IBM System/23 Datamaster: Difference between revisions
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== Hardware Description ==
=== Microprocessor ===
The CPU selected to serve as the core of the system was the Intel 8085. However, as the component references were ofuscated identifying the CPU was not a straightforward task. It was hinted that the component with reference 4178015 could be the part. To confirm the true identity of the integrated circuit, an exchange with a legit 8085 was done: the remarked part went into a P2 CPU board and the P2 CPU went in place of the unknown component. The test went successfully and the cross reference was proved as fact.
[[File:IBM 8085 CPU being tested in the Alphatronic P2.jpg|thumb|left|alt=IBM 8085 CPU being tested in the Alphatronic P2|IBM 8085 CPU being tested in the Alphatronic P2]]
As a side note, when studying part of the code, it was discovered that the ROS makes intensive use of the undocumented opcodes of the 8085. This was in part to hinder efforts to reverse-engineer the computer and its firmware and bring compatibility with the System/34 BASIC by emulating some of its registers.
=== ROM Operating System ===
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! ROS Code !! ROM Reference
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The memory boards contain one or two TMS4132 arrays of 9 memories each. Having nine units per bank allows them to have a data byte width of data plus a ninth bit for parity. Both because of the rareness of the format of the TMS4132 and the replacement of the official reference led for years to believe that IBM soldered the memories in piggyback to cope with failure rates when in reality it was a feat of Texas instruments to sell them directly soldered after manufacture of both dies. This kind of memory contains a 16KB bank per package and both packages have a slight difference of the pinout to not have conflict with /CAS and /RAS.
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|+ Official RAM configurations
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== Units in collection ==
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! Inventory ID !! Model !! Submodel !! Comments
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