Homebrew Sinclair QL ?

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Harry66
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Homebrew Sinclair QL ?

Postby Harry66 » Mon Feb 29, 2016 2:25 pm

Hi.

I was just wondering has anyone made a 'Real' homebrew Sinclair QL from old Legacy ICs MC688008 etc. As I'd like to build my own QL and I don't have a MIST FPGA board. As old QLs die and they get harder to get (Cheap) then this seems like a good way to keep the QL alive.

Thanks


Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Mon Feb 29, 2016 4:20 pm

I haven't tried yet but I am also interested in a home brew QL.
I guess having the hardware description in mist this can be achieved now.
At least regarding original video.
No micro drive or qlnet yet.
kind regards Paul


Harry66
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Re: Homebrew Sinclair QL ?

Postby Harry66 » Tue Mar 01, 2016 10:00 am

I suppose the first thing would be to put down a an achievable specification on paper ! Some thing like :

MC68008P10 CPU (clocked at up-to 10MHz?)
768K SRAM
Various ROM (EEPROM, 27C010 ?)
Two CPLDs to replace the original ULAs
Possible Dual port SRAM as video RAM ?
CF Card (IDE) to connect Hard Drive or compact flash
SD Card ? to replace original micro-drives
Possibly even a V9938 VDP as a second video processor (with Superimpose) to give sprites etc.
SAA1099 Sound Chip (as these are quite powerful and cheap) as the original QL had no sound chip as such
Plus all the original functionality to maintain compatibility.

The VHDL logic for the CPLDs could be copied from the MIST FPGA project (with permission) giving hopefully 100% compatibility with original unit.


Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Tue Mar 01, 2016 2:33 pm

I still have some 68EC020 in my spare parts so I'd prefer to use them in place of 8 BIT wide CPU and RAM.
And I don't see the advantage of adding stuff like sound cards or enhanced video as no program will use these.
QL-SD would be my preferred storage because I have some experience with these having sold lots of these.
I'm not shure if its neccessary to add various ROMs. I prefer having these loadable as with MIST.
I also prefer to have the whole system using 3.3V as this makes it possible to use one FPGA instead of multiple CPLDs.
kind regards Paul


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XorA
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Re: Homebrew Sinclair QL ?

Postby XorA » Tue Mar 01, 2016 6:44 pm

Paul wrote:I still have some 68EC020 in my spare parts so I'd prefer to use them in place of 8 BIT wide CPU and RAM.
And I don't see the advantage of adding stuff like sound cards or enhanced video as no program will use these.
QL-SD would be my preferred storage because I have some experience with these having sold lots of these.
I'm not shure if its neccessary to add various ROMs. I prefer having these loadable as with MIST.
I also prefer to have the whole system using 3.3V as this makes it possible to use one FPGA instead of multiple CPLDs.
kind regards Paul


Basically a MIST with a real CPU, but these days its a design that makes sense.


Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Tue Mar 01, 2016 7:04 pm

XorA wrote:Basically a MIST with a real CPU, but these days its a design that makes sense.

Yes, that is pretty much what it would be.
The advantage of these CPU is that they are very low cost and a very low cost FPGA can be used as well.

I still have 25 of these
CPU.JPG

and I am familiar with the development board that Grant Searle uses for his designs:
http://searle.hostei.com/grant/Multicomp/index.html
miniBoard.jpg
miniBoard.jpg (52.42 KiB) Viewed 1327 times

Its available for 15USD including postage from china.
I have already made a ZX81/ZX80/JupiterACE Clone with this board where it plugs in to reduce work and cost.
BlueAngel.JPG

Kind regards
Paul


Harry66
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Re: Homebrew Sinclair QL ?

Postby Harry66 » Wed Mar 02, 2016 9:49 am

I was thinking of more of an Old School Retro machine staying away from too much 'NEW' FPGA stuff.

A rough spec would be

MC68008P10 just to keep originality (and these are cheap, I can get them for $1.50 each)
512K SRAM RAM +
Dual Port VRAM (IDT7008 etc 64K or even 128K)
MCU (Intel 8049 or similar)
EPM7128SLC to replace ZX8302 to control peripherals
EPM7160SLC to Replace ZX8301 to generate video & Memory map etc (with extra video modes)
an SAA1099 sound chip .. just for future software and these too are very cheap
V9938 as second VDP Genlocked , (Superimposed video) to EPM7160SLC84 , thus giving much improved graphics.

Could add extra functionality: (Old School 80s)
MC68B21 PIA
MC68B28 PIC
MC68B50 ACIA
MC68B54 ACIA
R6522 VIA
R6532 RIOT

Even a AM9511 old School FPU and DS12C887 RTC to update the Real Time Clock

Would need to do a Full feasibility study and costing etc to get an idea of what it's all about !


Mark66
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Re: Homebrew Sinclair QL ?

Postby Mark66 » Wed Mar 02, 2016 10:04 am

Can you put the ZX8301,ZX8302 onto CPLDs?? & How many Macrocells do the ZX8301 & ZX8302 use in order to put them onto CPLDs ?? The EPM7128 has 128 macrocells and the EPM7160 has 160 macrocells available.... is this enough ?


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vanpeebles
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Re: Homebrew Sinclair QL ?

Postby vanpeebles » Wed Mar 02, 2016 10:06 am

Hello, how come you two are both 66? :D


Paul
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Re: Homebrew Sinclair QL ?

Postby Paul » Wed Mar 02, 2016 10:33 am

Harry66 wrote:I was thinking of more of an Old School Retro machine staying away from too much 'NEW' FPGA stuff.
...
EPM7128SLC to replace ZX8302 to control peripherals
EPM7160SLC to Replace ZX8301 to generate video & Memory map etc (with extra video modes)...

I can understand this but the CPLDs are developed with the same software as the FPGA.
And its easier if your code doesn't have to be split up in multiple devices.
You will also need an IO-Processor for your QL.
By the way, do you know a source for those EPM7160SLC?
Cheapest I found was US $15,58 from Ebay/GC_Supermarket. That's more than the FPGA development board which has 5000 Cells in place of 160.
I'm always looking for an affordable source for these EPM7160SLC as these are the largest I know with PLCC casing and 5V compatibility.

Your Idea has the big advantage that its all 5V which makes it possible to add the QL Port for addons...



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