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ICL OPD
Posted: Thu Jun 13, 2019 9:49 am
by Pr0f
Not sure if this is considered a compatible, but it does share some common hardware components.
Acquired a motherboard and processor board for this recently - does anyone have a service manual or circuit diagrams for this beasty?
Or perhaps have any details for the pin outs for the ROM card at the backup - is it even remotely similar to the QL 64 way connector pin outs ?
If not, I guess I've got some nice long hours of multimeter ping testing to find out what's connected where...
Seems to be a good few '138 decoders on board for a machine that's laden with ROM chips
Re: ICL OPD
Posted: Thu Jun 13, 2019 9:49 am
by Pr0f
Pr0f wrote:Not sure if this is considered a compatible, but it does share some common hardware components.
Acquired a motherboard and processor board for this recently - does anyone have a service manual or circuit diagrams for this beasty?
Or perhaps have any details for the pin outs for the ROM card at the back - is it even remotely similar to the QL 64 way connector pin outs ?
If not, I guess I've got some nice long hours of multimeter ping testing to find out what's connected where...
Seems to be a good few '138 decoders on board for a machine that's laden with ROM chips
Re: ICL OPD
Posted: Thu Jun 13, 2019 9:52 am
by vanpeebles
I think the OPD is part of the QL family
Re: ICL OPD
Posted: Thu Jun 13, 2019 11:16 am
by Pr0f
It certainly has some QL pedigree - featuring both the ULA's from the QL
Also 2 microdrives.
It's a different OS though, and had it's own bespoke monitor which also powered the board.
I am wondering how much work would be involved in making the board work like a QL, but in any case it would be a good platform for testing out a potential ZX8301 replacement.
Re: ICL OPD
Posted: Thu Jun 13, 2019 1:47 pm
by dilwyn
Pr0f wrote:Not sure if this is considered a compatible, but it does share some common hardware components.
Acquired a motherboard and processor board for this recently - does anyone have a service manual or circuit diagrams for this beasty?
Or perhaps have any details for the pin outs for the ROM card at the backup - is it even remotely similar to the QL 64 way connector pin outs ?
If not, I guess I've got some nice long hours of multimeter ping testing to find out what's connected where...
Seems to be a good few '138 decoders on board for a machine that's laden with ROM chips
Some info here:
https://rwapsoftware.co.uk/oneperdesk/t ... _info.html
I looked into the situation with OPD manuals some time ago at the request of someone else and found that scarcity of documentation is at least partly down to the fact that copyright clearance seems not to have been given for the OPD manuals. Certainly a quick googling for OPD manuals or PDFs seems to turn up nothing that is free.
Re: ICL OPD
Posted: Thu Jun 13, 2019 2:01 pm
by Pr0f
I know - it's a bit of a lost cause.
I know it was marketed as a Merlin Tonto M1800 - and I came across this little gem:
http://www.binarydinosaurs.co.uk/Museum ... riteup.php
and there is a link to this manual:
http://www.samhallas.co.uk/repository/p ... _tonto.pdf
which gives a bit more, but struggling to find a document with hardware addresses or memory map which would be a start...
Re: ICL OPD
Posted: Thu Jun 13, 2019 2:04 pm
by Pr0f
dilwyn wrote:Pr0f wrote:Not sure if this is considered a compatible, but it does share some common hardware components.
Acquired a motherboard and processor board for this recently - does anyone have a service manual or circuit diagrams for this beasty?
Or perhaps have any details for the pin outs for the ROM card at the backup - is it even remotely similar to the QL 64 way connector pin outs ?
If not, I guess I've got some nice long hours of multimeter ping testing to find out what's connected where...
Seems to be a good few '138 decoders on board for a machine that's laden with ROM chips
Some info here:
https://rwapsoftware.co.uk/oneperdesk/t ... _info.html
I looked into the situation with OPD manuals some time ago at the request of someone else and found that scarcity of documentation is at least partly down to the fact that copyright clearance seems not to have been given for the OPD manuals. Certainly a quick googling for OPD manuals or PDFs seems to turn up nothing that is free.
Bingo - that link on the RWAP site gives a memory map
Happy days
Re: ICL OPD
Posted: Thu Jun 13, 2019 2:59 pm
by RalfR
I wish, I had known the modifications to generate a standard composite output, when I once bought my OPD from TF. The monitor, he sent with it was broken, so I modified my CUB to run with the OPD. But that means, it does not run with the QL any longer and heaven knows, what I have changed there 10 years ago...
--------- snip ---------
6. HOME BREW MODIFICATION OPTIONS
The following changes can be made:
6.1 Change IC34 from a 74LS240 to a 74LS244 to invert the video & sync. outputs from the main board to allow the use of a standard monitor
6.2 Connect TP3 to pin 15 of J3 (solder pad above Q7) to provide a composite sync. signal for a monitor
Re: ICL OPD
Posted: Fri Jun 14, 2019 10:05 am
by Pr0f
Some other mods i am considering:
I plan on changing the address decoding on the CPU module so that the ROMS occupy the first 64K/96K/128K address space
Remove the 2 Sinclair ULA's carefully, and solder in sockets and do the same for the databus transceiver and address mux's too - means I could potentially replace these with a plug in module to experiment with different video options Looks like the 128K of RAM is actually in the same place in the memory map. Some juggling of the I/O addresses and effectively it's a QL... But a QL with lots of places to plug in various things
Re: ICL OPD
Posted: Fri Jun 14, 2019 5:58 pm
by Dave
You planning to turn it back into a novel QL?
First, check the keyboard matrix is the same. I think it might be different.