SIMH LGP-30 Progress.

B Degnan billdeg at
Tue Feb 10 23:03:11 CST 2015

Update on my attempts to bootstrap the SIMH Royal Precision Electronic 
Computer model LGP-30. 

I have been able to get through a lot more of the simulator-equivalent 
processing steps to match the input of the bootstrap programs via the 
native Flexowriter.  I have been able to discover the syntax and basic I/O 
via trial and error, and a lot of reading.  I believe that loading the 
bootstrap manually is a must; one cannot use or create tapes otherwise.  
Most SIMH's have some kind of software guide, the LGP-30 has none.  I don't 
think this SIMH has the bootstrap pre-loaded.  I am unaware of anyone who 
is using the SIMH simulator, although I have seen two non-SIMH LGP-30 
simulators.  One is in German. 

In order to enter instructions into memory I first learned how to translate 
code from the various actual papertape sources, for example...   

"flexowriter entry"> 6300 P 0000'  


sim> d -a 6300 10000000  

where 6300 = memory loc in drum memory, 1000 = P, 0000 = accumulator 
address (?).  You can't store a "P" or "p" in memory.  You have to convert 
to its Flexo binary equiv.  Same goes for all instructions in the LGP-30 
repertoire.  The hardest part is finding ways to enter Flexowriter key 
input via a modern keyboard, using SIMH commands. 

It's all pretty slow going to patch together what I think would be a 
workable bootstrap install process, but I expect to have to try a number of 
variations before I get any response from the machine.  I have a bootstrap 
but the hard part if the Flexowriter emulation.  Who knows, maybe I will be 
able to contribute a software guide from all of this.  I will document what 
I find and post on my web site,  



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