NMS-8220 2+ conversion

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By Caliostro

Expert (74)

Аватар пользователя Caliostro

09-06-2021, 00:10

Hi all, I'm trying to convert a NMS-8220 to 2+, I installed the 9958, pins 1-4-27 together and 21-58 together, but it remains black screen, I inserted carnivore 2 and from the headphone output, I hear music, both with bios 2 and with 2+, I don't understand what could have happened.
P.S. i tried 2 9958

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By gdx

Enlighted (4479)

Аватар пользователя gdx

09-06-2021, 02:00

Did you connect the diode from Z80 (pin 24) to VDP (pin 26)?

By Caliostro

Expert (74)

Аватар пользователя Caliostro

09-06-2021, 08:37

yes, it doesn't work ... ossc says no sync

By Jipe

Paragon (1488)

Аватар пользователя Jipe

09-06-2021, 09:30

check the schematic , on the NMS 8220 the pin 27 is not free but on +5V
cut the wire or remove the pin

By Caliostro

Expert (74)

Аватар пользователя Caliostro

09-06-2021, 09:47

this is the current state:

By Jipe

Paragon (1488)

Аватар пользователя Jipe

09-06-2021, 13:27

By Caliostro

Expert (74)

Аватар пользователя Caliostro

09-06-2021, 15:13

Indeed, without OSSC there was a bad picture, I added the capacitor and everything was fixed, many thanks everyone, now I enjoy my 8220 2+ !!!
P.S. record F4 what is it for? is it indispensable for games?

By Jipe

Paragon (1488)

Аватар пользователя Jipe

09-06-2021, 15:52

F4 Port is for have a hard reset and a soft reset
i know Graphsaurus and Synthesaurus use it
it is not indispensable for games Wink
but required a special subrom without F4 port

By sdsnatcher73

Paragon (1972)

Аватар пользователя sdsnatcher73

09-06-2021, 19:28

MSX will work fine without F4 register. Soft reset on MSX2+ is same as on MSX2 (result is a reset of the machine). The difference is on MSX2+ with F4 register the BIOS can differentiate between a hard reset (power on or reset button) and a soft(ware) reset. With software reset the boot logo is omitted, so you win a little time on a 2+ during a soft reset.

By gdx

Enlighted (4479)

Аватар пользователя gdx

10-06-2021, 10:39

Do you have the 2+ ROMs you need for this model?
F4 port or not, you need a special main-Rom and sub-Rom.

By Caliostro

Expert (74)

Аватар пользователя Caliostro

10-06-2021, 15:51

yes, i used 8235 rom without F4 and kanji rom, everything works fine

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