Re: MSX2 Compatible Computer Project [message #6529 is a reply to message #6527] |
Tue, 10 September 2019 17:16 |
jdgabbard
Messages: 76 Registered: March 2016
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Sergey wrote on Tue, 10 September 2019 16:38Hi Doug,
Nice case... I've initially 3D printed case for my own Harlequin build. It took more than 24 hours if I recall correctly. Unfortunately in my case I had some wrapping on the edges, and it didn't look too good. So eventually I've purchased an injection molded case with the membrane keyboard.
I bet the mechanical keyboard feels nicer and works better than my membrane keyboard
The mainboard size is 150 mm x 330 mm. Perhaps it could be printed in two halves.
Thanks,
Sergey
Sergey,
I followed your build when you did the Harlequin. And saw that you had printed a case, but I don't remember you mentioning the warping. It is a real problem when using abs. This case was printed in PLA. So warping wasn't an issue. However, I do need to finish a bed upgrade on my bed. I started a MK2 upgrade on my Da Vinci Pro. But the supports I printed are not holding up to the bed temp I'd like to maintain. So once that is fixed I plan on trying with ABS.
As for the bed size vs case size, it sounds doable. It'll be a tight fit in halves, but I guess about 150x175 print size would be a ballpark estimate. The case should be fairly easy depending on layout. I'll have to wait until you have boards ready before I could really start drawing anything up. So I'll wait on you to verify it before committing, since you may need to make some changes to layout.
As for the Harlequin keys, they're great! But I don't have any real reference for the speccy, only the ZX81 (more precisely the TS1000). Touch typing is a bit awkward due to the layout of the keyboard. But it's not too terrible. I plan on a slight redesign adding holes for a reset switch and a bank switch for the ROM's A14 line. But other than that, I've very happy with it. I can share the STLs if you're interested. But I'll stop there, as I'm getting pretty far off topic of the thread, and it's only meant as a reference to the fact I enjoy creating things like that.
Doug Gabbard
Creator of the G80-S Micro Computer and 'Porter' of TinyBASIC 2.5g
Website: http://retrodepot.net
z80 TinyBASIC 2.5g: http://retrodepot.net/?p=424
AtariAge Username: jdgabbard
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Re: MSX2 Compatible Computer Project [message #6571 is a reply to message #6529] |
Thu, 26 September 2019 09:32 |
Sergey
Messages: 236 Registered: October 2015 Location: Portland, OR
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Hi,
Here is the project status update:
- I've received the PCBs.
- I've compiled a preliminary Bill of Materials
- I've soldered most of the components, or in case of ICs - sockets, that are required for minimal test configuration.
- I am waiting for some components from Mouser, as it turned out I haven't ordered everything I need for this project just yet
- The next steps are to complete that minimal configuration - VDP, Z80, memory, PPI, slot/paging logic, SPLDs, timing logic, keyboard, and test and debug that configuration.
- Once it is working, I'll gradually add other components: Video circuitry, PSG, slots' buffers, printer control, cassette tape recorder support, and so on.
- So far I've found a few issues, all related to the silkscreen, they are documented in Known Issues section.
Here is the photo of the board so far:
Cheers,
Sergey
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Re: MSX2 Compatible Computer Project [message #6602 is a reply to message #6601] |
Tue, 01 October 2019 11:30 |
Sergey
Messages: 236 Registered: October 2015 Location: Portland, OR
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Yes, the slot enumeration seems to work. It worked before too. It just there is an EI at the end of the slot enumeration.
Frankly, I am not quite sure why check_expanded subroutine in C-BIOS has an DI/EI around it.
The interrupts are disabled anyway at reset. The first instruction of C-BIOS is DI. And they get enabled later on.
And check_expanded is only called during the initialization. They could have saved two bytes on these DI/EI!
I'll connect a pull-up to VDP later today, and will continue working on debugging the board.
On an unrelated note, I am wondering how useful the printer port is... Perhaps I should replace it with a WD37C65 FDC?
