Messing with the Monitor

The 68000 Microprocessor (5th Edition) Hardcover – Nov 25 2003
by James L. Antonakos (Author)

So I was trapped in the Library for a bit, and spied this book. It’s not every often in 2019 you are going to find books about the 68000, as I’m sure any good library will have removed stuff like this, and have it pulped ages ago. But the amount of current technical books in English here is pretty damned slim to none, so I was all to happy to pickup this book for a week.

The poor thing has been checked out 4 times in the last 15 years. I guess the kids don’t know what they are missing.

Anyways what was interesting in this book is that it has a CD-ROM, and on there is some lesson code from the book, along with an assembler that outputs to S-records of all things, and a small emulator that is meant to be compiled under MS-DOS. It was trivial to isolate the passing of DOS interrupts from Unix/MinGW and get the simulator running on something modern.

In Chapter 11 there is a brief walkthrough on building a board, which sounds like fun although I’m sure in 2019 finding parts will be.. challenging, along with a simple monitor program.

The built in assembler can happily assemble the monitor, but it’s geared for talking to the obsolete hardware as specified in the book. I just made a few small changes to instead have it’s console IO hook to the simulator’s TRAPs and I had the monitor running!

I then took the echo test program, and modified it to run at a higher location in memory, along with exiting via the RTS instruction, so that it will exit when you press Q back to the monitor. Then for the heck of it I further extended the monitor so you can Quit it, and return to the simulator.

Is this useful? I’m pretty sure the answer is absolutely not.

The CD-ROM is tiny, I thought it would be packed with goodies, but it’s 250kb compressed.

The68000MicroprocessorFifthEdition.zip

If anything people using this book will probably have lost the CD-ROM and want the programs.

  • ISBN-10: 0130195618

And my horrible changes here.

Wasting some cycles on FrontVM

Frontier!

A while ago I had chased FrontVM to moretom.net and found 2 links. One from 2003 which is a dead link, and the 2004 version which was archived by the wayback machine!

It was an interesting build, as it still used 68000 emulation from Hatari/UAE this pre-dates the 68000 to C or i386 ASM. However since it ran (mostly) the original code, it was more ‘feature complete’, although loading save games is broken for some reason (I think the decryption was not disassembled correctly). It was actually a stupid file mode setting. I just updated the source & put out a new binary, testing save games between Linux &Windows.

Anyways, it originally built on Cygwin, so I filled in the missing bits, and have it building on both MinGW & Visual C++

Parked outside Willow in the Ross 154 system

So yeah, it’s Frontier, for the AtariST with the OS & Hardware calls abstracted, still running the 68000 code under emulation. I think it’s an interesting thing, but that’s me.

I put it and the other original versions I found over on sourceforge.net

Download Frontvm

Oddly enough it’s already been downloaded, so go figure.

Multiplayer Macintosh Plus via Javascript/

I found this fun page over on retroweb.maclab.org  What is interesting is that it encorporates PeerJS and WebRTC to allow for a virtual network, letting you play multiplayer AppleTalk.  Just enable the network, and scan for other users.

It’s pretty cool, in a zero config kind of way!

PCE-MacPlus

And for coolness it’ll embed in a snazzy picture of a Mac Plus.  Although you can magnify the screen, so you don’t have to squint so much.

MachTen 2.2

MachTen console

Not that I need another UNIX, but I came across this fine thing googling around for some Mach based OS’s running on the 68000, and well here is MachTen.  Perhaps the most notable thing about MachTen is that it is capable of running in usermode under MacOS.  Without a MMU.

# cc -v hi.c -o hi
gcc version 1.40
 /usr/local/PMtools/cpp -v -undef -D__GNUC__ -Dunix -D__MACHTEN__ -DMACHTEN -DTENON -D__unix__ -D____MACHTEN____ -D__MACHTEN__ -D__TENON__ -Dmc68000 hi.c /var/tmp/cc000093.cpp
GNU CPP version 1.40
 /usr/local/PMtools/cc1 /var/tmp/cc000093.cpp -fno-builtin-alloca -fno-defer-pop -quiet -dumpbase hi.c -version -o /var/tmp/cc000093.s
GNU C version 1.40 (68k, MIT syntax) compiled by GNU C version 2.3.3.
default target switches:
 as -mc68000 -o hi.o /var/tmp/cc000093.s
 ld -o hi -x /usr/lib/crt0.o hi.o -lc
# size hi
text    data    bss     dec     hex
11220   400     1672    13292   33ec
# ./hi
hello!

