Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!princeton!caip!seismo!mcvax!philmds!prle1!prle2!slavenbg
From: slavenbg@prle2.UUCP (Gert Slavenburg)
Newsgroups: net.micro.atari16
Subject: Re: Anyone Else Had This Problem?
Message-ID: <8@prle2.UUCP>
Date: Wed, 28-May-86 03:32:47 EDT
Article-I.D.: prle2.8
Posted: Wed May 28 03:32:47 1986
Date-Received: Thu, 29-May-86 03:34:38 EDT
References: <8605200418.AA18920@ohio-state.ARPA>
Reply-To: slavenbg@prle2.UUCP (Gert Slavenburg)
Organization: Philips Research Laboratories Eindhoven
Lines: 44
Keywords: EPROM TOS
Summary: EPROM access time problems

In article <8605200418.AA18920@ohio-state.ARPA> terrell@OHIO-STATE.ARPA.UUCP writes:
>
>Once again my 520ST is screwed up.  This time every time I try to do just
>about anything with the control panel, the system reboots.  Often when I
>change the date, the background color near the cursor will be wrong.
>
Indeed this reminds me of a problem. Some time ago we massively installed
EPROM TOS (because ROM TOS was available late in Europe and secondly we don't
believe ROM TOS is bugfree enough yet). We used 250 nSec. access time EPROMs
based on the fact that a US component suppliers uses(used ?) those.

We found similar problems (you can't move the sliders of the control panel 
and closing the control panel often causes fail/reboot). 
Though Eric has no EPROM's, the similarity of the problems causes me
to suspect that your machine has access time problems on the ROM's, probably 
due to extreme tolerances of several components. In that case you better
exchange it !

General ADVICE on TOS EPROM's :
===============================

We found out that the critical requirement for ROM or EPROM's in the 520ST is 
that data out should be valid 200 nSec. after applying Chip Enable. The origi-
nal Atari ROM's are OK (of course).
If you have had EPROM's installed, you should verify the access time of the
particular type that your supplier gave you. 250 nSec. EPROM's do not meet the
requirements and may cause unexplainable system unreliability (like Eric has).
You do need 200 nSec access time EPROMs theoretically, although certain brands
or batches of 250 nSec EPROM's work. I wouldn't entrust my data to them though.
We are now using 200 nSec. access time 32k*8 CMOS EPROM's without problems.

Some confusing FACTS :

If you have too slow EPROM's you cannot find out by repeatedly checksumming or
otherwise testing the ROM area. Accessing them as data works fine. Executing
from them only causes these problem. (can you imagine the time we wasted !?)

Atari has a warning out that certain brands of EPROM's do not work. They do not
mention an access time problem, nor do they specify access time requirements. 
We found no brand related problems, just access time problems. 

Neil (@ Atari), I would like your comments.

  Gert Slavenburg