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  • Atari 520STM Restoration Pictures I thought I'd post pictures of my latest restoration project as I realized I had never done that . Unlike my previous projects, this was a "restored to order" job with some specific requests.This was the starting point. A little dirty but not bad at all.Here is the motherboard before any work has been done. Very clean. It's the last revision of the small STs and only one that supports 2-chip TOS.Right off the bat I noticed that there has been minor rework on the board. It's clear that a bunch of resistors have been changed. They are connected to the RAM chips and the MMU (memory management unit). It seems that someone wanted ...
    Posted Jul 4, 2018, 2:57 AM by Joshua Kaijankoski
  • Mega ST Keyboard Switches They are mechanical and they are Cherry MX Blacks. I know because I finally took one out. No membranes anywhere. This is not a new discovery but something I had to verify myself because of lack of evidence.Some people complain that Mega ST keyboards aren't as good as TT/MSTE membrane keyboards that have tactile feedback. And they would not be wrong if that's what they are after.Mega ST's Cherry MX blacks are linear switches, meaning they have no click or tactile feedback by design. They are also one of the earliest Cherry switches from 1984.The beauty of the Cherry MX switches, and therefore the Mega ST keyboards, is that they are replaceable. If ...
    Posted Jul 3, 2018, 1:31 AM by Joshua Kaijankoski
  • Atari TT030 REV.C Rework Guide This started out as a guide for myself to do the rework down the road. This is for REV.C (PGA CPU) which is the model after the daughterboard REV.A and one before the REV.D-K ("SMT Models"). Took a long time to do. I hope someone finds it useful. Filesize is big, but for a reason.
    Posted Jun 10, 2018, 1:43 PM by Joshua Kaijankoski
  • Atari TT030 REV.D Rework Guide Here is the REV.D and up rework guide. Note that some REV.H have the RTC fix built-in and certainly later models. REV.J and REV.K typically have the VME Bus Fix and perhaps others.
    Posted Jun 15, 2018, 12:13 PM by Joshua Kaijankoski
  • ST World: Atari STacy Review
    Posted Apr 26, 2018, 7:04 AM by Joshua Kaijankoski
  • Getting Back to Business (Bit by Bit) So, it's almost the end of April. Crazy. Things have been great at my new job. I've learned a lot. I've already programmed several tools with GUIs with my new best friend; PowerShell. It's amazing.I feel like I'm at a place where I can focus a bit of my time to running Atarian Computing again although, I will be busy renovating my place of operations (roof and exterior). You should be hearing more of me in the coming weeks.
    Posted Apr 24, 2018, 3:33 AM by Joshua Kaijankoski
  • Situation Report I apologize for no updates in the recent months. I'm still fully committed to running this website. Due to major changes in my full-time employment, all my free time has been diverted to learning the ropes and teaching myself new skills. The changes are very positive and my employer has remained the same. I now work in IT for a major insurance company where I can fully utilize my skillset. With the holiday season coming up as well, I expect that it will be a couple of months before I can start working on my Atari projects. Merry Christmas and a Happy New Year to all.Josh.
    Posted Dec 19, 2017, 11:04 PM by Joshua Kaijankoski
  • Atari STacy TOS 2.06 Upgrade IntroductionWhen the Atari STacy came out in 1989, the latest TOS version at the time was TOS 1.4. During the lifetime of the STacy, Atari only shipped units with TOS 1.4 installed. STacy never got to enjoy the success of her big brothers and as a result there were hardly any upgrades made for her. Many who wanted to upgrade the STacy's TOS were told by experts that because of the LCD and Shadow chip, the STacy needed a special version of TOS to run. Since Atari only ever shipped with TOS 1.4, the assumption was that TOS 2.06 would not work. At least not without modifications. Many Atarians, however, managed to hack and ...
    Posted Oct 8, 2017, 2:34 AM by Joshua Kaijankoski
  • Programmers' Forum - #21 Programmers' Forum was a regular monthly column in the ST Applications magazine, starting with Issue 2. This edition of Programmers' Forum is available as an OCR'd PDF here.
    Posted Sep 10, 2017, 11:08 PM by Joshua Kaijankoski
  • Programmers' Forum - #20 Programmers' Forum was a regular monthly column in the ST Applications magazine, starting with Issue 2. This edition of Programmers' Forum is available as an OCR'd PDF here.
    Posted Sep 10, 2017, 11:05 PM by Joshua Kaijankoski
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Atari 520STM Restoration Pictures

posted Jul 4, 2018, 2:55 AM by Joshua Kaijankoski   [ updated Jul 4, 2018, 2:57 AM ]