And yes, it even supports TCP/IP with it’s own TCP/IP stack.  It can even operate as a router of all things!  From a users point of view it is a little sparse, but it’s 4.3BSD, and thankfully includes the C compiler, so unlike of UNIX of the era on ‘small hardware’ this one isn’t crippled.

configuring TCP/IP

TCP/IP is configured through the MacOS via the control panel.  As you can see it can use AppleTalk, Ethernet and TokenRing interfaces.  For my simplicity, I’m just using SLiRP on the Ethernet, so it’s the old 10.0.2.15/24 setup.  I re-compiled my BasiliskIII to redirect a port into the VM so I can telnet into it.

To install System 7.0.1 you need to set Basilisk II / Cockatrice III as a IIci. I went ahead and used this ROM.  The ROM however does expect there to be a FPU.

rom Mac-IIci.ROM
modelid 5
cpu 2
fpu true

Running however, I’ve been able to set the CPU to 3 or 4 (68030/68040) and it’s fine, I think the major thing is the modelid.  If I try this under System 8 which needs a 68040, then it’ll crash in spectacular ways.  You don’t need MacTCP as again MachTen is a 4.3BSD kernel with Mach 2.5, so it has it’s own.

MachTen also includes support for NFS!  This greatly eases getting data in & out of the system.  To mount my Synology I just need the following command:

mount -t nfs -o timeo=1,retry=1,rsize=512,wsize=512,retrans=1 192.168.1.3:/volume1/Data /mnt/data

And I’m good to go!

Cross GCC from Windows to AmigaDOS

GCC 2.7 to AmigaDOS 2.04

GCC 2.7 to AmigaDOS 2.04

Yes, I know there are others.  Newer versions of GCC too!.. but I was more so curious to see if I could do it.  I know there were GCC 1.x ports to the Amiga but I can’t find source anywhere.  And for some reason the Amiga and Atari ST seem to have never been mainlined into GCC.  I would have thought 1990-1992 they would have had far more users than say SUN-2/SUN-3.

Some ‘fixes’ are described in this file:

https://raw.githubusercontent.com/sdenel/How-to-install-SimpleScalar-on-Ubuntu/master/Install-SimpleScalar.sh

Although it’s not 100%.

I downloaded the files mentioned on this GCC page, and started to massage stuff.  This was easier as GCC 2.7 & Binutils 2.8 both support Windows NT 3.5 (and much much higher!).

I may want to try to get an ancient Nethack to build, so I put it onto sourceforge…

win32-amigados_hello.7z

I’ve just tested a hello world type executable.  I’m more so amazed that it linked and executed, ‘file’ detects the objects as

x.o: raw G3 data, byte-padded

But at least the executables look right:

hi: AmigaOS loadseg()ble executable/binary

I had to hack all kinds of crap compiling eamiga.c
and eamiga_bss.c as neither generated correctly, and both had all kinds of missing and undefined things.  I’m sure on bigger projects it’d just explode, but right now I’m just amazed the linker could pick up my object, plus the 21 year old objects + libraries from that aforementioned ancient GCC port.

Oh well I was entertained for a couple hours.

Dungeon 2.5.6 on MacOS

Years and years ago I had bought this copy of Language Systems Fortran for MacOS with the intention of using my Quadra to build Dungeon for MacOS.  Except I couldn’t figure out the first thing about MPW, and life was always busy and I never did figure it out.  Well after getting GCC to compile something on MacOS, I thought I’d dig up some images I made of the disks, and without the benefit of having the manuals anymore see if I could figure it out.

