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Compiler behaviour for a32 := a8
by Hans Klaver 13 Feb '21

13 Feb '21

The recent discussions about strings and the OR compiler and how one should interpret the language report reminded me of a question that has puzzled me for some time now. In the change from Oberon (1990) to Oberon-07 the standard procedure COPY(src, dst) was discarded by NW and the type check of the assignment operator := for strings and character arrays was changed somewhat. In Oberon (1990) str2 := str1 was only possible if str1 and str2 were of the *same* type; and COPY could be used if the types were different, truncating a string if necessary. In Oberon-07 str2 := str1 also is possible if s1 and s2 are of *different* types, provided their lengths are *equal*. At least that is how Wirth's OR compiler behaves; at least one compiler (OBNC) still precludes assignment if str1 and str2 are of different types. Now, in Wirth's document 'Differences between Revised Oberon and Oberon' (https://people.inf.ethz.ch/wirth/Oberon/Oberon07.pdf) under '4. Assignment of arrays and records' one can read: '(...) But now we handle array and record assignments just like other assignments, writing dst := src, and discard the COPY procedure. The destination array must not be shorter than the source array. (...)' So I would expect that something like the following should be possible: ... VAR a8: ARRAY 8 OF CHAR; a32: ARRAY 32 OF CHAR; BEGIN ... a32 := a8; (* error: illegal assignment *) But unfortunately this is not possible with the current implementation of the Oberon-07 language. So now we have to use a Strings procedure to get this done: Strings.Copy(a8, a32) (* equivalent to: a32 := ""; Strings.Insert(a8, 0, a32) *) Whereas the following *is* possible when using the OR compiler, which I would regard as not in the spirit of the Oberon language (and that's why I think OBNC has the proper behaviour): TYPE Man = ARRAY 32 OF CHAR; Woman = ARRAY 32 OF CHAR; NoGender = ARRAY 32 OF CHAR; VAR m: Man; n: NoGender; w: Woman; BEGIN ... m := w; (* OR: no error; OBNC: incompatible types in assignment *) n := m; (* OR: no error; OBNC: incompatible types in assignment *) In my view a32 := a8 should be allowed and m := w or n := m not! What do you think? Hans Klaver

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My FOSDEM talk for 2021
by Liam Proven 07 Feb '21

07 Feb '21

It starts at 17:00 CET -- in about an hour and a half from when I sent this email. :-) It touches quite heavily on Oberon and A2. Free to join and to watch. https://fosdem.org/2021/schedule/event/new_type_of_computer/ -- Liam Proven – Profile: https://about.me/liamproven Email: lproven(a)cix.co.uk – gMail/gTalk/gHangouts: lproven(a)gmail.com Twitter/Facebook/LinkedIn/Flickr: lproven – Skype: liamproven UK: +44 7939-087884 – ČR (+ WhatsApp/Telegram/Signal): +420 702 829 053

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7MB echo of comp.lang.modula-2 from 1989 and 1993-1995 and Peter Schweri ArtworkCode 86 in Oberon
by scrutinizer 06 Feb '21

