DIY 2MB and 4MB memory mapper

DIY 2MB and 4MB memory mapper

by HansO on 06-09-2018, 20:25
Topic: Hardware

Andrey Koryakin has designed an internal memory mapper of 2M and 4MB for MSX2 and MSX2+ computers with a real physical Z80 chip. The processor has to be moved from the mainboard to the memory mapper PCB. After that this complete PCB will be put back to the place where the Z80 came from.

Memory registers and back annotation are supported.

This PCB has been tested on Sony HB-F1XD, HB-F1XD MK2, HB-F1XDJ, HB-F1XV, Panasonic FS-A1 MK2 and FS-A1F.
It should work on any MSX2 or MSX2+ where a physical Z80 IC is used as CPU.

You can find the full article on the MSX Info Pages with a circuit diagram, an Eagle PCB design and many images. Also note the other regular updates on this page.

Relevant link: Internal memory mapper

Comments (6)

By gdx

Prophet (2213)

gdx's picture

09-09-2018, 11:48

On the linked page, the start screen displays 2048KB. Why are internal 64K ignored?

By Giangiacomo Zaffini 2

Expert (67)

Giangiacomo Zaffini 2's picture

09-09-2018, 13:15

Pretty lovely. And impressive.
A question: - would It work with a MSX-DOS2 rom or NEXTOR rom on a plain old MSX 1?

By gdx

Prophet (2213)

gdx's picture

09-09-2018, 14:01

Giangiacomo Zaffini 2 wrote:

would It work with a MSX-DOS2 rom or NEXTOR rom on a plain old MSX 1?

Theoretically, yes. If the MSX hardware supports this extension and if there is room around the CPU and if the MSX has a free signal /SLTSL, it should work with NEXTOR. MSX-DOS2 requires a patch to work on MSX1. Without Nextor the main Rom requires a patch to put the pages of Memory Mapper in order at start.

By lintweaker

Expert (66)

lintweaker's picture

09-09-2018, 15:27

Nice! Neat 'trick' using the 74373 for back annotation!

By kansaizine

Supporter (13)

kansaizine's picture

10-09-2018, 09:12

It seems that the built-in 64 KB RAM is removed.

By Meits

Scribe (5068)

Meits's picture

10-09-2018, 10:52

Is it removed or is the new mapper put in the same slot?

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