ISO: Motorola MDP-1000 info/software

ED SHARPE couryhouse at
Wed Sep 30 05:12:57 CDT 2020

Josh I posted   photo  of  a manual  we  had   a long  time  but  not  too long if  you  want  to search  the   cctalk  here.. Also  always  wondered  which  plant built in... is  this  same   basically as  a  pbp 8  or   is  it  just that  they are both  12 bits?  Thanks  Ed# In a message dated 9/29/2020 11:26:36 PM US Mountain Standard Time, cctalk at writes: 
Hi all -- This is a long shot, but I was curious if anyone might have information onthe Motorola MDP-1000 minicomputer.  I picked one up recently and I'mworking on restoring it.  Of particular interest is the power supply, whichis external to the processor and which I am missing.  I think I have thevoltages worked out (+/-5V and +/-15V), but there are a number of othersignals on the power supply connector that I'm unsure of at the moment. I've put a few pictures up here:!Aqb36sqnCIfMpIVYmzKjFnsT3nHh8w?e=b2iqqv I'll note that this isn't technically an MDP-1000 -- it's labeled as anMDP-6650 on the rear.  I suspect that this is a ruggedized version of the1000 intended for harsher environments.  The front panel of mine appears tobe identical to the drawings of the MDP-1000 in the manuals I have. It also came with a binder of documentation (but alas no schematics) thatI'll be scanning soon and getting off to Al.  It's an odd little system --5 12-bit registers, a 12-bit ALU, and a 12-bit Instruction Register, butthe memory is 8 bits wide.  Instructions are packed into two bytesnormally, but there's a special 64-byte region of memory that can be usedto store "shared bytes," which allow encoding certain instructions into asingle byte, taking the other byte from the shared region.  I've never seenanything quite like this.  I wonder why they didn't just use 12-bit widememory... Also the process for using the front panel to examine and deposit memory isinsane.  Here's the instructions for reading a memory location; it's 10steps.  Depositing is 17.!Aqb36sqnCIfMpIVWThgwlxgCMQo59A If anyone has anything on this, let me know.  Not expecting much, but it'sworth a shot.- Josh

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