FORTRAN Dungeon 2.5.6 on MacOS

FORTRAN Dungeon 2.5.6 on MacOS

And much to my amazement it compiled without any real issues.  All the EOF markers in the files had to be fixed up, and gdt.f for some reason was mangled at the end, but it was trivial to repair.  I didn’t bother trying to integrate the gettime call, so the clock and any clock events don’t work correctly.  I guess I should make the seconds increment by 15 between calls, or something.  Oh well I don’t think anyone will really care.  I compiled it for the 68020 with 68881 hooks, although I doubt it even makes any calls.  It runs for me.

If anyone cares, the binary is here:dungeon-2.5.6-m68k-MacOS.sit

As always, you’ll have to read the 404 screen to get the download.

GCC 1.37 on MacOS

I didn’t even know there was such a thing!

But sure enough, the file GNUMPW.SIT, and the later gcc-1.37.1r15-all.sea.bin are the real thing!  The file GNUMPW unstuffs to GCC 1.37.1r7(All), although Stuffit 5 and higher won’t unpack the file, I’ve converted it unpacking with version 4 & repacking with 5.5.

The readme from r7 is dated November 2nd, 1990.  I found some history on this port on the archives of the GCC mailing list here.  The port was done by Stan Shebs, while working for Apple.  As he states the port started in 1989 and was first used in an abandoned m68k based project, and later a possible replacement for the Apple compiler for OS 7.

For this experiment I was using the r15 version, as I didn’t find anything out about the prior versions until after I had written this.

GCC on MacOS needs the MPW environment, which for me is incredibly awkward to work with. While some people may love it, it is very strange in that you have to highlight commands in the window, then hit clover+enter to run them.  Like a mainframe, you can input commands wherever in the screen.

The next hardest thing was finding a version of MPW that will work with this.  It needs the MPW C compiler for it’s includes, and libraries.  The 3.5 stuff didn’t seem to work for me, however doing a LOT of searching, and I did find a ‘toast CD-ROM’ image‘ of 3.1 that includes all the C, and Assembler tools that I need to build an executable.

I also don’t know why, but running make just shows me what needs to be done, it never actually makes anything.  I’m probably doing something wrong, but for such a long dead tool, trying to find out how to use it, or how do you interrupt a “stream” like manually running cc1 is beyond me.  I just have to force quit the emulator.

But beyond that, running make gives me the steps, and I manually select and run the steps, and I was able to get a program to run!

xxx

sieve

I know it may not look like much, but getting it to actually run something was quite monumental for me!

I thought for the hell of it, I’d try to build the InfoTaskForce 1987 interpreter, but it seems to get confused at the whole input method.

Planetfall on MacOS

Planetfall on MPW

There were some issues compiling input.c, as it didn’t like the external table, so I made it’s own local table.  It also didn’t like some pointer arithmetic, but making GCC happy only gives me a program that can’t recognize any verbs.  And from there it won’t quit, basically hanging the system.

I’m sure I’m doing something wrong, but at the same time it was interesting to see GCC on MacOS, during the whole GNU boycott of Apple for the ‘look and feel’ lawsuit against Microsoft.  No doubt it let a lot of people sell other C compilers on the Mac Platform during this window of time.

GCC requires a 68020 processor, as GCC’s native 68000 based target would be SUN-2 hardware.  While it can compile with the -m68000 flag, I haven’t tested with a 68000 based emulator to see if that’s even true.  In the off chance someone wants a combined MPW+GCC I made a disk image here: MPW 3.1 with GCC 1.37.img.gz.  Disk Copy 6.3 should be able to mount it OK, or any emulator that likes HFS disk images.

More fun with GCC 6.1

So after looking at the -Ofast flags in that utterly unfair GCC 1.4 vs GCC 5.1, and 6.1 , I thought I’d try to build Cockatrice III with it.  Everything went well, and I had a build in no time.

I always hated how I had to massively downsample the audio so I could at least hear things, so I thought I’d try to put them back to 44100Khz, 16bit stereo.  And while compiling, older GCC runs fine, while 6.1 throws this run error!

