IBM System/23 Datamaster: Difference between revisions

 

=== 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.

 

 

=== RAM Memory ===

[[File:System-23 64KB memory board.jpg|thumb|left|alt=System/23 64KB memory board|System/23 64KB memory board]]

RAM in the Datamaster is completely contained in one to two boards complementary to the motherboard and are attached through a card-edge connector of 36 pins each. This facilitates the removal and placement of memory cards into the system and grants the possibility of fast repair and extension of the computer. There are two memory slots, and at the same time official memory boards were produced in two sizes: 32KB and 64KB respectively. This led to five possible official configurations.

 

 

=== Diagnostics port ===

The System/23 has a dedicated diagnostics port. It is controlled by a single 8255 by using its port B, whereas ports A and C have no relation in function; for this reason it is deduced that port B is working in mode 0, without handshaking of any sort. This fact is confirmed by the eight data lines which conform the data port being directly connected only to port B and the remaining four signals are for supplying power to the probes.

 

 

For most cases it is not necessary having the probe, as the same values that are outputted through the service port are also written in the video memory, displaying the passed tests and the errors encountered. However, as the same tests that check the video display controller are the same routines that initialize it, all the tests made before the initialization cannot be seen in the screen until passed. In case some of them failed the screen would not be initialized and therefore the results wouln't be seen. For this reason the probe is still needed.

 

== Units in collection ==