Newbie - Dewoo CPC-400s. Memory prevents running MSX software

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By RetroTechie

Paragon (1563)

Аватар пользователя RetroTechie

28-12-2015, 20:58

Okay... so the DW64MX1 has 4-bit wide mapper registers (matching its built-in 256K mapper), higher bits are don't cares and read back as "1". The only open question then is if those higher bits are left in high-impedance state so that external mappers may provide read-back for those (probably), or the DW64MX1 'hardwires' them to "1" when mapper registers are read (probably not).
The CPC-300E uses 3 of those bits to make a 128K mapper, but fills only half of that with RAM.

All clear now, Manuel? Smile2

Btw thx for testing that on real hw, adxx! No surprises here, but nice to have confirmation on the exact behavior.

By adxx

Rookie (18)

Аватар пользователя adxx

28-12-2015, 22:07

No problem! Thats a learning process for me as well!
BTW, I checked the available CPC-400 photos of PCB and see that my expectations of 256KB should be no problem to implement - it has M17 from DW64MX1 connected to B input of 74LS139, while in CPC-300 it is connected to GND.

By adxx

Rookie (18)

Аватар пользователя adxx

05-01-2016, 20:15

so far - good news/not so good news.
Good:
- adding 2x 41464 bumps memory to 128KB, BASIC test reports 0-7 now and not as before 0-3, 255
(sorry, no pic yet, this is a temporary ugly PLCC hack while DIP is on its way)
Not good:
- Sunrise IDE-CF shows wierd beaviour - when mashine is powered ON, it shows INIT steps, identifies the CF name correctly, and later just starts with Disk Basic - this is also proved by test in blueMSX with CPC-300E config and the memroy increased up to 128KB

...so far I am stuck with this Sunrise IDE -CF issue.

EDIT: when I feed blueMSX with Nextor rom, it starts with the same style - Nextor Basic. I can _fdisk, it show me info in which slot Sunrise installed, and on the next step it just hangs. On a normal MSX2 profile machine, it runs very smooth no problems.

By adxx

Rookie (18)

Аватар пользователя adxx

09-01-2016, 00:52

Ok, so here is my ugly testing environment Cool

And this final the easy 128KB mod:

Still plenty of room on top of the memory.
Same sort of simplicity woks for CPC-400 for 128KB -> 256KB mod.

Bad news - Sunrise IDE interface does not work with Daewoo. Nextor - also doesn't work.

Any advice for CF or SD interface?

By l_oliveira

Hero (533)

Аватар пользователя l_oliveira

11-01-2016, 17:01

have you tested a "pure" DOS2 kernel on it? Like the ASCII DOS2 cartridge or a clone of it?

I'm saying that because the DOS2 contained on SD card and Sunrise IDE are modified.

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