RE: 9060/9090

From: didier derny <>
Date: Wed, 25 Dec 2013 10:10:03 +0100
Message-ID: <000301cf0151$19576390$4c062ab0$@org>
Thanks, now it's clearer 

I'm disassembling the rom found on zimmer (the sasi part)

I'm trying to find the memory map from the schematics 
(not so easy to read, problem of quality)

Till now I found:

- 6502
- 6522 ????        
- 2716 $F800  (a part is not used)
- 6810 ????

Apparently the 6522 is connected to 2 jumper on PB4/PB5 (according to the
pin number)

No idea of the use of these jumper ?  hard disk selection 9060/9090
I think I've found all the chip select... decoding...

-----Message d'origine-----
De :
[] De la part de Ethan Dicks
Envoyé : mercredi 25 décembre 2013 04:39
À :
Objet : Re: 9060/9090

On Tue, Dec 24, 2013 at 4:55 PM, didier derny <> wrote:
> I’m playing with sasi recently and I’m looking at the schematics of
> 9060/9090 (taken from


> Any idea of what really is the  component between the 6522 and  the 
> 2716 The number written is either 5810 (most probably) or  9810  it has 24
> Is it a 128 byte ram ?

Yes.  It's really a 6810 Motorola 128 byte SRAM.

> Apparently the most interesting software is In this 2716…

There are two sets of firmware in there (two CPUs).  One talks to the PET
via IEEE and understand CBM DOS commands, the other talks to the SASI board,
and they have a patch of SRAM for shared data.

> Any idea if a source code exist for this rom ?
> I would like to extract the sasi commend really send by this board

There may be some manual disassembly out there, but I do not think it's as
extensive as for the BASIC and KERNAL ROMs


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Received on 2013-12-25 10:00:04

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