06 Feb '21

While I searched my disk for a backup of Fidonet Modula-2 newsgroup [ "A number of newsgroups are shared globally by FidoNet and the Usenet, e.g. FidoNet's MODULA-2 echomail conference is Usenet's comp.lang.modula2 and ..." -- quote from https://www.fidonet.org/inet92_Randy_Bush.txt ] I found 7 MB of plain ascii text echo of comp.lang.modula-2 from June-1989 and from Feb-1993 to Aug-1995. The keyword 'Oberon' appears more than 2000 times (incuding backquotes in replies). In case this material is no longer available elsewhere and if it is safely considered public domain because it was once publicly available, I'd post it on a suitable webpage. * p.s.: During my search I stumbled upon more material about Oberon: One programming example seems to be alive though the artitst already passed away: http://www.peterschweri.ch/DYNAMICART/continuous-composition-3-4-5.html Is it the following program? ArtworkCode 86 or how to visualize 1296 pictures Visualization is undoubtedly one of the most attractive application of modern computers. In the run-up to Kicking Boxes Billiard- a current exhibition at the Graphische Sammlung of ETH Zuerich that is devoted to contemporary geometric art- we were approached by the artist Peter Schweri with the idea of visualizing his ArtworkCode 86(TM). The basic concept of ArtworkCode 86 is customizable art in the sense that each individual may select his or her specimen from a complete collection of pictures. In its simplest form, ArtworkCode 86 is a set of pictures consisting of 4 x 4 colored double-squares. If (as in the examples below) two colors are used (e.g. black and white, red and green, cyan and magenta) and if the columns are required to be balanced in color (2 double-squares of each color), the complete set consists of 6 to the 4th = 1296 pictures. Essentially, we developed two (trivial) Oberon programs for ArtworkCode 86, one that generates a complete catalogue on a single page in the form of an array of 36 x 36 pictures, and one that displays form-filling any arbitrary picture of the collection (given by its ordinal number). In both cases, the Oberon program produces a portable PostScript(TM) file that may be fed to any PostScript printer or photo exposure device of any size and quality. Thanks to this technique we were able without additional effort to produce (a) a large poster-sized version of the catalogue and (b) high-quality lithographs of some carefully selected pictures. For the interested reader we present the Oberon program that generates the complete ArtworkCode 86 catalogue in green on red. Jürg Gutknecht, Institute for Computer Systems. ArtworkCode 86 is a trademark of Peter Schweri. MODULE ArtworkCode; IMPORT Files, Texts, Display, Oberon; CONST D = 12; H = 8; W = 2*H; dX = 4*W + D; dY = 4*H + D; (*in units of 0.1 mm*) VAR WT: Texts.Writer; col: ARRAY 6, 4 OF BOOLEAN; PROCEDURE WriteLn (s: ARRAY OF CHAR); BEGIN Texts.WriteString(WT, s); Texts.WriteLn(WT) END WriteLn; PROCEDURE WriteInt (i: LONGINT); BEGIN Texts.WriteInt(WT, i, 1); Texts.Write(WT, " ") END WriteInt; PROCEDURE PrintColumn (i: INTEGER; X, Y: LONGINT); VAR j: INTEGER; BEGIN j := 0; REPEAT IF col[i, j] THEN WriteInt(X); WriteInt(Y); WriteInt(W); WriteInt(H); WriteLn("rect") END; Y := Y + H; INC(j) UNTIL j = 4 END PrintColumn; PROCEDURE PrintPicture (N: INTEGER; X, Y: LONGINT); VAR j: INTEGER; BEGIN WriteLn("1 0 1 setrgbcolor"); WriteInt(X); WriteInt(Y); WriteInt(4*W); WriteInt(4*H); WriteLn("rect"); WriteLn("0 1 1 setrgbcolor"); j := 0; WHILE j # 4 DO PrintColumn(N MOD 6, X, Y); N := N DIV 6; X := X + W; INC(j) END END PrintPicture; PROCEDURE Print*; VAR N: INTEGER; X, Y: LONGINT; ch: CHAR; f: Files.File; RF: Files.Rider; T: Texts.Text; RT: Texts.Reader; BEGIN Texts.OpenWriter(WT); WriteLn("%!"); WriteLn("/rect {"); WriteLn("/rh exch def"); WriteLn("/rw exch def"); WriteLn("newpath"); WriteLn("moveto"); WriteLn("rw 0 rlineto"); WriteLn("0 rh rlineto"); WriteLn("rw neg 0 rlineto"); WriteLn("closepath fill"); WriteLn("} bind def"); WriteLn("0.2835 0.2835 scale"); (*to units of 0.1 mm*) WriteLn("90 rotate"); WriteLn("120 -1856 translate"); WriteLn("/Times-Roman findfont"); WriteLn("28 scalefont"); WriteLn("setfont"); WriteLn("0 0 0 setrgbcolor"); WriteLn("0 0 moveto"); WriteLn("(Artwork Code 86 by Peter Schweri) show"); WriteLn("0 -30 moveto"); WriteLn("(Copyright (C) Peter Schweri) show"); WriteLn("180 rotate"); N := 0; X := -4*W; Y := -1622; REPEAT PrintPicture(N, X, Y); INC(N); Y := Y +dY; IF N MOD 36 = 0 THEN X := X - dX; Y := -1622 END UNTIL N = 1296; WriteLn("showpage"); NEW(T); Texts.Open(T, ""); Texts.Append(T, WT.buf); f := Files.New("Artwork.PS"); Files.Set(RF, f, 0); Texts.OpenReader(RT, T, 0); Texts.Read(RT, ch); WHILE ~ RT.eot DO Files.Write(RF, ch); Texts.Read(RT, ch) END; Files.Register(f) END Print; BEGIN col[0, 0] := TRUE; col[0, 1] := TRUE; col[0, 2] := FALSE; col[0, 3] := FALSE; col[1, 0] := TRUE; col[1, 1] := FALSE; col[1, 2] := TRUE; col[1, 3] := FALSE; col[2, 0] := FALSE; col[2, 1] := TRUE; col[2, 2] := TRUE; col[2, 3] := FALSE; col[3, 0] := TRUE; col[3, 1] := FALSE; col[3, 2] := FALSE; col[3, 3] := TRUE; col[4, 0] := FALSE; col[4, 1] := TRUE; col[4, 2] := FALSE; col[4, 3] := TRUE; col[5, 0] := FALSE; col[5, 1] := FALSE; col[5, 2] := TRUE; col[5, 3] := TRUE END ArtworkCode.

