IBM System/23 Datamaster: Difference between revisions
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Video memory seems to be placed at address 8000h (to be confirmed).
=== Diagnostics ===
The System/23 Datamaster implements a set of self-test routines identified as "PID-1200". With them it tests the CPU, the memory and the different peripherals of the computer. Usually the results of the tests are written to the screen at start-up but if an error occurs before the initialization of the screen a probe is needed. The tests are identified by an hexadecimal value and can be presented unstyled, underlined or inverted. In the case of being underlined it means that the feature tested wasn't found by the system, whereas if it is inverted it has been detected but was tested and found faulty. If the text is left unstyled, it means the test passed. According to the Diagnostics user guide, the test routines and their tested areas are the following:
{| class="wikitable"
! Test !! Description !! Notes
|-
| 01 || CPU and data bus ||
|-
| 02 || First unpaged ROS ROM || This is the ROM at 0000h
|-
| 03 || Reserved || Unknown
|-
| 04 || RAM || Test for the first 64KB
|-
| 05-07 || CRTC || Initialization and test; any error in this step or earlier requires a probe
|-
| 08 || Page registers || For CPU access, ROM only
|-
| 09 || Unpaged ROS ROM || The second part of the unpaged segment
|-
| 10-19 || Paged ROS ROMs in the motherboard ||
|-
| 1A-29 || ROS Extensions || Test for ROMs in expansion slots
|-
| 2A-30 || RAM || Test for the last 64KB
|-
| 31 || Paging Register || For CPU access RAM only
|-
| 32 || Paging register || For DMA access
|-
| 33 || PIC || Interrupt controller initialization and test
|-
| 34 || PIT || Interval timer initialization and test
|-
| 35 || Keyboard || Tests if communication with the keyboard controller is successful
|-
| 36 || Printer || Checks if there is a printer attached to the computer
|-
| 37 || Printer diagnose || Sends a diagnose command to the printer and waits the response
|-
| 38 || Floppy disk drive controller || Checks if there is a FDC card in the expansion slots and if it is functional
|-
| 39 || +24V || Tests internal line of +24V supplied to the drives
|-
| 3A || Secondary printer || Checks if there is a printer control card in the expansion slot and checks if there is a printer attached to it
|-
| 3B || Secondary printer diagnose || If the previous test is successful, Sends a diagnose command to the secondary printer and waits the response
|-
| 3C || Internal wrap of serial interface adapter || Unknown
|-
| 3D || Disk unit || Checks if there is a 5247 external disk unit connected
|-
| 3E || Disk unit ready || In the previous test is successful, wait until the drive is ready
|-
| 3F || System diskette installation || Unknown
|}
Note that in case a ROM is unselected or unpowered it will mark its test as "missing". ROMs 0E and 0F aren't present on the board and therefore its tests will always result with a "missing" status.
== Gallery ==
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