I thought I'd post pictures of my latest restoration project as I realized I had never done that . Unlike my previous projects, this was a "restored to order" job with some specific requests.

This was the starting point. A little dirty but not bad at all.

Here is the motherboard before any work has been done. Very clean. It's the last revision of the small STs and only one that supports 2-chip TOS.

Right off the bat I noticed that there has been minor rework on the board. It's clear that a bunch of resistors have been changed. They are connected to the RAM chips and the MMU (memory management unit). It seems that someone wanted 68ohm resistors instead of the original 33ohms. Marked in yellow. No idea why it was done and no reason to. I decided to revert to 33ohms.

The first specific request was for 1MB ram instead of the 512KB from factory. I chose to upgrade using the same method Atari used on the 520+, which was the piggyback method. I took some old 256KB simms with suitable 41256 chips and removed 16 chips that I then proceeded to solder on top of the 16 ram chips on the motherboard leaving pins 4 and 15 free to run wires. For more details see this thread on atari-forum.com.

I left wires long at this point. This board revision had nice locations for the wires. I installed 68ohm resistors and cut the bridge on the other side on RAS1.

Here I reverted back to the original 33ohm resistors. Notice the fruit of my OCD with the stripe alignments. This was worth doing just because this previous change was a botch job. The original resistors had been snipped off instead of properly desoldered and crazy amounts of solder was used. It was really crusty.

Here's a post op picture of the solder side of the same location. The solder mask was quite fragile so I applied solder mask where needed and cured it with UV.

Here's a shot of a cleaned top case. I always remove the badge as it's very susceptible to damage. I also always spray a few coats of matte lacquer on it to give it some protection.

The second specific request was for a dual TOS. There was to be no visible switch either. I had to hack a solution as I had a deadline to keep. Here is the result. I used two 27C020 chips. I'm picking VCC of the neighboring sockets because A17 (pin 30) is obscuring VCC on pin 28 of socket. Likewise it's easier to pick A16 from pin 22 of neighboring socket rather than routing it awkwardly under the chip. Then GND is connected to OE. A17 is pulled low by 10K resistor when jumper is off. That's one TOS version. Putting in the jumper pulls A17 to +5v and another TOS is selected. Not pretty but it works. I made a point of not soldering anything on the board in case the roms got changed.


Here we have all board work complete. I changed all the caps and pull-up resistors for the address lines to 3.3Kohms. All circled below.
 
Underside completed. Reflowed most of the connection. Applied soldermask where needed and then a thorough cleanup.

Like new. Keycaps are double-shot so very durable and you can't erase the legends. Note the different shade loose key. I've encountered at least three different shades of keycaps. 
Finished product. Picture doesn't do it justice.

For all this, the customer paid $140 + shipping.

Mega ST Keyboard Switches

posted Jul 3, 2018, 1:31 AM by Joshua Kaijankoski   [ updated Jul 3, 2018, 1:31 AM ]

They are mechanical and they are Cherry MX Blacks. I know because I finally took one out. No membranes anywhere. This is not a new discovery but something I had to verify myself because of lack of evidence.

Some people complain that Mega ST keyboards aren't as good as TT/MSTE membrane keyboards that have tactile feedback. And they would not be wrong if that's what they are after.

Mega ST's Cherry MX blacks are linear switches, meaning they have no click or tactile feedback by design. They are also one of the earliest Cherry switches from 1984.

