MEM11 Board and are there other boards to make this a fully functional PDP11?  I definitely want to know!  Thanks in advance.

Kip Koon
computerdoc at

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Guy Sotomayor
> Sent: Sunday, August 30, 2015 1:06 AM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: MEM11 Status Update
> I'm making good progress on the MEM11 firmware.  I spent the last few days re-doing the firmware build environment.  Previously, it
> would build all the files each time.  Now there is a proper Makefile (even though it takes about a minute to build everything).  I
> realized that I needed something better than what I had because there are multiple targets (emulator, FPGA eval board and the
> MEM11 board itself).  Right now I'm focused on getting as much debugged on the emulator since it has a reasonable debuging
> environment.
> I've also integrated various test programs into the build environment and use various low level code as part of the main firmware for
> hardware access.
> This "kills two birds with one stone" since it tests not only the various hardware functions it also allows me to debug some of the
> firmware separately from the full code base.
> At this point, the emulator fully supports all of the J1 instructions (and they all work too!).  In terms of I/O (that will be part of the
> MEM11 board) it supports LEDs and various configuration inputs, FRAM, UART and timers.
> The biggest risk that I'm taking is that the UART is emulated as being directly exposed.  On the MEM11 hardware, the UART will be
> connected through a SPI interface which requires that all accesses to the UART are asynchronous transactions.
> The biggest piece of work remaining on the emulator will be emulating the Unibus interface.  The work here will mainly to create a
> means to script various Unibus transactions.
> However, before doing that, I'll be testing out the boot loader code and the configuration firmware since none of that is dependent
> upon the existence of functional Unibus hardware.
> TTFN - Guy

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