Acorn A500

[razz177]

Hi
I am new here so I hope I am in the right place.
I am going to be going through my acorn kit , doing power supplies & it looks like motherboards to thanks to battery leaks, anyway starting with my A500 done the caps in PSU and it turns on and boots now , revolving screen * in supervisor mode everything white is actually pink now, I need to get a mouse sorted any idea's on it I have an AMX mouse that I could convert but need a plug and pin connections, I also need to get it to boot from Hard Drive, I have also took pictures as I have stripped it down, I do know that it is running RiscOs 3

Now fitted new batteries and repaired battery holder, now a live wire has broken to the hard drive where something is inserted into it and shrink wrapped writing on it RS 2*2 2.2A there is not much there to solder to can you tell me what it is and where to get another one please.

Thanks for any help you can give me
Raymond

[a1exh]

Wowsers. Never seen a real A500. There must only be a handful ever made.

[razz177]

Wowsers. Never seen a real A500. There must only be a handful ever made.

Mine says 250 but I would imagine there are more, mine is very poorly but I am getting there fix one problem and get another.

pink screen & I need a mouse.

[a1exh]

Mine says 250

Ah. You mean R260? I've seen those. Never seen an A500

[Ronin47]

Wow, The Centre For Computing History suggests they were internal dev machines that were never sold to the public.

Hope you can fully revive it.

There's some interesting info here: https://chrisacorns.computinghistory.or ... /A500.html

[razz177]

Mine says 250

Ah. You mean R260? I've seen those. Never seen an A500

sorry I have not put that right the 250 is the serial number

[razz177]

Wow, The Centre For Computing History suggests they were internal dev machines that were never sold to the public.

Hope you can fully revive it.

There's some interesting info here: https://chrisacorns.computinghistory.or ... /A500.html

Thanks for the link I now know what the mouse looks like but cannot find it anywhere.
I suspect it might have come with a ps2 mouse as there is a ps2 socket on the front panel.

[SKS1]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

[IanS]

It's easy enough to make an adapter, this is the one I made when imaging this machine - https://www.domesday86.com/?page_id=936

a5000-mouse-connector.PNG (19.71 KiB) Viewed 725 times

I'm sure you can find the standard arc mouse pinout.

[danielj]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

Looks like it's wired straight onto those resistors on the PCB. I don't think it's a mouse port despite the connector...

[IanS]

Looks like it's wired straight onto those resistors on the PCB. I don't think it's a mouse port despite the connector...

Being so close to where the keyboard connector plugs into the PCB, it could be a connector for a standard arc keyboard.

[danielj]

Being so close to where the keyboard connector plugs into the PCB, it could be a connector for a standard arc keyboard.
a500-kbd.PNG

Ah, I was looking for a picture like that! Yes, that would seem much more likely.

[razz177]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

Yes it looks that way to me , it is wired to the board inside. the wires goto the resisters bellow in the picture.

[razz177]

It's easy enough to make an adapter, this is the one I made when imaging this machine - https://www.domesday86.com/?page_id=936
IMG_20171014_145111243_HDR.jpg
a5000-mouse-connector.PNG
I'm sure you can find the standard arc mouse pinout.

Hi seen this online and thinking of connecting to one of these number 1 looks the best to me what do you think ?

[razz177]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

No the only podule seems to be something to do with internet

[razz177]

Being so close to where the keyboard connector plugs into the PCB, it could be a connector for a standard arc keyboard.
a500-kbd.PNG

Ah, I was looking for a picture like that! Yes, that would seem much more likely.

just tried my RiscPc keyboard but that did not work

[SKS1]

Being so close to where the keyboard connector plugs into the PCB, it could be a connector for a standard arc keyboard.
a500-kbd.PNG

Ah, I was looking for a picture like that! Yes, that would seem much more likely.

just tried my RiscPc keyboard but that did not work

RISC PC keyboards are PS/2 where earlier ones are not (proprietary, so always been expensive).

[BeebMaster]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

No the only podule seems to be something to do with internet

Ah, it has a Master 128 PSU.

I heard about some early Archimedes using the Master power supply but I don't think I've ever seen one.

[Cruxinc]

A500s had a quadrature mouse input on the keyboard. See http://chrisacorns.computinghistory.org ... board.html

That socket looks like an aftermarket add-on. Is there a podule to support it?

No the only podule seems to be something to do with internet

Ah, it has a Master 128 PSU.

