IBM 1620 Simulation

Chuck Guzis cclist at
Thu Aug 26 20:46:08 CDT 2021

On 8/26/21 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.

Cards are just ASCII lines separated by newlines>

For more information, see:

It's been years since I used the SIMH 1620 simulator, so I can't even
claim to be remotely current.  I used it to check out some sample code
back then.

My reaction:  It's just not the same.  I guess you had to be there.

Did anyone manage to snag a copy of Monitor IID?  Or is the only extant
version Monitor I?   The differences were significant.

Also, don't forget SPS!

If you're new to the 1620, I recommend the following book:

If you want to use a totally (i.e. no disk) card-driven version of the
1620, I'd recommend that you start with simple machine language
programs.   I (dimly) recall that using the card-only FORTRAN compiler
was a bit of a chore:  read pass 1, read your program, while punching an
intermediate deck, read pass 2 and the intermediate deck, read the
subroutine library and wind up with an executable deck.


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