IBM 1620 Simulation

jim stephens jwsmail at
Thu Aug 26 21:16:27 CDT 2021

On 8/26/2021 5:14 PM, Ray Jewhurst via cctalk wrote:
> Hello all,
> Long time lurker, extremely rare poster, I was reading the Wikipedia
> article on the IBM 1620 and became quite intrigued.  I know that there is a
> simulator for it on SimH but I have never ran or simulated any card-driven
> machines before.  I have all the documentation and the file
> from bitsavers but I am not sure what to do next.  I know I would like to
> try Monitor, Fortran-II and possibly GOTRAN but I have so many questions.
> I read the SimH documentation which gave me some understanding but I don't
> know exactly how the card decks work, how to install Monitor or how to boot
> Monitor once it is installed since I know you have to boot off a deck.  My
> final question is, is there an easy to use card-driven machine to cut my
> teeth on?  Also, any anecdotes on any of the old IBM computers would be
> both welcome and greatly appreciated.
> Thanks in advance
> Ray
To run from cards, you probably will need to look up the exact keys, but
basically you insert a boot instruction in memory with the machine halted
then run it.

You prepare one of the decks in the card reader prior to that (keep the
SIMH console hand).

The Fortran compiler will need a punch file specified where you can find it,
as each pass will punch cards that need to be successively read in on 
future passes.

I've not run one with a disk or paper tape or other facilities, but the 
reader / punch
/ printer / cpu setup wasn't too hard to run.

Run assembler if you want to study for a while.


More information about the cctalk mailing list