Slot Expander

By blackmsx

Expert (74)

blackmsx's picture

11-10-2018, 11:01

Hello everyone!

I've build a slot expander following this schematic:

Unfortunately, only the first subslot accept ROM cartridges (like games carts or IDE/floppy interface with ROM). The rest of the slots work only as a I/O slot (OPL4 cart works).

Is this the intended function or do I have something wrong going on in my circuit?

I havent connected the BUSDIR/INT filter as is explained in PTC-PRINT nr 26. It is supposed to work without these filters?

Thanks in advance for the help!

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By Wild_Penguin

Champion (479)

Wild_Penguin's picture

11-10-2018, 15:55

Well, it clearly has a subslot register and decoder chips, sot it definitely should work with ROMs.

Otherwise, I'm no expert and have little experience with slot expanders. Perhaps (I'm just guessing here) ROM cartridges you tried were those kind that need to be booted up (ROM games, HDD/floppy interface etc.)? It might be that carts can only boot from a primary slot. If you need something more advanced, you need to have an OS or some software which will look for the ROMs and use them accordingly. I could be way off here, though!

Did you try to run slotmap.bas or something similar?

EDIT: I meant slot.bas, or msxmem2, or this utility: http://www.tiny-yarou.com/slotchecker.html . Also see this thread

EDIT2: Or: https://www.msx.org/forum/msx-talk/software/msxmem2

By Wolverine_nl

Paladin (939)

Wolverine_nl's picture

11-10-2018, 15:57

Most cartridges like Megaflashrom SCC+SD, GR8NET, Carnivore2 etc. can only work from a primary slot, so one of your basic physical MSX slots. There are also some games that only work in a primary slot. So it could be a coincidence.

By Jipe

Paragon (1319)

Jipe's picture

11-10-2018, 16:42

see this schéma
slot X4

By blackmsx

Expert (74)

blackmsx's picture

12-10-2018, 11:47

Thanks guys for all the answers.

The cartridges I tried (and did not work on subslots 2,3 and 4) were Konami Tennis, Choplifter, a Sunrise IDE compatible IF (with Nextor ROM) and a TDC600 clone...Im aware that carts that already implement expanded slots by themselves (Carnivore, MFR, etc) will only work on the main MSX slot.

I will try these utilities to see whats going on there, and of course I will check my circuit for any errors...

@Jipe, actually that schematic was my first attempt to build an expander some months ago but I could not get it to work. I might give it a try again. The 74ls352 could be replaced with a 74ls153 and then leave out the 74ls00 at the output, right?

By Jipe

Paragon (1319)

Jipe's picture

12-10-2018, 13:46

the big post for this slot expander is here ( in french )
see the L-olivera remarq at the end

http://msxvillage.fr/forum/topic.php?id=881&pt=1

By blackmsx

Expert (74)

blackmsx's picture

12-10-2018, 14:18

blackmsx wrote:

Thanks guys for all the answers.

The cartridges I tried (and did not work on subslots 2,3 and 4) were Konami Tennis, Choplifter, a Sunrise IDE compatible IF (with Nextor ROM) and a TDC600 clone...Im aware that carts that already implement expanded slots by themselves (Carnivore, MFR, etc) will only work on the main MSX slot.

I will try these utilities to see whats going on there, and of course I will check my circuit for any errors...

@Jipe, actually that schematic was my first attempt to build an expander some months ago but I could not get it to work. I might give it a try again. The 74ls352 could be replaced with a 74ls153 and then leave out the 74ls00 at the output, right?

Thanks!

Its not clear to me which of the two designs cannot use RAM/ROM on page 4, yours or the one I posted here?

In short, is the 74xx02 needed between the main slot and the 74xx139?

I'll investigate further

By Danjovic

Rookie (29)

Danjovic's picture

12-10-2018, 21:17

You can do it without the lS02 as shown in second diagram at msxpro page:
http://www.msxpro.com/slotexp.html

By blackmsx

Expert (74)

blackmsx's picture

13-10-2018, 11:29

Thanks, I think I got it working finally! The problem was the schematic I was working with misses the connection between LS138 pin 6 and VCC, so the pin was floating.

Still is a bit inestable. Sometimes carts are not detected, but when detected it works perfectly. Im using a 30cm ribbon cable, is that too long?

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