Pegasus 400 Disc Interface Electron

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TheCorfiot
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Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Fri Dec 27, 2019 7:36 pm

Hi Guys

Would anyone have the schematic for the Acorn Electron Pegasus Disc Interface Please..

I've got one here working perfectly with DFS but fails to Recognise any ADFS ROM.

Cheers
Bas ;)

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Arcadian
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Re: Pegasus 400 Disc Interface Electron

Post by Arcadian » Fri Dec 27, 2019 7:44 pm

Phill HS produced these back in 2011 - are they what you need?
viewtopic.php?f=3&t=3787
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MadeGray
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Re: Pegasus 400 Disc Interface Electron

Post by MadeGray » Sat Dec 28, 2019 10:49 am

That’s interesting,

I’ve one here that does exactly the same thing / however I’m convinced it’s the plus one.

I tested ADFS in a separate plug in cartridge electron cartridge and found that had the exact same problems. Also depending on the version of ADFS sometimes parts would show at least. This depended on where I’m the 16k the code was in the ROM

My testing revealed that the plus 1 couldn’t recognise 16k roms however as DFS was 8k worked perfect. I tried other 16k ROMS had the same problem was being shown.

I’m sure there is a decode logic problem on my Plus 1

I’ve bought new replacement logic chips for the plus 1 but not had time to check or swap them yet.

So - is try some other 16k roms to see if same issue or like I did drop adfs into an external cartridge.

Could help solve both our issue!

John
John Gray

BBC Master x2 with BeebSCSI, PI copro etc and lots of Goteks. A few Model B’s and a trusty Elk. Won’t mention the ZX80 and ZX81!

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CMcDougall
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Re: Pegasus 400 Disc Interface Electron

Post by CMcDougall » Sat Dec 28, 2019 11:20 am

sure this has been asked before,

Yip, found :
viewtopic.php?f=3&t=16154&hilit=Pegasus+dfs+adfs

Or just put ADFS in the bin =D>
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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Sat Dec 28, 2019 12:29 pm

Cheers Colin

Cant see a schematic anywhere though ?

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rmbrowngr
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Re: Pegasus 400 Disc Interface Electron

Post by rmbrowngr » Sat Dec 28, 2019 12:47 pm

I have ADFS Electron version 1 working just fine with the Pegasus 400, but I have ADFS in my AP5 socket 12.

Just reading, this page https://www.retro-kit.co.uk/page.cfm/co ... gasus-400/ and the manual does state that you can fit a suitable ADFS ROM in the spare socket.
The Slogger Pegasus 400 disc interface however supported both DFS and ADFS by the fitting of suitable ROMs to the card and allowed a user to choose the type of floppy drive they attached to the standard 34-pin socket.
Regarding ROM size, I see that you may need to alter the jumper settings to get 16k. viewtopic.php?t=11757#p149796. But if you select 16k you'll going to lose RAM and I guess page for DFS will not be at E00. Each socket can be configured individually for RAM\ROM.
Richard B
Acorn Electrons issue 4 and 6, MRB, Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi, GoSDC MBE.
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1024MAK
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Re: Pegasus 400 Disc Interface Electron

Post by 1024MAK » Sat Dec 28, 2019 1:45 pm

TheCorfiot wrote:
Sat Dec 28, 2019 12:29 pm
Cheers Colin

Cant see a schematic anywhere though ?
In the zip file in the first post of the thread that Arcadian linked to in his post above...

Richard has corrected his post just above this one.
DFS or ADFS ROMs can be fitted in either of the ROM sockets on the Pegasus interface. However each ROM socket has it’s own group of selection links (jumper shunts) to decide if that ROM slot is all seen by the CPU (16k bytes of ROM), or if part of that slot is replaced with RAM. Only special DFS or ADFS ROMs (images) that are designed to work with part of the slot being RAM will work in this configuration (these use the RAM on the Pegasus interface for work space and so don’t use main memory). So if a standard Acorn DFS or ADFS is used, that will use main memory as work space, so the selection links (jumper shunts) must then be set for 16k ROM only.

Mark

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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Sat Dec 28, 2019 5:18 pm

Hi everyone

Thank you so much for the support... finally saw the link for the schematic lol

I built 2 boards, one works perfectly ADFS and DFS the other has this ADFS issue, jumpers set the same on both boards.

