Atom 1770 ADOS by Bearsoft

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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herklots
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Atom 1770 ADOS by Bearsoft

Post by herklots » Fri May 17, 2013 3:57 am

Here's the Bearsoft 1770 FDD system for the Atom, c. 1985.

DFS compatible...

Attached:
Hardware manual
Schematic
Software manual
ROM targetted E000
My disassembly with thoughts to relocate it
FORMAT program
My regeneration of FORMAT, FORMATA, to allow it to be relocated

What's a floppy anyway?

Tim
Attachments
Bear 1770 ADOS .zip
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danielj
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Re: Atom 1770 ADOS by Bearsoft

Post by danielj » Fri May 17, 2013 8:35 am

Never even slightly aware of this. Do you have one?

d.

herklots
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Re: Atom 1770 ADOS by Bearsoft

Post by herklots » Fri May 17, 2013 2:44 pm

Yes, it's on a Eurocard. Most of the circuit is redundant address selection stuff.

Tim

Prime
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Re: Atom 1770 ADOS by Bearsoft

Post by Prime » Fri May 17, 2013 9:05 pm

Indeed you could prolly get it down to a half Eurocard by using a couple of PALs...heck you could even put an extra 32K of memory on there :)

And no I'm not saying I'll do this.

Cheers.

Phill.

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oss003
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Re: Atom 1770 ADOS by Bearsoft

Post by oss003 » Mon May 27, 2013 10:14 am

Hi guys,

I contacted Mike Barwise (Bearsoft) and asked him if he still has some soft-/hardware info for the Atom and if he's willing to publish it. He's now into nature sound recording http://www.wildsoundscape.co.uk
His reaction is attached below.

Greetings
Kees
Mike.png
Mike.png (22.51 KiB) Viewed 581 times

BillG
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Re: Atom 1770 ADOS by Bearsoft

Post by BillG » Mon Jul 20, 2015 9:10 pm

I've attached a couple of pictures of my Bear 1770 board now working in a 19 inch rack, as requested by Roland. It seemed to fit best with this older post rather than mine. Hope this is of interest.
Attachments
Bear 1770 bottom.jpg
Bear 1770 top.jpg

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Pernod
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Re: Atom 1770 ADOS by Bearsoft

Post by Pernod » Thu Aug 30, 2018 6:29 pm

Has this card been reverse engineered? The manual states it's decoded at &FF8-&FFD, and from the schematic I'd say the 1770 is at &FF8-&FFB.

The ROM also accesses &FFC-&FFD, anyone know details of these two registers? A typical 1770 implementation would only use a single register.
- Nigel

BBC Model B, ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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roland
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Re: Atom 1770 ADOS by Bearsoft

Post by roland » Thu Aug 30, 2018 6:36 pm

BillG wrote:
Mon Jul 20, 2015 9:10 pm
I've attached a couple of pictures of my Bear 1770 board now working in a 19 inch rack, as requested by Roland.
Did I :?: Thanks anyway - I've never seen this interface before.
256K + 6502 Inside
MAN WOMAN :shock:

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Pernod
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Re: Atom 1770 ADOS by Bearsoft

Post by Pernod » Fri Aug 31, 2018 9:55 pm

Can anyone help with interpreting the schematic?
Bear 1770 FDC schematic.png
Here's what I think I know, please correct me if I've got anything wrong.
Address decoding can be set with links but ADOS ROM provided is configured as follows:

Code: Select all

&FF8-&FFB RW WD1770
&FFC      R  DSTR - reads drive step rate from links PB6, I return &FC for 6mS (depends on drive selected on D0,D1).
&FFC       W RSTW - performs reset of WD1770. ADOS writes various values to this address (F8, F9, FA, FB, FC, FD, FE, FF) so am thinking it also selects current drive and side, assuming the link to LS175 is made?
&FFD      R  PSRR - What could PSR stand for? I have this returning the status of the INT/DRQ lines in D6/D7, current drive in D0/D1, and links PB5 in D2 which indicates whether current drive is double sided.
&FFD       W PSRW - I only see &D0 being written here, is it only setting DEN?

Not sure whether I need to do anything with the BIND line.
0011.png
Last edited by Pernod on Fri Aug 31, 2018 10:05 pm, edited 1 time in total.
- Nigel

BBC Model B, ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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