../SDL/audio_sdl.cpp:57:43: error: narrowing conversion of '-1404829696' from 'int' to 'uint32 {aka unsigned int}' inside { } [-Wnarrowing]
 uint32 audio_sample_rates[] = {44100 << 16};
                                           ^
makefile:104: recipe for target 'obj/audio_sdl.o' failed
make: *** [obj/audio_sdl.o] Error 1

Well it turns out that it’s getting truncated as the audio_sample_rates are defined as an unsigned int, but it really want’s to be a regular integer.  So I changed the type, and now I have high def audio!  While I was in there, I fixed some stupid typos in the keyboard so I can actually use vi in MacMiNT.

It’s still in 256 colors, I’m missing something fundamental as to why it’s not working but I just don’t have enough time to mess with it today.

For anyone who cares, the Win32 binary package is on sourceforge.

UAE’s 68000 core actually was once in MAME

I was kind of surprised to find it.

While I was looking for System16 stuff, I found the first version of MAME to include the UAE 68000 core starting in release MAME 28, although System16 emulation itself didn’t appear until MAME 33b3, but not playable until MAME 33b4.

So what does it mean?  Well at the time the UAE core was the way to go.  However from looking at the MAME source, the UAE core that they were using from System16 was already generated, while UAE still included the build68k program to parse the tables, and generate the 68000.  Instead they were editing the outputted C.  UAE wasn’t GPL until version 0.7(something), 0.7.6 for sure, so I don’t know why they weren’t using it from the source.

Eventually starting in MAME 35b2, the core was replaced with MUSASHI , so Among their reasons for dumping the early UAE CPU core was this laundry list:

  • New 68000 C core. For testing purposes, this is also being used in the DOS
    version instead of the asm core. [Karl Stenerud]
    Differences:

1. Faster. This code is, barring ram fetch time, almost twice as fast as the existing C core in MAME. I’ve done extensive speed profiling on both engines. The only problem now is the slow memory access in MAME due to bankswitching et al.

2. Emulation more correct. I found many bugs in the MAME engine (and many, many more in mine for that matter) when I pitted them head-to-head. I have run random instructions from each opcode class at least 10 million times, comparing the resultant CPU states, and have left it running random instructions for 1 billion iterations. In every case, I have adhered to the specs defined in M68000PM/AD REV. 1.

3. Disassembler is correct. The current M68000 disassembler in mame has a tendency to disassemble instructions that have an invalid EA mode.

4. Cycle counting is 99.9% correct. The only instructions which don’t have correct cycle counts are divs, divu, muls, mulu, and they’re not worth counting correctly. (I’m not about to waste emulation time counting 0-1 and 1-0 sequences).

5. > 32 bit friendly. I’ve taken care to ensure maximum portability without sacrificing speed. The result is conditional compiling dependant on your architecture. I’ve also implemented and tested a compatible solution for architectures that lack 8, 16, or 32 bit signed storage types.

6. The code is carefully laid out to be readable.

Also in MAME 35b4 added in was emulation of the NEC uPD7759 chip for speech, fleshing out the System16 emulation.

To compile these ancient versions, and inbetween I was using my Candadian cross DJGPP GCC 4.12 Win32 cross compiler.  For Allegro I’ve always found it builds far easier using GCC 2.7.2.1, a vintage compiler from back in the day I could just run in DOSBox.

Alien Syndrome

Alien Syndrome

Obviously with today’s machines, these ancient versions of MAME run fine on DOSBox!  It’s really amazing in the scope of emulators running emulators.

I found the source code to UAE 0.4

Kickstart in colour!

Kickstart in colour!

Wow what a change from UAE 0.1!  We now have colour, mouse and keyboard input, so we can finally interact with the machine.  Behind the scenes the biggest change of course was the ‘Heroic effort’ of rewriting UAE from C++ into C.  It certainly made reading the code much more easier as nothing is implicit, like it is in C++.