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RISC5: memory instructions and flags
by Hellwig Geisse 06 Feb '21

06 Feb '21

Hi all, I'm currently testing my re-implementation of the RISC5 system, which I carefully constructed to be consistent with its defining paper "The RISC Architecture" https://people.inf.ethz.ch/wirth/FPGA-relatedWork/RISC-Arch.pdf This document doesn't say anything about setting the condition flags when executing memory instructions. Consequently, my design of the CPU does not touch the flags during load and store instructions [*]. As it turns out, this does not work with the current Oberon compiler. Let "run" be a BOOLEAN variable. Then the condition within the statement "IF run THEN ..." is compiled to MOV R0,0x00000000 LDB R0,R0,+0x0001C BEQ 00FFE550 which only is correct if LDB sets the zero flag according to the data loaded. NW's RISC5 implementation does exactly that. Now, who is right? May the compiler rely on the fact that the condition flags are set on a load? Then the definition of the RISC5 instruction set must be changed. Or is the CPU entitled to load data without setting the flags? Then the compiler must be updated. Hellwig [*] Setting the flags during load/store instructions is *very* unusual in RISC designs because the data path from the memory to the register file usually does not go through the ALU, so no chance to set the flags.

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Re (2): Re (2): Starting V4.
by peter＠easthope.ca 05 Feb '21

05 Feb '21

From: =?utf-8?Q?J=C3=B6rg?= <joerg.straube(a)iaeth.ch> Date: Fri, 5 Feb 2021 10:10:31 +0100 > Unfortunately, PO2013 does not foresee an „automation“ hook in > the code. Understood. PO has carefully chosen capabilities and limitations. N.W. takes his computers seriously! In recent months I've been learning a little about V4. After years using ETH Oberon, comparison with V4 is almost inescapable. > Date: Fri, 5 Feb 2021 10:42:05 +0100 > I had a look at the code of System.Mod in Linux V4 1.7.02. There, I > find an automation/configuration hook in OpenViewers: It tries to load > the module „Configuration“. It is expected that the module body > does all things you want to automate/configure additionally during > startup. > > If the module Configuration is not found, the text file System.Tool is > opened instead. Good, thanks. Now I can stop wondering about more complexity in that direction. Eventually might improve https://en.wikibooks.org/wiki/Oberon/V4#System_Configuration . For sake of interest, more indulgence in comparison. =8~) ... InitCommands is only one section in Oberon.Text. By adjusting and recompiling a few modules, InitCommands can be omitted. NetSystem is another section that most users will engage. I understand that network configuration can be compiled in. The tradeoff is three steps to change configuration (edit, compile, test) versus two steps (edit, test) with Oberon.Text. I accept that you might prefer compilation. Also that Pieter Muller might prefer Oberon.Text. As with InitCommands, network configuration could be compiled with the NetSystem section of Oberon.Text omitted or ignored. I'm no authority on this tradeoff but have an impression that compiled configuration is good for an embedded system. Design and build an embedded system and never change it. There is no intention for a user to monkey with a configuration file and cause unexpected difficulties. In a workstation or a high performance data acquisitor/processor as Wojtek visualizes, frequent adjustments of configuration might be necessary. Then text (or Text) based configuration is convenient. In any case, clear documentation tends to be worthwhile. Regards, ... P. L. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re: [Oberon] Re (2): Starting V4.
by peter＠easthope.ca 05 Feb '21

