Re: DD2 & 3

From: Nicolas Welte <>
Date: Wed, 19 Jun 2013 10:24:53 +0200
Message-ID: <>
On 18.06.2013 23:58, wrote:
>> The same PCB was also used in the 1570 and 1571 versions of DD3, and even in the C128DCR version. The DCR drive has no free I/O lines at all, and the 1570/71 has only free lines on the CIA chip. To avoid having a different PCB for each 1541 version, and also for each 1570/1571/C128D/C128DCR version, they used the approach with the 6821 PIA.
> I know that 1571 version existed but I have never seen it, let alone DCR version! Do you have access to those?

I own an orignal set for the C128DCR with German keyboard. AFAIK, the ROM 
is the same for the normal 1571, because DD3 does not support MFM mode at 
all. So different ROM versions are not necessary.

I don't have the 1570 version unfortunately.

There is one difference for the 157x/DCR versions, though: they are 
externally clocked with 2MHz speed, while the 1541 versions runs at 1MHz 
only. So it might be interesting to install your board in a 1571 and see 
how it behaves :)

Unfortunately DD3 on the 157x drives uses 2MHz all the time to improve 
loading speed, even in 1541 mode! This breaks compatibility with most 
custom loaders, so you end up disabling the board with @X- most of the 
time, if you want to load multi file games or watch demos.

An improvement could probably be made by porting the DD3 ROM of the 1541 to 
the 1571 ...

I noticed that the C128 kernal was based on the old 1985 kernal version, so 
I created a version with all the recent patches of the 1986 version, so it 
matches the C128 BASIC ROMs better.

BTW, do you know about the arm2iec SD card drive? It also supports the 
Dolphin DOS parallel cable, and the loading speed is unbelievably fast 
(IIRC less than 2 seconds for 202 blocks on C64)!

So you can build a nice Dolphin DOS system now with your boards, and have 
fast access to SD cards :)


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Received on 2013-06-19 09:00:03

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