From the changelog between versions 0.3 and 0.4:

960203 filesys.c, action_read(): Slightly more efficient code (translate Amiga
address to real pointer).
Moved some common code in the generate_* functions in gencpu.c to a
separate function.
960202 Added an experimental fast disk option. Currently turned off by
default (it's not such a big win).
Attached sprite fixes (overlapping att. sprites looked bad, Katakis).
Add sleep(1) before resetting the console to text mode when using
SVGAlib: this might fix some screen corruption problems.
Add sprite/playfield priority checking to the most important case
(single playfield, no HAM).
In filesys.c, do_find(): open() returns -1 on error, not zero.
Return ERROR_OBJECT_WRONG_TYPE if do_find() is called for a directory
(fixes Champions of Krynn harddisk installation).
960201 Don't abort if sound driver not present, just set produce_sound to 0.
New files keybuf.c and keybuf.h to record keypresses in the right
order and without losing any. In cia.c, force 15 scanlines between
keypresses, just to be sure.
unixfs.device does work with Kick 1.3: just don't trust what Kick 1.3
sends in the startup packet. For now, disable more than one mount per
command line.
Started integrating Ernesto's new Mac sources.
Remove superfluous includes from some files.
960131 Added Ed's unixfs.device (great stuff).
Adding ULONGs to pointers is a bad idea on the Alpha if the ULONG value
really is signed. Add some casts to LONG in (pc_p + src) expressions
in genpu.c.
If DMACON is written and copper DMA is enabled, do a COPJMP1 at once.
Helps the "Interference" demo.
960129 More SGI fixes from Ed. Bugfixes and transdisk improvements from Marcus
Sundberg.
Remove EXTRA_DEFINES from Makefile. Breaks some systems.
Move common sprite code from pfield_doline() and pfield_doline_slow()
to new function pfield_sprite(). The same sprite may appear more than
once on the same line, so don't shift out the bits of sprdata[] and
sprdatb[] while displaying it (Turrican I).
In xwin.c and svga.c, barf if LINUX_SVGALIB doesn't match the file
being compiled.
Make all .o files depend on config.h in the Makefile.
No need to exit if sound driver unavailable, but -S given.
Small debugger fix: Missing space in output.
Fix for the sprite logic: Specifically, use a state variable indicating
whether the sprite has been restarted after a VSYNC. Fixes most
Turrican problems.
960124 Added Denis Sablic's patch for sound run-time option.
Added Ed Hanway's patch for better Makefile, X mouse cursor blanking
and more SGI compilation fixes.
960123 Include options.h everywhere.
Handle 8 bit GrayScale visuals like PseudoColor.
Remove C++ leftovers from joystick code.
960122 When using the joystick driver, the button test must come after
handle_events() in vsync_handler().
960118 Removed all the remaining C++ comments. Changed all inline keywords to
inline. Define inline if not using gcc.
Make proper prototypes for everything. Compile with maximum warnings +
-ansi + -pedantic.
Remove CIA_cycle(), obsolete.
Reimplemented the STOP optimization in newcpu.c. Removed DualCPU
support in CPU emulator.
Real nasty bug in pfield_doline() fixed: sprxpos could be evaluated as
negative, with not-so-amusing results. (Need to rewrite this in
Oberon to get array bounds checking :-)
960117 Heroic effort: Rewrote the thing in C. This might help fix some
problems with users being unable to compile it.
Fixed a problem in hsync_handler(): Only call flush_line() for lines
in the display window, i.e. when we did a prepare_line() before.
Better code for relative branches: Don't use setpc(getpc()+x) calls,
increment regs.pc_p instead.
960116 Reimplemented the function to load the Kickstart ROM. Use stdio instead
of fstreams since this apparently does not work on the Mac. Detect 256K
Kickstarts. Detect corrupt ROM images (calculate checksum).
Added Ernesto Corvi's Mac port. Changed it around a bit, so it
probably won't compile.
960115 Reinstate config.h options for X screen depth, so that DrawPixel() can
be inlined in custom.cc for speed. xlinebuffer is now incremented in
each call to DrawPixel() (for both X and SVGAlib) to get rid of some
address calculations.
960114 Fixed X generic pixel drawing routine for SHM.
Still trying to fix the harddisk emulation.
uae.device no longer breaks the debugger (can step through uae.device
functions now)
Bugs affecting performance: SPCFLAG_STOP never got reset, and DSKLEN()
would set SPCFLAG_DISK even if DMA was being turned off.
Made slow memory a run-time option.
Defer interrupts by one CPU instruction to give programs a chance to
read INTREQR ("Seeing is Believing" and "Substance" demos)
Added ScrollLock hack for X, too.
960113 SVGAlib version compiles again. Fixed SVGAlib mouse bug.
Fixed SHM bug: Maximum scanline is 313, not 312.
Sometimes, disk.cc missed a side change and would read the wrong data.
Fixed. Apparently, this was the worst compatibility problem.
Implemented trace mode.
960112 Changed layout of class amigamemory a little so that gcc can generate
better addressing modes.
Finally wrote functions in gencpu to generate MOVEMs.
960109 Integrated Ed Hanway's patches for better X support and run-time
configuration of some options.
Got rid of the direct VGA memory access. (Need to do this differently).
Changed the method of drawing lines: custom.cc now tells the graphics
code the line number and whether it needs to be doubleed before drawing
it.
Added Andre Beck's MIT-SHM patch.
Remove warnings for newcpu.cc.
960108 Fixed exceptions in op_illg(): Need to decrement PC.
960107 Added an "uae.device" resident module at 0xF00000. This emulates a hard
disk (fixed size 8MB for now).
960106 Moved some common code from pfield_doline() and pfield_doline_slow() to
a separate function. This fixes a potential HAM bug (two static vars
for the same value).
Sound support for Linux. Works only with graphics off and the CPU
slowed down.
Better SVGAlib keyboard support.
960105 Added AvailMem(), AllocMem(), AllocAbs() and FreeMem() dummies.
The Hardwired demo times the multiplication instructions and prints
"This demo don't like Axel" if they are too fast. Apparently, Axel has
a 68040. Added a WANT_SLOW_MULTIPLY option to config.h.
Fixed the fast blitter emulation (seems to work now).
960104 Fixed all the ChangeLog entries from 95 that said 96 (oops??!)
pfield_may_need_update() should check whether bitplane DMA is on.
Added ersatz.cc and ersatz.h. The purpose of these files is to
implement one or two Kickstart functions that are commonly called from
bootblocks. This should help support some games and demos that only use
the Kickstart as an initial track loader. So far, it's only good enough
for one program.
951223 More intelligent event handling in the CPU emulator. Slightly faster.
951222 Optimize CPU emulation by inlining cctrue(). Also, the real PC no
longer needs to be incremented each instruction. The real PC value
now has to be fetched by m68k_getpc().
Added direct screen access for SVGAlib, but it didn't help much. I'll
probably remove it again.
The gencpu executable is 2M smaller if it allocates memory
dynamically.
951216 custom_bput() enhanced a little. Now remembers the value that was
written in the other half of the register.
Apparently, the USEx bits of BLTCON0 are ignored in line draw mode.
(Silents-Demo)

