Imlac PDS-1 simulators?

From: Bob Shannon <>
Date: Sat Jan 22 08:00:34 2005

There is a fourth Imlac around!?

Does anyone know the state and condition of this other Imlac?

FYI, the Imlac CPU is quite different from the PDP-8, but it does
have many similarities such as the auto-index register locations in
memory, etc.

But being a 16-bit CPU the page size is different (2K words), and
the Imlac has some slightly unusual 11-bit literal instructions (load
with n, and load with complement of n). I don't think those are found
on the -8.

There are some similarities between the Imlac's main CPU and
the HP1000 processors, but this is deceiving, many instruction codes
are the same or similar, but the auctual operations have some differences.

(Dymec studied the -8 when they developed the 2116, but the HP has
additional registers and many more instructions than the -8, or PDS-1).

Moving from HP assembler to Imlac assembler is tricky, its similar but
very different. Becuase of the simplicity of the Imlac CPU it probably
is more -8 like than the HP, despite the direct link between the HP and

----- Original Message -----
From: "Vintage Computer Festival" <>
To: "General Discussion: On-Topic and Off-Topic Posts"
Sent: Thursday, January 20, 2005 4:14 PM
Subject: Re: Imlac PDS-1 simulators?

> On Thu, 20 Jan 2005, John Allain wrote:
>> Interesting all the talk Imlac gets on the list and
>> nothing for either Adage or Evans & Sutherland.
>> Guess it didn't hurt the programmer's console
>> was such a prominent part of the Imlac.
> I think mainly because machines from either manufacture are difficult to
> find. Same with the Imlac, but it just so happens a few people here (Bob
> Shannon, Tom Uban, and myself, plus one other Bob/Robert that used to be
> on the list) are fortunate to have come into possession of the very few
> still existing.
> --
> Sellam Ismail Vintage Computer
> Festival
> ------------------------------------------------------------------------------
> International Man of Intrigue and Danger
> [ Old computing resources for business || Buy/Sell/Trade Vintage
> mputers ]
> [ and academia at || at
> ]
Received on Sat Jan 22 2005 - 08:00:34 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:45 BST