The beauty of the Cherry MX switches, and therefore the Mega ST keyboards, is that they are replaceable. If I want click and tactile feedback, I can just replace the switches with Cherry MX Blues from 2007. Not the easiest task because each switch is soldered on the PCB with two pins and attached on a thick metal plate. This is why Mega ST keyboards are so heavy.

So I might just do that, replace all switches with MX Blues. Here are some pictures of the switch I removed. Phone had a hard time focusing.


Atari TT030 REV.C Rework Guide

posted Jun 10, 2018, 1:43 PM by Joshua Kaijankoski

This started out as a guide for myself to do the rework down the road. This is for REV.C (PGA CPU) which is the model after the daughterboard REV.A and one before the REV.D-K ("SMT Models"). Took a long time to do. I hope someone finds it useful. Filesize is big, but for a reason.

Atari TT030 REV.D Rework Guide

posted Jun 10, 2018, 1:43 PM by Joshua Kaijankoski   [ updated Jun 15, 2018, 12:13 PM ]

Here is the REV.D and up rework guide. Note that some REV.H have the RTC fix built-in and certainly later models. REV.J and REV.K typically have the VME Bus Fix and perhaps others.

ST World: Atari STacy Review

posted Apr 26, 2018, 7:04 AM by Joshua Kaijankoski


Getting Back to Business (Bit by Bit)

posted Apr 24, 2018, 3:33 AM by Joshua Kaijankoski

So, it's almost the end of April. Crazy. Things have been great at my new job. I've learned a lot. I've already programmed several tools with GUIs with my new best friend; PowerShell. It's amazing.

I feel like I'm at a place where I can focus a bit of my time to running Atarian Computing again although, I will be busy renovating my place of operations (roof and exterior). You should be hearing more of me in the coming weeks.

Situation Report

posted Dec 19, 2017, 11:04 PM by Joshua Kaijankoski

I apologize for no updates in the recent months. I'm still fully committed to running this website. Due to major changes in my full-time employment, all my free time has been diverted to learning the ropes and teaching myself new skills. The changes are very positive and my employer has remained the same. I now work in IT for a major insurance company where I can fully utilize my skillset. 

With the holiday season coming up as well, I expect that it will be a couple of months before I can start working on my Atari projects. Merry Christmas and a Happy New Year to all.

Josh.

Atari STacy TOS 2.06 Upgrade

posted Oct 8, 2017, 1:41 AM by Joshua Kaijankoski   [ updated Oct 8, 2017, 2:34 AM ]

Introduction

When the Atari STacy came out in 1989, the latest TOS version at the time was TOS 1.4. During the lifetime of the STacy, Atari only shipped units with TOS 1.4 installed. STacy never got to enjoy the success of her big brothers and as a result there were hardly any upgrades made for her. Many who wanted to upgrade the STacy's TOS were told by experts that because of the LCD and Shadow chip, the STacy needed a special version of TOS to run. Since Atari only ever shipped with TOS 1.4, the assumption was that TOS 2.06 would not work. At least not without modifications. Many Atarians, however, managed to hack and install some major upgrades. Most notable of these is Darklord's PAK. It required major mods to even have it fit inside the STacy. His PAK had a modified TOS 3.06 custom made by Holger. Even though Darklord's STacy runs happily with TOS 3.06, it was not certain whether or not the modifications made by Holger were in some way STacy specific. I wanted to take a really close look into the upgradeability of the STacy and if there was anything I could do to make it easier.

The STacy Expansion

Every STacy has a space and spot for an expansion bus on the left side of the motherboard. On very few units, it's actually populated by a connector facing outside behind a cover. Whatever expansions Atari had initially had in mind were meant to be external. Apparently Atari didn't think it was a good idea and scrapped the whole idea of an expansion connector. All STacy units since then had the holes and silkscreen on the PCB. On the STacy I'm typing this piece on, and the recipient of the upgrades, has a cover on the bottom case. My other STacy does not have a cover.
This connector is essentially the same as the Mega ST's Mega Bus. Any expansion for the Mega ST should work on the STacy. Provided there is a way to connect it to the STacy Bus and find a way to fit it inside the case.
What I want to do is make an adapter for the STacy Bus. It's called the STaceX (pronounced similarly as SpaceX) and it is progressing quite well. This article is about the TOS 2.06 upgrade, however, so I won't go into too much detail about the STacy. The reason I wanted to bring up the STacy expansion is that all signals in the TOS 2.06 upgrade can be plugged into the bus instead of soldering on the CPU.

