[Techtoolslist] Jedi RAM testing

[John Robertson]

Danny Pearson wrote:

> Hi, I've got a noob question regarding ram testing and using the 9010.   I'm

> trying to build a script to do some basic testing on Return of the Jedi

> using a known working board as a benchmark.  So far I'm just concentrating

> on the main CPU, not the sound CPU and I've got the ROM test all working,

> now I'm moving on to the RAM.  The schematics for Jedi list a ram area at

> 2400-27FF as Scrolling Playfield(high) and this appears to me to only have 4

> data bits.   If you run the built in RAM test on the Fluke for this area it

> fails, and from what I've managed to glean from the reading I've done this

> is as it should be as only 4 bits of data area are returned (a nibble?),

> whereas I assume the RAM test algorithm uses a whole 8 bits (byte).   I've

> written the following script to exercise this (and other similar RAM areas).

> Can you tell me if I'm on the right lines?   So far I've never done anything

> other than the built in 9010 tests so forgive me if this is a stupid

> question;

>

>       REG1 = 2400

> 1:	!LABEL 1

> 	IF REG1 = 2800 GOTO 3

>       WRITE @ REG1 = FF

>       WRITE @ REG1 = AA

> 	READ @ REG1

> 	IF REGE = FA GOTO 2

> 	dpy Failed Response = $1 = $E

>       aux Failed Response = $1 = $E

> 	GOTO 3

> 2:    !LABEL 2

> 	aux Success Response = $1 = $E

> 	INC REG1

> 	GOTO 1

>

> 3:     !LABEL 3

> 	dpy TEST COMPLETE

> 	aux TEST COMPLETE

>

>

> Cheers,

>

> Dan

>

>   

Looks like a good solution to the problems encountered with other 4-bit 
RAM (2101/5101/etc.) as well. However your test should include (at a 
minimum) F5 and FA to check that bits aren't locked.

However if you only use FA and F5 then you have no way of finding stuck 
address nodes.
 
So it wouldn't hurt to add an offset count  - something like F0, F1, F2, 
F3, F4, F5, F6, F7...FE, then skip one space and run that again - this 
is to try and catch data/address rows or columns that are stuck - trying 
to check that bits in (for example) location 000h are not the same as 
location 010h which can happen if RAM internal (or external) addressing 
has problems.

John :-#)#

-- 
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
                 www.flippers.com 
"Old pinballers never die, they just flip out"