New Diagnostic Tool

J

JYewman

New Tinkerer
Aug 21, 2025
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Hi All,

I wanted to share with you a project that RetroSix is currently working on for diagnosing my Macintosh SE/30 using the serial diagnostic interface, which can be accessed via the modem port on most compact Macs (or anything compatible with the TechStep).

It's a really useful piece of software to automate command inputs and reading outputs. He is also considering creating a diagnostic tool that connects to the serial port and to your PC via USB-C if there is enough interest.

I'll keep this space updated with developments, but below is a look at the development so far!
 
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JDW

JDW

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Wow. Pretty amazing, although it does appear to be created for programmer types.

So, is this new software a more polished version of the TechStep protocol that Adrian shows in his video at 20:29?

 
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JYewman

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Aug 21, 2025
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JDW said:
Wow. Pretty amazing, although it does appear to be created for programmer types.

So, is this new software a more polished version of the TechStep protocol that Adrian shows in his video at 20:29?

Click to expand...
Yeah, so this is a GUI interface for the actual console. It saves you from having to manually type out commands, so it completely automates the TechStep protocol. It will eventually give you full diagnostic outputs without having to interpret the codes.
 
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JDW

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So basically it transforms an a modern computer into a TechStep substitute, which is groundbreaking because it would meaning it would be accessible to everything and not just the wealthy. Real TechStep devices are much to expensive and even the recreation isn't cheap. A software solution really is quite brilliant.

With that said, the TechStep does more than just attach to the serial ports. It connects to the headphone jack and ADB and SCSI too (at least on the SE/30), so I'm interested in hearing what it can and cannot do versus an actual TechStep.
 
J

JYewman

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Aug 21, 2025
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JDW said:
So basically it transforms an a modern computer into a TechStep substitute, which is groundbreaking because it would meaning it would be accessible to everything and not just the wealthy. Real TechStep devices are much to expensive and even the recreation isn't cheap. A software solution really is quite brilliant.

With that said, the TechStep does more than just attach to the serial ports. It connects to the headphone jack and ADB and SCSI too (at least on the SE/30), so I'm interested in hearing what it can and cannot do versus an actual TechStep.
Click to expand...
It definitely could! I have just spoken to Luke about it! I'll have more info soon!
 
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wottle

wottle

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This is a really cool idea. Is the TechStep just a device that is sending and interpreting commands over the serial connection? It would be really cool to pair this with a usb-c to serial cable (plus mini DIN 8 adapter) with an iOS app that does all the things the TechStep does.

It appears Apple doesn't allow App Store Apps to use the serial cable directly, and a company has a solution that uses their proprietary cables, but you need to use their SDK (https://redpark.com/developer-tools/) and that would prevent you from distributing in the official App Store. Another cool idea would be to create a custom Raspberry Pi install that works as the server, which is doing all the communication to the device via a USB serial adapter. The Pi could offer a web interface to do most things, and APIs to allow you to have an iOS app to replicate the interface of the TechStep. Would be a really cool tool for the community.
 
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joevt

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How does the TechStep serial stuff relate/differ to the Serial Test Manager stuff in Power Macs? The Serial Test Manager can't do headphone jack and ADB and SCSI tests like the TechStep can. In Power Macs, the Serial Test Manager has a menu that lists the supported commands.
https://68kmla.org/bb/index.php?threads/the-820-0961-a-mystery-g3-3-3v-flashrom.48746/post-548608

Serial Test Manager is found in the versions of Open Firmware listed below in the HWInit or ExceptionTable (Start) sections. Serial Test Manager may exist in all 32-bit Power Mac ROM versions but I do not have all of them to verify.

In HWIinit:
0.992j
1.0.5
1.0.5a
1.0.5b
1.0.5PipPCI
1.0.5PipPCI2
1.1.22
2.0
2.0.2
2.0.3

in ExceptionTable (Start):
2.0.1
2.0a9
2.0f1
2.3
2.4

in Part 00 of Recovery and Rom Image = HWInit:
3.1.0f1
3.1.1f4
3.1.2f2
3.1.3f2
3.1.3f3
3.2.4f1
3.3.2f1
4.1.0f1
4.1.7f4
4.1.8f5
4.1.9f1
4.2.5f1
4.2.7f1
4.2.8f1
4.3.2f1
4.4.0f1
4.4.1f1
4.4.5f3
4.4.8f2
4.5.4f1
4.5.7f1
4.5.8f1
4.6.0f1
4.6.2f1
4.6.4f1
4.7.1f1
4.8.5f0
4.8.7f1
4.8.9f4
4.9.3f0
4.9.4f1
4.9.5f3
4.9.6f0

64-bit Power Macs do not have the Serial Test Manager or it has taken a different form.
 
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