Does S-1990 really support debug functions?
Where documentation explaining this feature can be found?
(even if only for tR it can be really useful for developers)

The answer to that must be in the s-1990 documentation, but where is this document?

Quote:

The answer to that must be in the s-1990 documentation, but where is this document?

The only documents with some information on the Toshiba S1990 are the turbo R ST and GT manuals.

I'm not very expert in Japanese but I feel these manuals do not explain how to access debug features...
Does a "MSX Turbo R Technical handbook" exist? If so is there a japanese user who can sell/send/translate one for European users?

Did you see this info ?
http://map.tni.nl/resources/msx_io_ports.php#s1990

BTW, in reaction to this newspost flyguille said "i got the official documentation of the s1990"

Some more info comes from here:


Debug function

* Memory address comparator: When the address bus of the R800 is
watched and a designated address is accessed, an NMI is generated. The function is enabled when
address bus line A8 is pulled low while resetting the S-1990.

* NMI-status register: When the above-mentioned address
comparator is triggered this register contains the source of the NMI.

* Debug monitor for the cartridge slot register: When the
above-mentioned address comparator is triggered, while operating
the debug monitor, this control register controls the slot environment.

* NMI-return address register: contains the return address to the user
program, so it can return to the original program after exiting the debugger.

* Breakpoints: When debug mode is enabled, pressing the pause key
breaks the user program and jumps to a debugging Monitor in ROM.

Well, If flyguille and/or k0ga have this documentation, I think they will do a really great gift to MSX community if they share these infos

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Memory address comparator: When the address bus of the R800 is watched and a designated address is accessed, an NMI is generated. ...bla bla bla... Breakpoints: When debug mode is enabled, pressing the pause key breaks the user program and jumps to a debugging Monitor in ROM.

If an NMI is generated, shouldn't there be some code to handle it in the TurboR BIOS ROM? Is this debugging Monitor ROM part of the ROM in a Turbo R?

I recall some magazine stating that the NMI line isn't connected in MSX. