Page Comparison

RAM Test

Cambridge Computer wrote a BBC BASIC program to test RAM. Unless the memory is good the Z88 will become unstable, the FAIL indicator may appear in the top right-hand corner of the display or inconsistent results will occur when checking the size of the RAM with (<> CARD). For example, you may have a 512K Ram card in your Z88 but (<> CARD) reports that you only have 128K. Failure of the RAM falls in the following categories.

• Mechanical failure - due to the contacts being dirty or from a dry soldered joint
• Unsuitable memory chip - if a different chip is used it may not have the identical specification to the one previously used.

Running the BASIC program while `tapping' the RAM pack may identify a mechanical failure. Finding other errors can be difficult.

The other sort of memory failure is where certain bits of memory suffer amnesia when you are not reading or writing to the memory.

This is like when you are just storing files in the RAM.

This fault can be found with any program, (zCheck, Zip, Unzip (Z88 Forever) or SqueeZ~88 (Rakewell)) that uses checksums on files. To use it you should:-

1. Run the program initially so that the checksums of the files are calculated. If you are using SqueeZ~88 or Zip, squeeze/Zip a load of big files.
2. Turn off the Z88 and leave it alone for about three to five days.
3. Re-run the program to see if the checksums of the files are different or unsqueeze/Unzip all the files again. If they are, then the RAM where the file was stored is faulty.

The following BBC BASIC program tests 32K, 128K 512K and 1MB Ram packs.

It is what is called a destructive Ram Test which means that all the data that is stored on the RAM will be destroyed.

Download the 4 files zipped, (original instructions, two .CLI files (which do the same thing) and the memory test software from here, and then transfer them to your Z88 with a transfer program. If the CLI file is in an EPROM in slot 3,

There are two ways you can use this program.

1. Just running the BBC BASIC program (Ramcard.bas)
2. Before using the program you should save the program to EPROM as "RAMTEST.BAS" and write the following BOOT.CLI to use with it. This will load and run the program automatically after a HARD RESET is given.

#F
|EF
RAMTEST.BAS~E~E
#B
CHAIN
"RAMTEST.BAS"~E

To use the memory test, follow these steps:-

Image Modified		Load an EPROM with the BOOT.CLI and RAMTEST.BAS files.
		Back-up all your files.
Image Modified		Remove the current RAM card.
Image Modified		Insert the EPROM in slot 3
		Do a Hard Reset. The memory test program will be fetched and will start to run.
		When you get the Command line type in the number of K the ram card is. E.g. 1024
Image Modified		Insert the RAM card to be tested in Slot 1.
		Press the ENTER key until you get the "Testing . . . " message.
		When the test is finished,
Image Modified		Remove the EPROM pack and
		Do another Hard Reset.