Atari STE resuscitation

Atari 520STE

I thought that because of the Atari Falcon, I wouldn't need the Atari STE so much. After all, Falcon can be connected to a VGA and it has more processor power and features. Yet, this split focus resulted in not using either of them much.

Recently I got hold of an ACSI2STM, a tiny board that goes into the hard drive port of the Atari ST and the SD card contents show up as a number of hard drives. It cannot even be used with the Falcon as it doesn't have a similar port.

ACSI2STM

ACSI2STM is mainly what this blog post was supposed to be about. But it turned out the Atari STE needed some care. Before attaching the new drive, I wanted to see if the computer works at all. This led to various tiny fixes and upgrades.

I don't treat the STE as a museum piece, the case and various metal parts inside are already damaged, screws are lost and so on. But I'd like it to work and preferably without too much hassle.

RAM/ROM and boot-up

The STE already had 4MB SIMMs on board, but one of them was giving grief so I had to downgrade to 2MB, removing two of them.

For a 2MB configuration, the first and third socket from back to front, needs to be occupied with 1MB SIMMs (30pin, 70ns ideally).

Not the cleanest sight. 2MB of SIMMs in correct position. Case damage at top left.

I first thought the computer was more thoroughly knackered: 4 bombs appeared no matter what happened during the memory test. But it turns out the boot doesn't continue after the test if there is no boot drive.

The image below shows what can happen in a memory test: The test is nominally passed, but the screen memory was garbled at one time so the Atari logo and the test bar are no longer fully visible. The four bombs have also arrived, but this isn't really because of the test itself.

Memory test complete, failed completely.

This was confusing until I connected a Lotharek HxC floppy emulator as a dummy drive, which helped the computer go past that stage. If the ACSI2STM is online, a floppy drive is no longer needed. But it was good to learn this.

I could configure the HxC to run a disk image properly, but I ignored it for now. If it can help achieve a faster boot time, I could look into it.

How a happy memory test looks like, 2MB

I have previously upgraded to TOS 2.06 ROM, which goes against that idea of compatibility I mentioned above. Even software that looks like it plays nice with the OS, might be broken with 2.06.

But I like that I can finally select all files, or switch between text/icons view using keyboard shortcuts. Files can be viewed using a mask, and other small additions are in place. The memory check, although not infallible, is also included. The glitches with loading the DESKTOP.INF are gone and I don't need any kind of STE_FIX.PRG inside the AUTO folder.

Working 4MB of SIMMs

2MB is quite enough. Even if HD-modified and patched games and software are rather needy compared to the original requirements, none don't seem to require 4MB. Still, I ordered 4 x 1MB SIMMs to complete the picture.

Display

I've connected the STE to a Commodore 1084S monitor. The composite video cable picture is ok-ish for many low resolution games, but quite atrocious for the 640x200 mode, and the tiniest system font is almost unreadable even as black-on-white.

ST-to-1084S monitor 6-pin DIN plug is not a common thing. Scart cables are numerous so I ordered one of them instead and a Female Scart-to-DIN6 to complete it, because this 1084 doesn't have a Scart in.

Then it turned out it doesn't quite work that way. It was ok for an MSX2 Scart RGB cable I have made, but the Atari ST Scart cable I received wouldn't work this way.

Working!

So I ended up soldering my own cable after all, using the DIN13 part from the composite cable and a Six-pin DIN for the RGB end. It's a minimal version, with Atari STE the audio can be left out, but soldering the DIN13 is still annoying.

I struggled multiple times with supposedly fool-proof diagrams, yet still mirroring and mis-matching cables. So I do not even dare to supply my own diagram, as I could end up messing it up anyway.

I left out the 120Ohm resistors, as the brightness and contrast can be adjusted on a 1084. The resulting image is very crisp on the 1084S.

A VGA-cable for mono mode is a possibility, but I don't currently have a display that could do the required 70Hz. For displaying colour in VGA, the requirements are even more stringent, 15KHz horizontal and 50/60 horizontal.

Mouse and keyboard

I have a couple of working Amiga/ST compatible mice and and original Atari mouse in a bad condition. The two non-Atari mice didn't give problems, and I was actually surprised how smooth the Wizard mouse is.

Quite good mouse, but I couldn't get it to open.

I can also use the Micromys adapter I have lying around (C64/Amiga/Atari ST), but it looks like I've misplaced my best PS/2 mouse. Fortunately I have a couple of USB Logitechs (M-BJ58) that work with a further PS/2 adapter, but the wheel will be useless.

