Idea of RAM expansion cartridge

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By NYYRIKKI

Enlighted (5897)

NYYRIKKI의 아바타

02-03-2020, 22:01

erpirao wrote:

could be used like the old Z380 by Leonardo Padial, it would be very interesting.

Indeed... I believe Leonardo Padial had similar design (using ports #F8-#FB) on his Z380 board...

Eugeny: Does this kind of extension make any sense? ... No, not really... Would I buy it? Not likely...
There are already lots of flash cartridges that have 128MB or more... and you can even change the memory card to them to have yet another 4 partitions full of MSX stuff! ... and 256MB of RAM is about 256 times more than I think I need... If more RAM is required, it starts to feel like design flaw... and most likely causes just too long loading / precalc times.

How ever... I think I understand your hidden point... Big RAM chips are likely more cheap and more easy to get than small chips... and they likely use less electricity etc. etc. -> It most probably feels even more stupid to buy a large chip to be mounted on MSX and then leave 90% of it unused and not mapped to anywhere. When this happens you have to start thinking solutions like this, but unfortunately you can't force people to like these ideas although from hardware point they make total sense...

20+ years ago I would have said "Yes" just because it would have been cool to say "My MSX can support more RAM than your PC", but for that... This kind of extension to the standard is not enough anymore... You should say you support max 128GB of RAM before we could get that feeling again.

By ToriHino

Paladin (741)

ToriHino의 아바타

02-03-2020, 22:14

Quote:

You should say you support max 128GB of RAM before we could get that feeling again

I think i'm not even going to calculate how many 16K segments that would be Tongue oO

By NYYRIKKI

Enlighted (5897)

NYYRIKKI의 아바타

02-03-2020, 23:39

ToriHino wrote:
Quote:

You should say you support max 128GB of RAM before we could get that feeling again

I think i'm not even going to calculate how many 16K segments that would be Tongue oO

Let's put it this way... Filling that amount of memory with 0 on standard MSX (using LDIR) would take more than 10 days. Smile

By spacemoai1973

Master (165)

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03-03-2020, 00:33

erpirao wrote:

I think it may be a good time to recover this z380 project, or implement an advanced z80 cpu in fpga.

You mean like the 萌SX project?

By gdx

Enlighted (5009)

gdx의 아바타

03-03-2020, 02:20

Pencioner wrote:

I can only think if both flash and RAM could be used as a fast ramdisk solution, having two RAMdisks of 128Mb, where 128Mb of data of one disk can be persistent and seeded from flash content on boot (on FPGA level, so no Z80 involved in copying such a huge amount of data), and thus the command to synchronize it back (on FPGA level) to make changes persistent should be implemented.

RAM + Flash does not make sense for a disk of this size. I would prefer a smaller disk with SRAM only. There are SRAMs that keep their data for a very long time. And adding RAM would allow this Sramdisk to be used on any MSX. 4Mo SRAM + 8Mo RAM (one chip) would be perfect.

By DarkSchneider

Paladin (942)

DarkSchneider의 아바타

03-03-2020, 09:27

Quote:

Flash memory will be controlled through EXTBIO mechanism.

I plan to use one additional I/O port for configuring the device (e.g. port 5D - I see this port is assigned to MSXPi interface, but the project website seems to be broken).

The API must be loaded externally (be built into the application or be loaded as a driver).

That's a nice point for doing things.

About the expansion, I think is (more than) excesive. On MSX 256KB or 512KB as much is all you need for doing anything. Think that you manage the memory handling 16KB segments, so too many of them you reach a point that they are unncessary.

By erpirao

Paragon (1236)

erpirao의 아바타

03-03-2020, 10:24

spacemoai1973 wrote:
erpirao wrote:

I think it may be a good time to recover this z380 project, or implement an advanced z80 cpu in fpga.

You mean like the 萌SX project?

no, the the 萌SX i s a completely new system, and I talk about this: lpe z380

or to use a fpga with the [b]nextz80[/b], y80e or modified kernels, in fact eugeny has already made a matchpack for the gr8net, so it has advanced work.

By spacemoai1973

Master (165)

spacemoai1973의 아바타

04-03-2020, 01:50

The Z380 CPU has several annoying bugs though. They were fixed in the Z382 MPU, but ZiLOG never released a fixed Z380. Besides the maximum clockspeed is quite low (max. 18MHz), because ZiLOG never released the promised 40MHz version either. Even at 18MHz, you need really fast RAM (50ns) so effectively 14MHz is the maximum. At that clock it's similar in speed to a 7MHz R800.

Besides, LPE-Z380 was part of a "completely new system" too, the E-MSX. The LPE-EV4 32bit slotexpander was its motherboard. It had DMA controllers available as well. As you can see there's an adapter from 60 pin to 50 pin slots, because LPE-EV4 had 60 pin slots. To use MSX cartridges, you had to remove the cartridge shell and use pieces of paper to prevent you from inserting the cartridges wrong.

By JunSoft

Resident (42)

JunSoft의 아바타

04-03-2020, 07:08

Quote:

The Z380 CPU has several annoying bugs though.

Interesting. Where can I find the bug report?

By gdx

Enlighted (5009)

gdx의 아바타

04-03-2020, 12:35

Why always bring out the Z380? There are many other Z80 compatible ones like the Z8400, Z84015, eZ80, KL5C8400, etc. There are some which are fast and consume very little.

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