05 Feb '21

From: "Skulski, Wojciech" <skulski(a)pas.rochester.edu> Date: Thu, 4 Feb 2021 16:45:53 +0000 > Do not forget the command line parameters which are also a form of > configuration. Acknowledged; but must the user execute them interactively at each boot up? Can commands be executed automatically when the system boots? Regards, ... P. L. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Re (2): Re (2): Starting V4.
by peter＠easthope.ca 04 Feb '21

04 Feb '21

P.s. From: Joerg <joerg.straube(a)iaeth.ch> Date: Thu, 4 Feb 2021 07:57:10 +0100 > it seems to depend on what version of V4 you look at. Definitely. > In the Init procedure of Configuration.Mod ... No Configuration.Mod in this Linux V4 1.7.02. > In the Init procedure of Configuration.Mod you can put all your > desired commands you want to run during boot. Eg. > - set your preferred color scheme > - set the working directory > - open System.Tool > etc. Given the spartan style of PO V5, configuration in compiled source is understandable. ETH Oberon and V4 are more conventional workstation systems. ETH Oberon has configuration in Oberon.Text. So I question whether V4 was meant to be configured strictly from compiled source. Possible but it seems rather odd and a difficulty for novices. Regards, ... P. L. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Re (2): Re (2): Starting V4.
by peter＠easthope.ca 04 Feb '21

04 Feb '21

Joerg, From: Joerg <joerg.straube(a)iaeth.ch> Date: Thu, 4 Feb 2021 07:57:10 +0100 > Sorry, it seems to depend on what version of V4 you look at. > I just checked with the V4 on Windows, there the boot sequence seems to be different. Thanks for checking the details and reporting. I've added a brief note at https://en.wikibooks.org/wiki/Oberon/V4#System_Configuration . If and when there is time, I'll study this more and write more complete notes. For Linux at least, a fresh release with details analogous to the Windows release will be appropriate. Regards, ... P. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Re (2): Starting V4.
by peter＠easthope.ca 04 Feb '21

04 Feb '21

Joerg, From: =?utf-8?Q?J=C3=B6rg?= <joerg.straube(a)iaeth.ch> Date: Wed, 3 Feb 2021 22:14:40 +0100 > In PO, the file „System.Tool“ is opened in System.OpenViewers (this is hard coded) Thanks. > In V4, the file „System.Tool“ is opened in System.Init. If valid > commands exist in the file „System.InitCommands“, then these > command are executed instead. Here I have V4 1.7.02 in Debian Linux. http://olymp.idle.at/tanis/oberon.linux.html Neither System.Init nor System.InitCommands is present. Also no Oberon.Ini, although a copy from the Windows release was sent to me. Appears that some bolts were omitted when 1.7.02 was assembled for Linux. I'll aim to find, install and execute an earlier version. Might find more there. Ideally, I should make a complete release and put it on Sourceforge. The opportunity might be some time in the future. =8~/ Thanks for the help, ... P. L. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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Re (2): Starting V4.
by peter＠easthope.ca 03 Feb '21

03 Feb '21

As installed, Native ETH Oberon and the Oberon subsystem in A2 have command "System.Open System.Tool" in Oberon.Text > InitCommands. If Oberon.Ini in V4 is the analogue of Oberon.Text in ETH Oberon I expect to see "System.Open System.Tool" in Oberon.Ini. Not there. Nevertheless System.Tool is opened. Has anyone found "System.Open System.Tool" Thx, ... P. L. -- Tel: +1 604 670 0140 Bcc: peter at easthope. ca

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