The mouse and the additional adapters dangle uncomfortably from under the computer, and I felt the 2nd mousebutton failed occasionally, and some times even the entire Micromys went offline.

Then I remembered the ST ports can become loose, and sure enough the port was wiggly.

The underside of the keyboard circuit board

The keyboard comes off easily enough. I've sometimes thought of modding it into a separate keyboard, but the mouse and joystick port position makes this less practical. Besides I believe it's better off integrated anyway, less loose parts the better for storage.

For the purposes of inspecting and fixing the ports, the arrangement is really annoying. I have to open the whole keyboard case, and only after that the mouse port can be resoldered. There are like 30 tiny screws to remove and to be put back together again.

And the topside

While at it, I removed any dust that might affect the key bubbles, and as I had to take them loose anyway (they drop off) their positions are swapped and I also got to wipe the entire board.

As a result the numpad 2 key, which was slightly unresponsive, now works better.

Zooming into the broken solders

The above picture shows the damaged solder in the mouse port, compared to the game port which is intact. I ought to have taken a more precise picture, but the cracks are already visible here.

If I read this correctly, it is indeed the right mouse button pin which is most loose, and losing the 5V/GND might easily disturb the Micromys adapter.

I did consider wiring the mouse port entirely to the back of the case, but after drilling in a DB9 to the corner I chose not to do this now, because it's better to plan it more. I may come back to this.

After the resoldering the mouse worked fine. I'll use the 9-pin Wizard mouse at least until problems arise.

Keep those rubber bubbles carefully in place when reassembling

For a while, I had swapped the keyboards between the Falcon and the STE. Not sure why, I suppose the STE keyboard worked better and I wanted to benefit from that when the Falcon was timely. Neither have Scandinavian keys. I put the keyboards back into their correct homes.

Power Supply Unit

One more thing, a PSU replacement. I have no reason to think the old PSU is giving up, but I felt better doing this as a clean-looking replacement was available and they might disappear eventually.

The Atari ST PSU replacement from 16-32bit.eu

This should produce less heat than the old one. I was also persuaded by the included USB port, which can power the ACSI2STM – yes it needs that current to work. I guess the 5V could have been taken from the board, but this is a straightforward solution.

The old PSU

The PSU replacement needed some soldering, but nothing too difficult.

Four screws are removed, the connector to the motherboard (with the 5V/12V/GND wires) is removed, then the board can be pulled up and the two mains leads can be soldered off. I didn't even use a pump, just gently pulled the wires out one by one while heating the other side.

PSU removed

After the whole board is loose, the motherboard connector wires are soldered off. All cables are soldered back to the new board, one by one starting again from the 5V/12V/GND wires. 

Obviously refer to the instructions from the seller.

Replaced!

The result looks cleaner, whatever magic may be inside those boxes.

So, off to the world of Single Tasking.

Atari ST

I had an Atari STE in the beginning of the 1990s and alongside with the Amiga it was my entry point to 16-bit computers.

The Atari ST and Atari STE

Powered with a Motorola 68000 chip, typically equipped with 512 or 1024 Kilobytes of memory and a 3.5 inch floppy disk drive. The display resolutions were 320x200 with 16 colours or 640x200 with 4 colours. Initially, these colours were selected from a total of 512, whereas the later STE extended this to 4096, as in an Amiga. With a special monochrome monitor you could have 640x400 black and white display. Sound came by courtesy of the Yamaha YM2149 chip or DMA sample playback on the Atari STE, which also brought in hardware scrolling.

More advanced models such as Mega ST, Atari TT and Atari Falcon would have better specs, but I'm only really talking about the ST/E.

You could plug a mouse and a joystick into it and play games or run programs. With the MIDI ports built-in, it became a cheap alternative for amateur and professional musicians alike.

A semi-naked Atari STE, with the disk drive removed.

The Atari ST desktop

The graphical desktop with the green background is called the GEM. The operating system is called TOS (Apparently, The Operating System). Both are included in the Read-Only-Memory, which is a bit unconventional but handy for a floppy-disk based user.

I have mixed feelings about the GEM in its simplest forms. Funnily enough, it kind of resembles what we now have in touch screens: simple graphical means for launching apps, and not much else. In huge hindsight, the ST might have benefited from having a BASIC in the ROM, 8-bit style, instead of this wonky desktop that cramped creativity.

