NMS8245 2+ upgrade

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By Philip

Champion (366)

Philip's picture

11-09-2018, 12:02

Angelo Sanna wrote:
Philip wrote:

That's very nice actually, because I'm making a automatic detection of the presence of the F4 register.
You can test it for me Smile

No problem Smile

Thanks!

Angelo Sanna wrote:
Philip wrote:

What do you get if you type this after powering on the 8250?
?INP(&HF4). Because there are normal and inverted implementations of the f4 register apparently...

255.

It seems you need the regular rom, not the inverted f4 version (see below)

NYYRIKKI wrote:

Personally I replaced F4-port with RETURN-key. -> If return is not pressed the logo is displayed and if return is pressed, then the logo is skipped. This kind of works since many times when you execute some command to perform soft reset, you apply the command with RETURN-key anyway...

Nice idea, I took the liberty to steal this feature as well.

So the new features in these roms are the f4 detection and if it is not found the f4 emulation with the RETURN key.

https://msx.vanderhoeven.org/systemroms/nms8245_2p.zip
https://msx.vanderhoeven.org/systemroms/nms8250_2p.zip

Also included are version for an inverted f4 port. Just to be clear (hopefully :) ), in the 8245 version the inverted rom replaces the normal rom, not the extra rom.

By Angelo Sanna

Supporter (14)

Angelo Sanna's picture

11-09-2018, 22:54

Yes, will check this out Philip, many thanks! Smile

** edited message, not needed to quote you again. **

By Angelo Sanna

Supporter (14)

Angelo Sanna's picture

20-09-2018, 21:50

Have finally get new EPROMS 27Cxxx's to burn the system software. So I think this would be in a few days. I keep you informed. Smile

By Angelo Sanna

Supporter (14)

Angelo Sanna's picture

29-09-2018, 03:02

Philip wrote:

Nice idea, I took the liberty to steal this feature as well.

So the new features in these roms are the f4 detection and if it is not found the f4 emulation with the RETURN key.

https://msx.vanderhoeven.org/systemroms/nms8250_2p.zip

Also included are version for an inverted f4 port. Just to be clear (hopefully :) ), in the 8245 version the inverted rom replaces the normal rom, not the extra rom.

Hey Philip, just testing right now. I have burn the NMS 8250 EPROMS. I have tested the normal version, the inverted version not yet. But It is working. I have desolder the F4 latch IC's from the motherboard (74LS173 & 74LS02) and the 8250 is booting with 2+ logo. In basic I have also used the command: ?INP(&HF4) and also a return with 255.

If I type: DEF USR=0 (and then) A=USR(0), a cold boot appears. Normally with the orginal F4 latch and the ROMS I used before I get a warm boot without MSX boot logo. But I have understand this "warm" boot is not important and not many programs use this warm boot, right? Can you or someone else confirm this? Thnx!

So, because it is working I guess the version with inverted F4 is not needed to test? Can you also confirm this? :)

By Angelo Sanna

Supporter (14)

Angelo Sanna's picture

29-09-2018, 03:21

Oh yes, another question @Philip, it is about the diskROM, I see other behaviour. The led of the diskdrive flashes twice, and the third time to read a disk. What version of diskROM is this? Is it an edited version? Or is it the 1.8 Philips fast diskROM? Can you tell more about this version? Normally the led of the drive flashes once, and then for the second time to read the disk.

I have also a question about the c-sync signal, but I have read here there is a solution for the NMS8245 with the V9958. Because on a new LCD scart monitor the screen is not stable. On CRT it is stable as rock. I have experimented with an LM1881N c-sync IC but it is not an solution.

I guess it is something with the +5Volt powerline from the powersupply in the 8245. So I do some more research, and will test it soon with an 7805 with directly powerlines to the V9958 with some 100nF capacitors on the 7805. It is like the schematic of Hans Oranje for the 8280, also with a seperate powerline to the V9958 with an 7805.

And of course if it is not the solution, I will test it with the resistor and parallel an capacitor on pin 6 (csync output on the V9958), because I have read more people here got this problem. The c-sync signal is not clear. But this must be have a reason. So I think this is because the power supply in the 8245 is not clean enough. And yes, I have already replaced the capacitors in the power supply and tested it on low ESR. Maybe you or someone else who is reading here have an opinion about this. Let me know. Smile

By Philip

Champion (366)

Philip's picture

30-09-2018, 21:20

Quote:

Hey Philip, just testing right now. I have burn the NMS 8250 EPROMS. I have tested the normal version, the inverted version not yet. But It is working. I have desolder the F4 latch IC's from the motherboard (74LS173 & 74LS02) and the 8250 is booting with 2+ logo. In basic I have also used the command: ?INP(&HF4) and also a return with 255.

If I type: DEF USR=0 (and then) A=USR(0), a cold boot appears. Normally with the orginal F4 latch and the ROMS I used before I get a warm boot without MSX boot logo. But I have understand this "warm" boot is not important and not many programs use this warm boot, right? Can you or someone else confirm this? Thnx!

So, because it is working I guess the version with inverted F4 is not needed to test? Can you also confirm this? Smile

Thanks for testing! Good to hear it actually works Smile
The warm boot is not used a lot indeed. Synth Saurus 2 is one of them. But it should still work with the return-f4-emulation.

There is no point in testing the inverted F4 version as the only difference is that it inverses the F4 bit before writing and after reading it.

By Philip

Champion (366)

Philip's picture

30-09-2018, 21:35

Angelo Sanna wrote:

Oh yes, another question @Philip, it is about the diskROM, I see other behaviour. The led of the diskdrive flashes twice, and the third time to read a disk. What version of diskROM is this? Is it an edited version? Or is it the 1.8 Philips fast diskROM? Can you tell more about this version? Normally the led of the drive flashes once, and then for the second time to read the disk.

The diskrom is indeed the 1.8 Philips fast diskrom. It is not altered. Can you test the new roms with your old diskrom?

Angelo Sanna wrote:

I have also a question about the c-sync signal, but I have read here there is a solution for the NMS8245 with the V9958. Because on a new LCD scart monitor the screen is not stable. On CRT it is stable as rock. I have experimented with an LM1881N c-sync IC but it is not an solution.

I guess it is something with the +5Volt powerline from the powersupply in the 8245. So I do some more research, and will test it soon with an 7805 with directly powerlines to the V9958 with some 100nF capacitors on the 7805. It is like the schematic of Hans Oranje for the 8280, also with a seperate powerline to the V9958 with an 7805.

And of course if it is not the solution, I will test it with the resistor and parallel an capacitor on pin 6 (csync output on the V9958), because I have read more people here got this problem. The c-sync signal is not clear. But this must be have a reason. So I think this is because the power supply in the 8245 is not clean enough. And yes, I have already replaced the capacitors in the power supply and tested it on low ESR. Maybe you or someone else who is reading here have an opinion about this. Let me know. Smile

On my 8250 converted to 2+ (but it was the same before converting it) the screen is slightly wobbly. I thought I fixed this by replacing all of the capacitors. But then I found it only wobbles when there is a monitor on top of it. It doesn't matter if it a crt of a lcd.

The screen on my 8245 is rock solid on both crt and lcd. The only thing is the diskdrive that disturbs the screen. So I fixed that by replacing it with a gotek Smile

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