Search found 74 matches

by Smonson
Tue Jan 16, 2018 7:57 am
Forum: Chat forum [ENG]
Topic: Surviving STs
Replies: 32
Views: 2167

Re: Surviving STs

If you want an old computer from ebay, but don't like to pay high prices, my favourite technique is to buy several totally broken ones and assemble all the good parts together into one working computer.
by Smonson
Mon Jan 15, 2018 8:22 am
Forum: Chat forum [ENG]
Topic: Very first computer
Replies: 54
Views: 3551

Re: Very first computer

Microbee by Applied Technology Pty Ltd c. 1982, as made famous by Hackerman

Image

My dad built it from a kit!
by Smonson
Fri Jan 12, 2018 2:33 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

I see :) You'll soon learn that the more internal RAM available you have, the more useful SignalTap is. I realize it is not easy to replace the FPGA, but it is recommended to debug with a larger FPGA so that you have lots of internal RAM. Altera provides what they call "Vertical Migration"...
by Smonson
Fri Jan 12, 2018 11:19 am
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

ijor wrote:I guess you know that the FPGA has some sort of integrated LA (SignalTap) that is invaluable for debugging.


Haha, Quartus has about three trillion buttons I've never clicked on... :wink:
by Smonson
Fri Jan 12, 2018 8:25 am
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

I didn't, because of a lack of free time, but I have fixed a couple of bugs since last progress post. Spectrum 512 works well now and also an overscan test program that Troed sent to me that displays a static image with all borders extended. Static test programs like that are useful because I use a ...
by Smonson
Thu Jan 11, 2018 9:55 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Regarding that, it's also a possibility to do so, but I initially envisaged this method being simpler. I think that I was wrong about that, and so I might try to make a board that reads the RGB values from the shifter's pins and leaves the shifter in place (this will work better on STE too). But rig...
by Smonson
Sat Jan 06, 2018 12:27 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Hi Olivier,

It should be possible to perform the same job on the TT, but not with the same hardware. The FPGA board I'm using doesn't have enough IO pins for the 64-bit data bus. But in the future, who knows.

Simon
by Smonson
Thu Dec 28, 2017 2:04 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Yeah, I can sychronise the line timing to either a long gap between DEs (only for standard modes) or VSYNC. Right now I haven't connected HSYNC.

I don't know what you want me to do, things that should be working aren't working, more study is needed, and will be resumed when I have time.
by Smonson
Thu Dec 28, 2017 8:29 am
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Thanks for the summary Troed - you are spot on.

Eventually this stuff will be all be worked out. If someone is impatient and just wants to run standard ST modes, I can sell you a board that can do that right now.
by Smonson
Thu Dec 28, 2017 8:22 am
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Forget about the original clock mux implementation. Forget about the complicated logic of the pixel counter. Your old, simple, shifter model that you said you implemented before, should work. There is nothing special at all about (classic) overscan or sync scroll regarding Shifter. The only thing i...
by Smonson
Thu Dec 28, 2017 12:08 am
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Again, not at all. Both overscan and regular sync scrolling can work just fine with a very simple Shifter model. As Troed just said, they depend mostly on GLUE implementation, not on SHIFTER. The only techniques that require a very accurate SHIFTER model are 4 pixel sync scroll (just a couple of de...
by Smonson
Wed Dec 27, 2017 2:06 pm
Forum: Hardware
Topic: STFM to DVI/HDMI project
Replies: 78
Views: 6262

Re: STFM to DVI/HDMI project

Hi guys, I ran out of time to continue working on it while trying to support overscan and sync scrolling. I'll get back to it in the coming year. If worst comes to worst, I'll forget about supporting those. The problem is these modes and techniques depend on completely internal implementation detail...
by Smonson
Sun Dec 10, 2017 1:22 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: SHIFTER reimplementation on FPGA

I don't know, I'll see if I can find a copy online
by Smonson
Sat Dec 09, 2017 8:03 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: SHIFTER reimplementation on FPGA

Thanks for the extra info Troed. As far as I can tell the register behavior clearing/not clearing should be working. I think the problem is when you're doing register writes mid-scanline, it's triggering reset because LOAD and CS are asserted together. I don't think this is really happening but the ...
by Smonson
Sat Dec 09, 2017 7:58 am
Forum: Coding
Topic: ST Chipset decap
Replies: 125
Views: 25194

Re: ST Chipset decap

Thanks Ijor!
by Smonson
Fri Dec 08, 2017 4:17 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: ST Chipset decap

What information exactly are you missing? Note that Closure is a very special case. You don't need to do anything special to support overscan. Overscan is mostly a GLUE thing. Did you try other overscan software? Most overscan software should work with a Shifter simple implementation. No way to kno...
by Smonson
Thu Dec 07, 2017 11:45 pm
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: ST Chipset decap

FPGA's really don't like this type of clock multiplexor. I would recommend that if you HAVE to use a clock mux then use a macro so you can replace the underlying logic with a primitive which is technology dependant. e.g. For Xilinx you could use a BUFGMUX_CTRL perhaps I'm using a Cyclone-II. Thanks...
by Smonson
Thu Dec 07, 2017 11:25 pm
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: ST Chipset decap

I forgot to mention it but I also clear all the registers at the start of each DE, so each line begins fresh on the first LOAD after DE. That's still how you do it? Or that was only on the original, simple, implementation? Because resetting the line logic unconditionally like that will break Closur...
by Smonson
Thu Dec 07, 2017 4:31 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: ST Chipset decap

It just sycnhronises scanlines to DE, and loads RR from IR every 4th LOAD. Depending the exact meaning of the above sentence, I'm not sure that's the best way. It might be better to synchronize to the first LOAD pulse as the real Shifter does. If you follow DE you might get into some wakeup issues....
by Smonson
Thu Dec 07, 2017 3:15 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

Re: ST Chipset decap

I thought you were taking the digital outputs from Shifter, but I guess you want to replace Shifter altogether, that's nice :) Right now I'm replacing the shifter, because I need the 32MHz shifter clock, and at the time when I started this I didn't realise that most shifters are soldered in place. ...
by Smonson
Thu Dec 07, 2017 1:12 am
Forum: Coding
Topic: SHIFTER reimplementation on FPGA
Replies: 16
Views: 1271

SHIFTER reimplementation on FPGA

Thanks again Ijor :cheers:. My verilog implementation isn't able to run {Closure} properly still, so I'm trying to work out what is different from the real IC. That explanation is excellent, I should have re-read the whole thread before posting. I think I have everything working exactly like your di...
by Smonson
Wed Dec 06, 2017 11:08 pm
Forum: Coding
Topic: ST Chipset decap
Replies: 125
Views: 25194

Re: ST Chipset decap

Where does pixCtrLoad go?
by Smonson
Fri Dec 01, 2017 12:23 pm
Forum: Coding
Topic: ST Chipset decap
Replies: 125
Views: 25194

Re: ST Chipset decap

Both SHIFTER and MMU do have hardware reset even when lacking a dedicated reset pin. They internally generate a reset when the external signals are at a specific invalid condition that would be produced only at reset. In the case of SHIFTER, it resets when both LOAD and CS are asserted. Excellent, ...
by Smonson
Thu Nov 30, 2017 10:14 am
Forum: Coding
Topic: ST Chipset decap
Replies: 125
Views: 25194

Re: ST Chipset decap

Thankyou Ijor for this incredible work. I apologise if this is a silly question, but what is nReset connected to on an STFM shifter which has no hardware reset? Always high, right? Otherwise the LOAD shift register will constantly be cleared. I'm attempting to understand the reload logic but it's a ...

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