[Updated on: Tue, 01 October 2019 11:32] Report message to a moderator
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Re: MSX2 Compatible Computer Project [message #6612 is a reply to message #6608] |
Tue, 01 October 2019 19:57 |
Sergey
Messages: 236 Registered: October 2015 Location: Portland, OR
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Good news are that after connecting a pull-up to VDP /INT the system no longer getting stuck at EI.
In fact according to my POST display it boots all the way and gets stuck not finding any ROMs to boot from.
The not so good news are that I still don't have any display.
Nothing on V9938 VDP RGB and VIDEO pins. There's ~127 kHz signal on CSYNC and HSYNC instead of expected ~14.59 kHz. Also the /INT frequency is about 250 Hz instead of expected 60 Hz.
I am wondering if C-BIOS doesn't initialize VDP correctly (e.g. skips initializing some essential registers)?
I've checked the VDP wiring, compared it to other designs and I haven't find any issues. I also checked that chip select is generated, and in fact I can even see VDP writing to VRAM, apparently when BIOS is clearing the screen.
[Updated on: Wed, 02 October 2019 11:21] Report message to a moderator
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Re: MSX2 Compatible Computer Project [message #6622 is a reply to message #6621] |
Fri, 04 October 2019 08:05 |
lintweaker
Messages: 69 Registered: April 2018
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Sergey wrote on Fri, 04 October 2019 15:41
Jurgen:
My CSYNC level shifter works just fine. I assume it will also work with V9958, although in this case it is possible to bypass it. I am wondering if you're outputting the sync signal(s). And if so, what signals and voltage levels (e.g. VGA needs both VSYNC and HSYNC in TTL levels, SCART uses composite sync at 0.7V or so level, but apparently it can get sync from composite video too)
I am not using a 'real' VGA output. I do not have a VGA monitor that still works with a 15kHz signal, although I use a VGA connector for output with RGB and COMP as sync signal. I can switch COMP between composite video and VDP csync.
With the VGA connector I am using a VGA-to-SCART cable which has an additional USB connector for the switch signal. This then goes to a cheap SCART to HDMI converter. An other option is a VGA 'scan doubler'.
[Updated on: Fri, 04 October 2019 08:09] Report message to a moderator
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Re: MSX2 Compatible Computer Project [message #6741 is a reply to message #6740] |
Sat, 09 November 2019 16:04 |
Sergey
Messages: 236 Registered: October 2015 Location: Portland, OR
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Quote:what obstacle is there for you for providing a generic compatible MSX2+ bios?
I don't really feel like getting into a legal hurdle with Microsoft and whoever owns the MSX stuff now. So I don't plan to distribute MSX2 BIOS or BASIC. The open source alternative (C-BIOS) is available. Also there are plenty of places on the internet one can get MSX2 ROMs. I plan to provide a script to create the ROM image using either one of these options.
Quote:Given that the owner of the MSX standard has agreed that it's all freely available
In an interview to someone? There is no official statement. There's no place where MSX binaries or source code had been officially released.
Quote:you owe a $1 debt to Microsoft for using MSX basic
Where do I put that dollar? But seriously. I personally don't feel like I owe anything for using 30+ old piece of software for recreational and non profit purposes, that hasn't been a money maker for the company for at least 25 last years. Yet, it is quite possible that some patent troll representing MSX will go after me, just because there is "MSX" string somewhere in the binaries.
[Updated on: Sat, 09 November 2019 16:37] Report message to a moderator
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Re: MSX2 Compatible Computer Project [message #6746 is a reply to message #6741] |
Sun, 10 November 2019 00:49 |
bifo
Messages: 48 Registered: October 2019
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Quote:Quote:Given that the owner of the MSX standard has agreed that it's all freely available
In an interview to someone? There is no official statement. There's no place where MSX binaries or source code had been officially released.
Given that this project is 'build-your-own' and in theory teaches people how the various parts work with each other, you should drop a line to the man who did the interview and try to get in touch with Nishi-san himself. I think this project would tickle his fancy.
Frankly, we should let him know about all of what retrobrew does, I think he'd appreciate the existence of a place like this, a community of old school hackers.
[Updated on: Sun, 10 November 2019 00:52] Report message to a moderator
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