MiNT is an operating system extension that adds unix like features to
TOS. MiNT started at the end of 80's as Eric Smith's (who ported also
most of GCC and NetHack to Ataris) university project. Later Eric Smith
was employed by Atari Corporation and 1994 MiNT v1.04 became official
part of the Atari computer packages. MiNT still remains GNU copyleft
and therefore is available freely.
MiNT adds / offers the following services to TOS:
- pre-emptive multitasking
- memory protection for processors with MMU
- virtual root file system with /proc, /dev, /pipe, /shm
- named pipes (/pipe/) and shared memory (/shm/)
- signals and simple messages
- threads (ATM stack fixed to 4KB)
- shared binaries
- loadable file-systems
- loadable devices
Things to beware in the kernel (TOS compatibility):
With GCC and MiNTlib (Atari/MiNT ports of the FSF GNU ANSI-C compiler
and library) most of the unix sources compile quite painlessly. MiNTlib
implements functionality both from BSD and SysV along with Posix. Not
quite as well as Linux (MiNT has much less users to fix that), but mostly
well enough. Much of the work in GNU/MiNTlib has been done by Jhawar
Bammi and Howard Chu. MiNTlib has been ported also to Lattice, Pure,
68k and SozobonX C compilers (of which first two are commercial). For
source-level debugging GCC compiled programs there's Gdb.
- Processes are allocated a fixed amount of stack, not
`unlimited' like on unix. Programs have a `_stksize' variable
in their headers which can be manipulated with an appropriate
- MiNT uses TOS I/O routines, which aren't designed for
multitasking. Especially reads and writes from/to disk slow
other processes noticeably. There's a hack in MiNT kernel
which lowers priority for programs which are polling but
not receiving. Properly written
(=MiNT/unix) programs of course use select().
- On 68000 processors, which don't have a (proper) MMU,
neither virtual memory nor memory protection can be used.
Current MiNT implementation also suspends multitasking while
processor is in the supervisor mode so that above mentioned
I/O routines will work correctly.
- Any program can enter supervisor mode and bypass kernel
memory protection (which is mainly intended as an aid for
programmers) therefore MiNT is not secure multiuser
environment. For that I'd recommend either a BBS system or
some non-TOS based operating system. If this behavior
would be changed, it would break almost all existing code,
even ones compiled with MiNTlibs (it uses 'cookiejar' for
getting system information).
- A preliminary virtual memory support is added to MiNT v1.14.
It can be used with 68030 but isn't yet very stable. One of
the reasons is (besides some bugs) is that there's no
protocol to tell which code (like new interrupt routines
(remember, this is just a unix 'emulator'!)) cannot be
Things to beware with programming:
- MiNT library isn't thread-safe because when
GNUlib was ported it was that neither. And because threads
have currently fixed 4k stack (defined in the kernel
sources) their usage is somewhat limited. You should also
note that GEM is not re-entrant. In conclusion,
you should thread only code that does all by itself...
- Correctly working GCC versions for Atari are: v2.3.3,
v2.4.5, v2.5.8, v2.6.3, v2.7.2. Others may produce code that
doesn't work, especially versions before 2.6.
- GCC needs huge amount of of memory. You should have at
least 4MB of memory (even the cc1 binary is on latter
versions well over 1MB in size) if you're compiling larger
programs (function code size affects more than overall code
size). With C++ code you will need quite a bit more memory.
MiNT extensions and utilities
Kay Römer has programmed MiNTNet: MiNT socket device, TCP/IP
networking OS routines and programming library, C/SLIP and PPP protocol
drivers. He has also ported the basic unix networking utilities and
others have ported applications.
Minix2-filesystem is essential for a programmer porting unix software.
It implements long filenames (length selectable), soft and hard links,
user/group/global permissions and more efficient disk usage than that of
the native FAT filesystem.
Some other device / filesystem drivers are:
MiNT implements device interfaces for standard devices (console,
keyboard, mouse, parallel, serial and midi) itself. External
filesystems and devices are loaded at MiNT startup.
- dynamic ramdisk. Filenames are case insensitive and limited
to 30 characters. Only soft links are implemented.
- audio device, works on all Ataris, with or without DMA.
Unfortunately it's ioctl() calls are incompatible with Sun
/dev/audio or Linux /dev/dsp devices.
- CD-filesystem (ISO-whatever).
- raw floppy device.
With MiNT + MiNTNet + minix-fs you can also run a monochrome X11R5
server. Some of the basic X software has been ported like fwvm and
chimera. You need at least 4MB of ram, but 8MB is required if you're
doing anything besides testing. There are no baserelative (for doing
shared binary code) versions of the X libraries.
Other multitasking friendly windowing systems available are an old
version of Bellcore MGR, W window system and
various still incomplete freeware AES (upper level GEM part)
replacements. Commercial N.AES is reported to be excellent MiNT
friendly AES replacement (much faster and more robust than MultiTOS).
If one wants to run a complete unix style multiuser environment on his
machine, he can install the KGMD (Knarf's German MiNT distribution)
package. It includes binaries for all the normal unix stuff (file and
text utils, manuals, inetd and servers, sendmail, GCC, Emacs, X etc.).
Note: As a multiuser system it's quite unsecure! See
MiNT and unix differences above...
Nowadays MiNT developers are almost non-existing. Most of the original
MiNT hackers have acquired either 68k-Linux (if they have an Atari with
68030), x86-Linux or Free/NetBSD. Sven Karlsson who contributed the
latest larger MiNT upgrade, virtual memory (result of testing it for
fenix), is concentrating on his new 680x0 micro-kernel, Fenix. It
My Atari page has several links for MiNT
(and Atari) binaries, source and information.
There's available a MiNT version that's modified for VME-bus 680x0
cards. I don't know anything more about that.
A port of MiNT was the first free `unix-emulator' on Apple Mac
computers. This was doable because they use the same Motorola 680x0
processor series as Ataris (and newer PowerMacs can emulate it). AFAIK
only MiNT scheduler and some other critical parts are done in assembler
code rest is C (just a wild guess, I haven't got MiNT sources anymore).
MacMiNT is implemented on a top of JET (Just Enough TOS) TOS emulator
which implements just those parts of TOS (680x0 traps I think) that MiNT
hooks into. Latest MacMiNT version is AFAIK 1.12 and there's also a
private port of MiNTNet that maps MiNTNet calls to respective Mac ones.
With MacMiNT one can run text-only Atari program binaries like GCC and
Emacs on a Mac.
Nowadays NetBSD is also ported to Macs (and Linux is on the works for
PowerPC based Macs), but it replaces the System completely whereas
MacMiNT multitasks it's programs in a Finder window along with other Mac
My MiNT utilities
I myself couldn't have used my ST without these...