Re: P500

From: Steve Gray <sjgray_at_rogers.com>
Date: Tue, 6 Nov 2012 13:51:44 -0800 (PST)
Message-ID: <1352238704.91208.YahooMailNeo@web161303.mail.bf1.yahoo.com>
Hi,
 
The P500 roms should be considered BETA. There must have been some hardware issues in the early prototypes because commodore had to put in a loop in the screen writing routine. IE: write a byte, loop until you verify the write was successful. Luckily they seem to have got the hardware fixed, but apparently forgot to remove the loop. 
 
Here's some info:
http://www.davidviner.com/cbm3.html?name=Discoveries+Part+2
 
It says the loop can be removed and will double the speed of screen writes...
 
At some point I was hoping to patch the ROMs and release an updated kernal. It should be fairly trivial. Here's a disassembly of the rom:
http://www.von-bassewitz.de/uz/oldcomputers/p500/rom500.s.html
 
Steve
 

>________________________________
> From: Christian Dirks <Toast_r@IdeaLine.info>
>To: cbm-hackers@musoftware.de 
>Sent: Tuesday, November 6, 2012 4:15:04 PM
>Subject: P500
>  
>Hi,
>a few days ago I got a P500 mainboard.
>The brun-in test showed a bad DRAM in bank 2, but only because it was a bit loose in it's socket.
>Someone soldered sockets to bank 2 and 3 and populated it with DRAMs.
>The test does not show errors anymore, but I think there maybe some issue.
>The screen scrolling seems very slow to me.
>Since I haven't seen a working P500 before, I don't know, if it is alwas that slow.
>The ROMs are -02's.
>
>Does anybody have a spare case and/or a psu (230V) which he could offer ?
>
>Is there any software around beyond the burn-in program ?
>
>-- Christian Dirks
>Toast_r@Idealine.info
>
>
>
>      Message was sent through the cbm-hackers mailing list
>
>
>   

       Message was sent through the cbm-hackers mailing list
Received on 2012-11-06 22:00:56

Archive generated by hypermail 2.2.0.