This web site collects bits and bytes to be shared with other people. One of my interests is computer emulation of both new and old hardware systems. From the sixties, Honeywell's 16-bit minicomputers are taken as start. A 12k DDP-516 was the first computer I ever worked with and determined my working life to a large extent. Now, being retired after working 40 years in ICT, there is time to play with computers just for fun and to explore subjects for which there was no time before.

Spending time to old computers may look worthless in that context. However for young people it is hard to imagine how the ICT discipline, and how fast that discipline developed over the past 50 years. Computers of 50, 40 years ago were very different from the small boxes we have today. Not only the size was different, also their capabilities and costs have hardly any relation to what we call computers today. Also the software, the development tools, the languages were primitive compared with today's standards.

May be caused by the fast development of the computer industry over the last 50 years and the shake out of so many computer companies during those years, much of that development looms to be forgotten. Hardware and software of the past may be labeled today as primitive. It is however good to understand that many of the developments at that time were milestones on the way to get the computer systems as we have them today.

The interest in computer history is growing. Sites on the web start to collect bits and pieces of the information systems of the past in order to contain some of those exiting milestones. One milestone was the creation in the sixties of "the minicomputer": a relatively small and low cost box at that time, with a real computer in it.

Introduction

This site is about the software simulation of the 16 bit Honeywell DDP516/316 (sold by Philips as P9202/P9205) and the Philips 16 bit P800 minicomputers. In addition to that, software and documentation for both can be found on this web site. Collecting (and restoration of) software and documentation for these computers is an ongoing effort and is / will be published step by step.

Also the result of rebuilding these mini's with an FPGA (Field Programmable Gate Array) is / will be published. This provides me the opportunity to learn a new technology to build hardware. And, by using it for rebuilding a machine I worked with say 40/50 years ago, it also is a nice illustration of Moore's law. In less than 50 years, cabinets with logic circuitry disappear in the corner of a small chip which only costs a few dollars, while the old, well known programs are still able to run.

Honeywell Series 16

Machines of the Honeywell Series 16 computer line, starting with the DDP-116, were the first (may be the first) minicomputers that used 16 bit words, which size became the minicomputer standard. Most of its (later disk oriented) software is lost, but due to efforts of some people active on the web, a large part of its standard paper tape software is still there. This software, together with a working hardware emulator of the DDP-516/H-316 machine, gives the possibility to get a flavor of a "state of the art" minicomputer of the mid-sixties. Part of this web site is devoted to that subject.

DDPx16 Pages

Simulation of the DDP-516/H316

Philips P800 Series

Philips Electronics marketed the Honeywell 16 bit machines (OEM, as P9200 range) until Philips came in 1971 with its own minicomputer line, the P800. Reflecting the state of the art of 1970, machines of this family had a much more sophisticated set of features and software than for instance the Honeywell machines which reflect a typical minicomputer design of the sixties. Although the P800 became a popular building block in many different types of systems, there is nothing (.. almost nothing) about these systems on the Web. Is everything about these systems really gone ??

I worked with P800's during the period 1972-1980 and only still own a few documents describing the instruction set and some programs. In November 2007, when my first version of a P855/P860 simulator was published, this text finished with the remark: "I am interested to make a P800 emulator and have some prototype working, but unfortunately software is completely lacking". This remark was followed by the question to contact me in case of sharing interest in the P800 machines or having either documentation or software available for these machines. This yielded a few interesting reactions with as result that some of the original P800 software (and documentation) popped up, which can now be made available in combination with the simulator. So happily the situation (end 2008) is much better than a year ago: with original P856 software there is now a working simulator prototype of the P856, while the P855/P860 is improved. Whether the P855/P860 simulator will work as the real one is of course still unknown, because original software for that machine is still lacking. But having the P856 working with some of its original software is a major step forward and the results will be successively published on this web site.

Please contact me in case of sharing interest in the P800 history, its technology and software, or in case of having some of its software or documentation. Not everything is lost yet; but may be some other software (for the P855/P860 for instance) pops up from one of the dark corners, where we put items without value anymore. Would be nice and, who knows, may make it possible to add a few other bits to the history of computers.

Most wanted P800 items:
- A (pdf of) P800 Macro Processor Manual (MAC) (Load Module is available)
- Original P855/P860 software (to validate the P860 simulator)

  ** Any help to recover one of these items is highly appreciated; please contact: info@theoengel.nl **

P800 Pages

P855/860 Simulation

P856 Simulation (most recent P856 simulator version is 0.045 Feb 26 2017)

P85x Simulation (P853/4, P858/9 and MAS)

RTL/2

The Rise and Fall of Philips Data Systems

This is the title of a recent ebook publication (2023/2024) about the computer division of Philips Electronics. The Swedish authors Mats Danielson and Arne Läppinen give a nice overview of part of the European computer history. Especially the Sweden and The Netherlands parts of the company are highlited, as well as the France part of the company, where the P800 minicomputers were developed and produced. Really interesting stuff!

Download free Ebook

Rebuilding a Mini with an FPGA (Field Programmable Gate Array)

Summer 2009 I discovered a, at least for me, new technology that looked to be excellent for rebuilding a historic computer. I knew about FPGA's predecessors, like PLA's, but those could only be used with specialized tools and just for a part of the logic of a computer. Apparently also the progress in that area is big: to my surprise, FPGA technology is affordable now for hobby use at home and can be programmed with a common PC. Promising: the threshold to start using this technology is low! But where to start? No idea how big an FPGA should be to contain the logic of a mini; no idea how to program logic, which programming language to use, how to connect peripherals, etc., etc.

So although it is easy to consider to start using an FPGA for rebuilding an old mini, it quickly turned out that there is to beat a learning curve. Half a year later now (January 2010) the results of my experiences are that far, that I got the idea to add them to this web site, as an other technique and addition to the software emulation of old computers. Is this called hardware emulation ?

The first fruit of my efforts is a working rebuild of the Honeywell 316/516 and because it did not falsify my first expectations of this challenging technology, others will follow. For details, please look at the link below. Being a first exercise, improvements are certainly possible, so feedback will be appreciated.

X16 FPGA implementation

The second exercise is a FPGA implementation of one of the members of the P800 family of Philips Minicomputers: a P856. In addition to supporting a console typewriter and a papertape reader and puncher, this implementation supports two moving head disk units by using the SD-card of the FPGA development board. Loaded with original P800 software, the DOS operating system, including Assembler and Fortran, is running from the SD-card.

P856 FPGA implementation