Pretty sure I have a trace or via issue but thanks to the schematic should be able to fix it now.

Happy NewYear all

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Re: Pegasus 400 Disc Interface Electron

Post by CMcDougall » Sat Dec 28, 2019 7:42 pm

/\ same to you Baz 8)

have fun finding the short on via V trace, it's under the sockets :cry:
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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Sun Dec 29, 2019 2:35 pm

Started looking into this this morning chaps and found some funny results lol

The board is configured as follows
28 Pin Sockets L-R are PEGDFS , ADFS, 6264SRAM, 1772

Jumpers L-R are D, U,U,D

Which seems great....

Plug board in and ADFS works absolutely fine... DFS Rom is not even recognised by *ROMS
Remove the ADFS ROM from the Socket and DFS is now recognised and it works absolutely fine... E00 as well.

Been round looking at traces no shorts found or open tracks. I can confirm all the IC's work as I substituted them into my Pegasus400 and all worked as it should.

Work that one out lol

:)

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Re: Pegasus 400 Disc Interface Electron

Post by daveejhitchins » Sun Dec 29, 2019 3:47 pm

TheCorfiot wrote:
Sun Dec 29, 2019 2:35 pm
Started looking into this this morning chaps and found some funny results lol

The board is configured as follows
28 Pin Sockets L-R are PEGDFS , ADFS, 6264SRAM, 1772

Jumpers L-R are D, U,U,D

Which seems great....

Plug board in and ADFS works absolutely fine... DFS Rom is not even recognised by *ROMS
Remove the ADFS ROM from the Socket and DFS is now recognised and it works absolutely fine... E00 as well.

Been round looking at traces no shorts found or open tracks. I can confirm all the IC's work as I substituted them into my Pegasus400 and all worked as it should.

Work that one out lol

:)
One thing that I've found with the Pegasus PCBs that were recovered by Dave (Arcadian) is that the vias* are the likely suspects for any board failures. I have a few myself that are waiting repairs.

* Vias are the holes that carry traces from one side of the PCB to the other. They are plated with copper to make the connection. Unfortunately this 'batch' of Pegasus PCBs aren't made very well and some of the vias are very poorly made! The cure - fit a wire link!

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ARA III, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Mon Dec 30, 2019 10:30 am

I will check the vias out today Dave...

Just confused as to why the ADFS ROM stops the DFS ROM being seen when its plugged in.
Removing the ADFS ROM sows DFS in slot zero
Plugging in ADFS its seen in slot 1 but slot zero is now empty.

All disc functions work perfectly when either rom is active....

Doh

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Re: Pegasus 400 Disc Interface Electron

Post by daveejhitchins » Mon Dec 30, 2019 10:46 am

TheCorfiot wrote:
Mon Dec 30, 2019 10:30 am
I will check the vias out today Dave...

Just confused as to why the ADFS ROM stops the DFS ROM being seen when its plugged in.
Removing the ADFS ROM sows DFS in slot zero
Plugging in ADFS its seen in slot 1 but slot zero is now empty.

All disc functions work perfectly when either rom is active....

Doh
It could be just the ROM switching logic is faulty somewhere due to the above ^^ via situation (?)

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ARA III, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Mon Dec 30, 2019 5:09 pm

Well All Via's are good, all tracks confirm good. Cant find any shorts.

What I can confirm though is that the 2nd ROM socket, controlled by the right jumper block does not allow the SRAM to be mapped inplace of part of the Pegasus DFS ROM, so although fitting just the DFS ROM in the 2nd socket I cant get the SRAM overlay but the ROM is seen by *ROMS

losing the will slowly but surely lol

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Re: Pegasus 400 Disc Interface Electron

Post by daveejhitchins » Mon Dec 30, 2019 10:25 pm

t.png
This is the area you need to look at - including the links!


Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ARA III, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: Pegasus 400 Disc Interface Electron

Post by daveejhitchins » Mon Dec 30, 2019 10:31 pm

And the link settings from the User guide.
Untitled.png

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ARA III, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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TheCorfiot
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Re: Pegasus 400 Disc Interface Electron

Post by TheCorfiot » Wed Jan 01, 2020 9:28 am

Already been through that, all checks out lol

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