a DIY home build project...

The Thor, Aurora, Q40 and Q60 etc. are discussed here.
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Re: a DIY home build project...

Postby Dave » Sat Jan 06, 2018 12:05 am

Peter wrote:And 90% overlap with the Q68... just a matrix keyboard converter, and you're mostly done. ;)


The 10% being expansion. Funny thing - there will be an expansion for the Q68 sooner than you might think.

The serial is +/-5v, right? :D


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Re: a DIY home build project...

Postby Pr0f » Sat Jan 06, 2018 11:03 pm

2 SD card adaptors fit nicely in the top of the QL case, the SD card slot fits quite well in the Microdrive slot. The only down side is the SD card would be upside down.
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Re: a DIY home build project...

Postby Dave » Sun Jan 07, 2018 1:59 am

If you replace those IDE connectors with right angle connectors, they'll go the right way up too.


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Re: a DIY home build project...

Postby Pr0f » Sun Jan 07, 2018 4:11 pm

I did wonder about that too, but the only way they can really fit is if I remove the power connectors and 40 way IDE connector and mount them on the other side. I am happy to live with them upside down, as it's a lot less work...


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Re: a DIY home build project...

Postby Dave » Mon Jan 08, 2018 12:02 am

You'd just need to remove the HD power connector, because it's duplicated in the floppy power connector.

Would you be interested in emailing privately?


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Re: a DIY home build project...

Postby Pr0f » Mon Jan 08, 2018 7:17 am

Dave wrote:You'd just need to remove the HD power connector, because it's duplicated in the floppy power connector.


There is possibly only a few mm between the pcb and upper case, so all the large connectors would need to be removed - as you say, I only need one power connector, but even the 4 pin floppy power connector is too deep for the SD cards to align in the slot correctly. The big 40 way IDE will definitely have to come off and go the other side.

It is do-able.

Dave wrote:Would you be interested in emailing privately?


PM sent :-)


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Re: a DIY home build project...

Postby Pr0f » Mon Jan 08, 2018 7:42 am

One of my goals with the DIY project is to try and make the new design work with old plug in cards - provided they follow the Technical Guide specs. Any cards that were built that way will have position independent code, and will also be able to locate their hardware based on the address they find themselves at. This works to my advantage, because although these cards would nominally have been sat at 0xc000 in the original QL memory map, I will control the A18 and A19 lines on the edge connector, such that unless the bus is granted (an external processor card, such as Gold or my equivalent is on the edge connector), these lines will only go high together when the address in the expanded 4MB map matches A21=1, A20=1, A19=1, A18=0 (this puts the expanded cards at 0X38000) That's necessary to move it 256K down the memory map to allow for the VRAM area to be sited in the top 256K.

As long as the code in the ROM to look for expansion cards knows about this change, it will look for Expansion ROMs there.

One final trick I intend to use is to normally have RAM shadowed FLASH ROM in that address space, but filled from the top of that 256K block, with I/O cards filling it from the bottom if they are present. I/O cards will take priority over ROM, but if none are plugged in, the entire space can be filled with RAM or ROM as desired.

My first sub project will be to replace the 8049 with a propeller chip and support logic, to provide QL keyboard, sound and PS/2 keyboard and mouse. I can change the part of the code that talks to the rest of the QL independently of the keyboard and sound routines - note - I won't be porting the QL serial port logic over to the propeller - the DUART chip will handle that. But doing it this way means I can test the propeller logic in a standard QL so I know it works before moving it over to the new machine.

My second sub project will be to create the graphics engine as a plug in card, again so I can test the design in a standard QL.


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Re: a DIY home build project...

Postby Peter » Tue Jan 09, 2018 10:58 am

Dave wrote:
Peter wrote:And 90% overlap with the Q68... just a matrix keyboard converter, and you're mostly done. ;)

The 10% being expansion. Funny thing - there will be an expansion for the Q68 sooner than you might think.
The serial is +/-5v, right? :D

Yes, it uses a MAX3311E supplied with 5V.


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Re: a DIY home build project...

Postby Peter » Tue Jan 09, 2018 11:05 am

Pr0f wrote:My first sub project will be to replace the 8049 with a propeller chip and support logic, to provide QL keyboard, sound and PS/2 keyboard and mouse.

Would you emulate the 8049 on a chip level, or try to implement it's QL specific communication interface?


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Re: a DIY home build project...

Postby Pr0f » Tue Jan 09, 2018 12:01 pm

The initial idea would be to put a small 40 pin board in place of the 8049, and connect the relevant pins to the propeller - QL keyboard is just 16 lines, as the existing diodes can still be used. As the propeller is a 3.3v device, I can put protection in for the pull up's, so the propeller won't need anything fancy to handle the QL keyboard. A single cog would handle reading the keyboard. I would use another cog to handle the PS/2 keyboard and mouse data, which would be presented to the QL as if from the QL keyboard. A further cog handles the QL sound, and then finally a cog to act as the interface to the QL's ZX8202 chip - using the bizarre bit bang protocol that's on there. It should effectively be a drop in replacement board, but with a small header for programming the prop, and another for the PS/2 connectors.

Because the I/O lines are basically usable how you want, the interface to this chip doesn't have to be the IPC interface, so it could provide all the same functionality to another system with just a rewrite of the interface cog routine. Indeed I plan on talking to it using the 68901 chip's on board uart with a dedicated clock, for a very fast bidirectional serial connection.

There are 8 cogs on the propeller - and I only need 4 to implement sound / ps/2 and ql keyboard scan and talk to the QL. I could emulate the logic of the serial receive routines if a 100% compatible (or even enhanced) interface was desired) With 4 lines required by the propeller to start up, 16 for the keyboard matrix, 4 for ps/2 data and clock and 1 for sound, that leaves 7 lines for talking to the QL or doing other things - for complete 8049 functionality they would all be needed. (rx/tx in, ipl0, ipl1, cts, dtr, comdata, baudx4), although arguably baudx4 isn't needed, as the propeller is very well equipped with counters.



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