Page Comparison

RAM Test

Cambridge Computer wrote a BBC BASIC program to test RAM.

Image Added

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 (<> Image Added CARD). For example, you may have a 512K Ram RAM card in your Z88 but (<> Image Added CARD) reports that you only have 128K. Failure of the RAM falls in into 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 packsRAM cards.

It This is what is called a destructive Ram Test which means that all RAM Test. All the data that is stored on in the RAM card will be destroyederased.

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,

Image RemovedImage Added

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 Save onto an EPROM with card the BOOT.CLI and RAMTEST.BAS files.
		Back-up all your files.
Image Modified		Open the card flap Remove the current RAM card.
Image Modified		Insert the EPROM card in slot 3
		Do a Hard Reset. The memory test program will be fetched and Leaving the card flap open, do a Hard Reset.  Close the card flap The BOOT.CLI program will run, the memory test programs will be fetched from the EPROM card and then will start to run. Image Modified
		Image Modified When you get the Command line type in the number of K the ram RAM card is. E.g. 1024 Image Modified
Image Modified		Insert the RAM card to be tested in Slot 1.
		Image Modified Press the ENTER Image Added key until you get the "Testing . . . " message. Whilst this is testing, tap underneath the Z88 where the card is installed to expose any mechanical electrical problems with the card connector and/or any dry solder joints in the card itself.
		Image Modified When the test is finished,
Image Modified		Remove the EPROM pack and
		Do another Hard Resetanother Hard Reset.
		To make sure that the memory is alright, load a large text file into Pipedream and see if you can read the whole file.

Supply Voltage Min

2.7

Input High Voltage

0.7 x VCC min

to VCC+0.3

2.2 to VCC+0.3

2.4 to VCC+0.3

2.4 to VCC+0.5

2.2 to VCC + 0.5 V

Input Low Voltage

0.5 to 0.8

-0.5 to 0.8

- 0.2 to 0.6

- 0.2 to 0.6

Output High Voltage

2.4 min

Output Low Voltage

0.4 max

0.4 max

0.4  max

Standby Power 

3.5 to 50

VCC for Data Retention

Chip Enable Access Time tACE 

Output Disable to Output in High-Z tOHZ

18 max 

Output Hold from Address Change tOH

Write Cycle Time tWC

Address Valid to End of Write tAW

35 min 

Chip Enable to End of Write tCW 

35 min

Address Set-up Time tAS 

Write Pulse Width tWP 

Write Recovery Time tWR 

Data to Write Time Overlap tDW 

Data Hold from End of Write Time tDH 

Data Setup to Write End

25 min

Output Active from End of Write tOW 

Write to Output in High-Z tWHZ