WTB or trade: external RAM mapper

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By pitpan

Prophet (3152)

pitpan's picture

19-02-2009, 11:51

I'm looking for an external RAM mapper with any size between 1 Mbit and 4 Mbit (128-512 KB) fully compatible with MSX1 models. I need it in order to use MSX-DOS2 in MSX1 computers.

Please send offers to "erobsy" e-mail account in gmail.

I've got also some neat pieces of hardware/software to trade: 4 Mbit MegaRAM, 4 Mbyte external mapper, some Konamis, etc.

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By Jipe

Paragon (1551)

Jipe's picture

19-02-2009, 18:19

i think you don't use MSX-DOS2 with a MSX1

i have the original Cartridge of DOS2 with 256k Ram inside and on Package is just MSX2 symbol

if compatibility with MSX1 symbol MSX required

By Warchild

Paragon (1297)

Warchild's picture

19-02-2009, 19:44

Hi, just now a spanish user is selling a memory mapper, maybe it's what your looking for. You can check the post called " VENTA Memory mapper 512KB / PHILIPS MUSIC MODULE / NEMESIS 3" at spanish forum to see a picture of it. It's no compatible with Turbo-R but I think can be used in all other msx computers... contact the seller (l1nux1n) if you're interested. I think he speaks english too.


By Repair-Bas

Paragon (1153)

Repair-Bas's picture

20-02-2009, 08:05

Dos 2 and a memory mapper do not work on a msx1

By pitpan

Prophet (3152)

pitpan's picture

20-02-2009, 09:17

If it does not work, then I'd like to know how can you explain this ;)

I don't know if it is a patched version included within CF-IDE, but the thing is that it seems to work like a charm.

Thanks for the reminder, Warchild. I'll contact the seller ASAP.

By Jipe

Paragon (1551)

Jipe's picture

20-02-2009, 17:30

i'm testing Ascii Dos2.20 256k mapper with a Canon V20 and external FDD HBD50 or HBK30 -> no work and rest DISK BASIC version 1.00

with Sunrise CF ATA-IDE or Sunrise ATA-IDE and 512k mapper in the same Canon V20 Dos 2.30 work perfectly DISK BASIC version 2.01

sub directory and ramdisk work also

i testing with old Ide interface Sunrise (1996) and don't work

good work of Sunrise

By pitpan

Prophet (3152)

pitpan's picture

20-02-2009, 21:55

Thanks for the test, Jipe.

Still, anyone interested in selling / trading such a thing?

By Manuel

Ascended (18779)

Manuel's picture

13-03-2009, 22:47

Jipe wrote: "i'm testing Ascii Dos2.20 256k mapper"

Could you post some information about that thing? E.g., photos? And photos of the pcb, so that we can see something about the memory mapper?

Is there a ROM dump of this original ASCII DOS 2?

By RetroTechie

Paragon (1563)

RetroTechie's picture

14-03-2009, 04:06

RAM memory mappers work just fine on MSX1. Problem is MSX1 machines don't properly initialize memory mappers, because memory mapper standard didn't exist at the time MSX1 system ROM was written. An MSX2 or above will do the equivalent of this on startup:

OUT (#FF),0
OUT (#FE),1
OUT (#FD),2
OUT (#FC),3

Which switches the first 4 mapper blocks in page 0-3 of the memory mapper slot (this affects all memory mappers simultaneously). This happens very early in the boot process, before RAM is searched or ROM cartridges are started. An MSX1 doesn't have this code in ROM, and therefore you usually have 0's in the mapper registers when you switch the machine on. When the MSX1 does a memory test, that behaves like a single 16K block of RAM, mirrored in pages 0-3.

When you do this initialization manually and reset the MSX1, it's perfectly possible to run software that uses a memory mapper, as long as no MSX2-specific features are used. I know of at least 1 example, and many cracked megaROMs of MSX1 games should also work.

Possibly the same goes for MSX-DOS2, again: as long as the above is observed. Maybe the Sunrise CF interface does some trick to use mapper RAM after the MSX1 has started? I would try myself, but I'm still waiting for a Sunrise CF interface to arrive here (6 weeks and counting, damn it Crazy)

Oh BTW. pitpan: knowing this, why are you looking for a memory mapper, when you've already got a 4 Mbyte external one? Memory mappers differ in size, if they work at turbo speeds and so on, but as for how they work on MSX1, a 4 MB external mapper is as good as any other. What are you hoping to gain?

By Jipe

Paragon (1551)

Jipe's picture

14-03-2009, 11:26

for manuel : first picture for patient rest


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