Positively, as the GEM was stuck into the ROM it was really quite universal for Atari ST. With this in mind it was good that the GEM could be customized with software such as RAM disks, command shells, alternative file selectors, virtual hi-resolution etc. With some luck these could be integrated together with all properly written GEM software, adding more sophistication to the system than there seems to be.

Which isn't much, to be honest.

There were also full desktop alternatives such as KAOSdesk. For a graphic journey through the TOS versions and alternate desks go here.

Typically, a poor Atari user would have 3.5 inch floppy disks with 720Kb capacity. The Atari ST uses DOS-style filenames, with 8 letters and a 3-letter extension. So, TXT and DOC files can reasonably be expected to be text files. Rather generously, the GEM can display text-files and readmes without a separate program.

PRG, TOS and TTP (TOS-Takes-Parameters) files can be run as executables. The TTP file expects typed arguments which sometimes worked with ARC, LZH, LHA and ZIP archivers. (Or even ZOO... anyone remember ZOO?)

TOS/GEM upgrade

I just upgraded my STE ROM chips from 1.06 to 2.62, the final version for STE. The upgrade is not difficult but requires some soldering as the jumper settings have to be changed. This also limits somewhat the switching between ROMs. There are a lot of tiny improvements and the GEM feels generally slicker. Some incompatibility may arise, though.

The ROMs are under the floppy drive. The jumpers are on the right (here not set correctly)

WIth these earlier TOS versions, there is no multi-tasking, but there are some workarounds to this in the GEM environment. It can seem toy-ish compared to an Amiga Workbench, but if I had to pick between the two as purely floppy-based systems, I would prefer the Atari GEM.

Desk Accessories

Programs with the .ACC extension, when placed in the root directory of a floppy disk, will be run automatically upon booting and added to the list of resident "accessories".

These can be then called from the GEM top left menu. Control panel, calculators, tiny text editors, games and so on somewhat compensated for the lack of multitasking.

The AUTO folder

The auto folder was a neat way of auto-booting any file on disk without the need to edit any scripts. Create a folder named AUTO. Place an executable file inside it so your Atari ST will run it when booting. *.TTP and *.TOS filename extensions have to be changed to PRG.

If I remember correctly at least some TOS versions occasionally refuse to load the accessories, another glitch I think.

AUTOSTART.PRG

Sadly, the running order inside the AUTO folder depends mostly on which order the files were chucked there. A special software could be used for re-ordering them.

STE_FIX.PRG

One of the silly bugs in version TOS 1.06 in Atari STE messed with the resolution so that the medium resolution (the most useable for TOS) setting would not work when booting. Place the STE_FIX.PRG inside the AUTO folder mentioned above. Or get another version of TOS.

Command shell?

Sadly the GEM does not come with a command shell, more handy for many things. There are shells, though, and the GEM/TOS communicates quite well with them. The most extensive of them, the OKAMI shell, is a reasonable facsimile of a unix/linux type shell but this can be a bit too clever for its own good.

With OKAMI you can use ls, cd, more and so on for examining files and disk contents, but also more complex things like paths and shell scripts. OKAMI's slow and cumbersome for floppy drive use on a standard Atari ST, and it takes nearly 100K so it does not boot instantly.

Games

What's good? Highly subjective. I maybe spent most time playing Larn, Midwinter, Knights of the Sky, Railroad Tycoon, M1 Tank Platoon, Damocles and Llamatron. A lot of people swear by Dungeon Master and Oids. Oh, and the games mentioned here are not particularly Atari ST-specific, as they were available for the Amiga and PC, too.

Recently I've played Larn and been able to get into M1 Tank Platoon too, Virus and Stunt Car Racer are not bad but honestly I'd say most 16-bit games, especially with 3D-graphics, are not highly playable.

SD card readers

It would be wise to throw away the floppy drive and get a card reader instead. A HxC floppy emulator does a pretty good job, whereas an Ultrasatan device can be more flexible for replacing a hard drive. (In fact, loading floppy games poses some, but not insurmountable, problems for the Ultrasatan)

HxC is simplicity itself: remove the internal floppy drive and connect the Floppy Emulator with the drive cable and the floppy drive power cable.

The Atari outputs composite video, but there is no direct connector for it.

Amiga/Atari ST combo mouse was a common sight in the past and should not be hard to get.

Here's a good site for deciphering all the connectors of an Atari ST. It seems a VGA for monochrome is not that hard to build, but the weird monitor cable plug may not be easily available.