I heard about some early Archimedes using the Master power supply but I don't think I've ever seen one.

i worked on a 310 (or was it a 440 !) that had a master psu (i think) at the fixathon at tnmoc in november.
never seen another like it lol

[IanS]

Ah, it has a Master 128 PSU.

All A500's had a slightly modified Master PSU.

The modification was to add a yellow wire for the 12V supply, which is normally only available on the aux connector on a Master.
You can see the extra wire here - https://www.domesday86.com/wp-content/u ... _rear2.jpg

[razz177]

Ah, I was looking for a picture like that! Yes, that would seem much more likely.

just tried my RiscPc keyboard but that did not work

RISC PC keyboards are PS/2 where earlier ones are not (proprietary, so always been expensive).

I'll dig one out tomorrow and try an Archi one

[razz177]

Ah, it has a Master 128 PSU.

All A500's had a slightly modified Master PSU.
a500-psu.PNG
The modification was to add a yellow wire for the 12V supply, which is normally only available on the aux connector on a Master.
You can see the extra wire here - https://www.domesday86.com/wp-content/u ... _rear2.jpg

Yes mine has the yellow wire it is obvious that it has been put in afterwards as it has a different spade terminal.

[razz177]

Ah, it has a Master 128 PSU.

All A500's had a slightly modified Master PSU.
a500-psu.PNG
The modification was to add a yellow wire for the 12V supply, which is normally only available on the aux connector on a Master.
You can see the extra wire here - https://www.domesday86.com/wp-content/u ... _rear2.jpg

Yes mine has the yellow wire it is obvious that it has been put in afterwards as it has a different spade terminal.

Well that was strange followed the link and saw the serial number of 249 and mine is 250.

[razz177]

It's easy enough to make an adapter, this is the one I made when imaging this machine - https://www.domesday86.com/?page_id=936
IMG_20171014_145111243_HDR.jpg
a5000-mouse-connector.PNG
I'm sure you can find the standard arc mouse pinout.

I Have managed to find a mouse that works, after I ordered parts oh well

[razz177]

Ah, I was looking for a picture like that! Yes, that would seem much more likely.

just tried my RiscPc keyboard but that did not work

RISC PC keyboards are PS/2 where earlier ones are not (proprietary, so always been expensive).

I have tried two Archimedes keyboards in this socket neither of them worked, so this socket remains a bit of a mystery.

[SKS1]

just tried my RiscPc keyboard but that did not work

RISC PC keyboards are PS/2 where earlier ones are not (proprietary, so always been expensive).

I have tried two Archimedes keyboards in this socket neither of them worked, so this socket remains a bit of a mystery.

Not too surprised, as it may be an A500 build of RISC OS that does not support the quite-different Archimedes keyboard protocol.

In RISC OS 2 there were global variables A500Keyboard and A1Keyboard (Archimedes) that could control the variant being built.

[IanS]

Interesting, I hadn't realised the keyboard protocol was different.

From the post in the other thread, it looks to be a standard 3.10 rom, so curious how it works with the different keyboard
viewtopic.php?p=420163#p420163

Running RiscOs 3.10 30 April 1992

It looks like the FDC is different in the A500, is it compatible with the 1770?

[SKS1]

Interesting, I hadn't realised the keyboard protocol was different.

See "F0" in https://www.binarydinosaurs.co.uk/Museu ... ellows.php. This story actually related to when we received the first Archimedes protocol keyboard. A500 one just worked pretty quickly, but the Arc one had been outsourced.

From the post in the other thread, it looks to be a standard 3.10 rom, so curious how it works with the different keyboard
viewtopic.php?p=420163#p420163

Running RiscOs 3.10 30 April 1992

If they were still supporting A500s, which clearly they must still have been doing, I think it was possible to build a kernel that supported either keyboard.

Would have made sense to build an A500 image at the same time as all the other 3.1 images for A310 thru A5000.

It looks like the FDC is different in the A500, is it compatible with the 1770?

Don't think so? Not my area. Haven't see the A500 circuit diagram since 1988 . It did have a higher density mode that we never got to work reliably.

[Pernod]

From the post in the other thread, it looks to be a standard 3.10 rom, so curious how it works with the different keyboard
viewtopic.php?p=420163#p420163

Running RiscOs 3.10 30 April 1992

It looks like the FDC is different in the A500, is it compatible with the 1770?

We already have an A500 RISC OS 3.10 (30 Apr 1992) ROM dump that is definitely different from the standard Archimedes RISC OS 3.10, it came from an A500 with serial #47, see viewtopic.php?p=333017#p333017.

[baz4096]

The FDC on the A500 was either 9793 or 1793 according to the TRM I think.