At this point it really does work.  However a machine of 2016 compared to 1996 is just too fast.  As a result it is once more again unusable.  But it makes sense that code from this era would be built to run as fast as possible, however when it really can run fast, watch out!

I found this code while trying to find other older versions and found a post about uae-0.4.hqx, as the hqx suffix denotes that this was the Macintosh port, which thankfully included all the source, and it looks like it pretty much left the source to UAE intact.

It didn’t take much to modify the xwin.c module into a suitable module for SDL, and I was able to get it running on Linux, and with a simple re-compile onto Windows. I did amputate the filesystem sharing code.  I could fix it I guess, but considering the insane speed of 0.4, it really doesn’t matter.  If you want to test it, simply copy a 512KB kickstart to “kick.rom” and copy an ADF diskette image to df0.adf, and start uae.  Unlike 0.1 this will start right away.

Approaching Aster

It is really far too fast to actually play, just tapping enter after launching is enough to propel you into space in Frontier for example.  And  as you can see from the egg shape of Aster, older versions of UAE use a 1:1 pixel emulation which stretches, and distorts objects.  And it doesn’t correctly detect the screen margins.  I guess if it were 1996 it would be worth the time for something like SDL 2.0 where you can close the primary screen, and create another matching the needed resolution on the fly.

For anyone who cares to try my modified version of UAE-0.4 I’ve placed it on sourceforge.

If anyone has any old versions of UAE kicking around, especially any of the 0.5 releases I’d love to know.  Every old version I’ve found is here.