The TOS 2.06 Upgrade

One of my Mega STs had a TOS 2.06 upgrade on it and I got the idea to install it on this STacy utilizing the expansion bus.
The upgrade is the one pictured above. This is not my picture but part of a thread in Atari-Forum.com The installation manual can be found here. The ribbon cable is divided into two parts; 22 signals that go into the CPU/BUS and the rest into a 28pin adapter that plugs into one ROM socket. No traces need to be cut, and if you use the BUS version, no soldering is required either.

STacy's ROM Sockets

Like the STE, STacy has two 32pin ROM sockets. Unlike the STE, however, they are not entirely pin compatible with the 27C010. There are also no jumpers/resistors to switch between different ROM types. It would also seem that the STacy has no way of decoding TOS 2.06 like the STE.
STacy's ROM sockets are for the Toshiba TC571001. Compared to 27C010, pins 2 (A16) and 24 (/OE) are switched. But, as a result, the TC571001 is compatible with 28 pin 1Mbit Mask ROMs. This can also be verified from STacy's schematics. It has an outline for 32 and 28 pin ROMs.
This non-standard pinout only served to fuel the speculation that the STacy needed a special version of TOS in order to drive the LCD and Shadow chip.

Installing the Upgrade

The more I thought about it, the more I was convinced that the upgrade was possible. I also thought it would be a very good reason to test the idea of STaceX and prep the motherboard for it. The first step was to populate the STacy expansion port. There was some tape covering the holes on both sides of the board. This turned out to be an extremely frustrating thing to removed. The tape had fibres on it and almost 30 years had caused it to get stuck pretty good. I used copious amounts of ŠIPA and a toothbrush to help remove it. It took time but I was able to remove it all. It was super sticky and clogged the holes as well. I used three 24pin male headers that I had tied together to maintain proper alignment. They were a breeze to solder on the motherboard.
Using an early STaceX prototype PCB picture, I mapped the pins needed for the TOS upgrade. I used female header connectors on the ribbon cable.
First I plugged the adapter to the HI ROM socket. Turns out that this fit perfectly on the STacy's SUB PCB, where the ROMs, RAM and KBD are located. The ribbon cable went right next to the SUB PCB connector towards the STacy motherboard.
I then plugged the 22 plugs into their corresponding pins on the BUS header. I laid out the entire ribbon cable so that it fit perfectly right under the DC/DC board. The upgrade PCB with the ROMs peeked out from the backside of the STacy. For the STacy cover to be able to close, I needed to remove the battery compartment's bottom. After that it was perfect.

Success!

It booted right up. It was a very satisfying moment. After playing with it for a few minutes I was convinced that everything worked normally. All STacy specific CPXs worked. The LCD was able to go to sleep normally so definitely not a TOS Šfeature.
There have been no problems whatsoever and this entire piece is written on the STacy with the TOS 2.06 upgrade using Protext 6.511. If anyone has Protext 6.5 or 6.6 to sell with manual, please contact me. I must say, the STacy's keyboard is by far superior to my TT or Mega ST keyboards. This project has motivated to work on the STaceX with more confidence. I have a few projects in the works. I will inform more on them later.

Programmers' Forum - #21

posted Sep 10, 2017, 11:08 PM by Joshua Kaijankoski

Programmers' Forum was a regular monthly column in the ST Applications magazine, starting with Issue 2. This edition of Programmers' Forum is available as an OCR'd PDF here.


Programmers' Forum - #20

posted Sep 10, 2017, 11:05 PM by Joshua Kaijankoski

Programmers' Forum was a regular monthly column in the ST Applications magazine, starting with Issue 2. This edition of Programmers' Forum is available as an OCR'd PDF here.


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