C128/C128D RAM EXPANDER TEST
VERSION 1.2.1
8726 REC (RAM EXPANSION CONTROLLER)
The REC is a DMA Device used to Transfer Blocks of Data between the C128
or C128D and the Expansion RAM.
* The Verify Option is tested by Testing Both Verify and Verify Error
Conditions with the Interrupts ON.
* This Detects the Majority of REC Failures
* If either test Fails, the REC is 'BAD'
* If both Verify Conditions are met the Test Continues
* The Swap Option is tested by Loading the Expansion RAM with a
Pre-Selected Random Pattern, Clearing the Host RAM, Swapping RAM
and Comparing the Two RAM Areas.
* If either RAM Area does not compare to the Pattern, the REC is 'BAD'
* If both RAM Areas Compare to the Pattern, the REC is 'OK'
Although some REC Failures are not so easily detected, many time they
may be determined by the Overall Test Results
* Example: BAD RAM Patterns for Bank 0 Match Bank 1
C128 / C128D HOST RAM
The Architecture of the 1700/1750 RAM Expansion Module requires an Area
of RAM within the C128 or C128D to be allocated. This RAM is referred
to as the Host RAM. Since the Test Data is first placed in this area and
Transferred to the RAM Expander for testing and back again, it is
necessary to insure that the Host RAM functions properly.
* The Host RAM is Tested using the C128/C128D Diagnostic Cartridge
* A Failure in the Host RAM will cause Incorrect Results to be displayed
during the RAM Expansion Test
RAM EXPANSION TEST
A Test Pattern is placed in the First Memory Location in Host RAM where
it is duplicated to fill the remaining area. When this is complete, the
Host RAM is Transferred to the RAM Expander. This Transfer Procedure is
duplicated until all Banks of the Expansion RAM are filled. After a Set
Time, to allow for Refresh, the Data is Transferred back to the Host RAM
and Compared to the Test Byte.
* If Data Read = Data Written - RAM is 'OK'
* If Data Read <> Data Written - RAM is 'BAD'
DYNAMIC RAM
Because the 1700/1750 RAM Expander uses Dynamic RAM, a Refresh Cycle
must occur at least every Two (2) Milliseconds. This is the Time Most
RAM Failures Occur.
* Each Test in the RAM Expansion Diagnostic allows for RAM Refresh
* Displayed Failures are Valid Only For The First Pass after which
Defective ICs should be Replaced and the Test Re-Started
* Further Testing will Display Incorrect Results
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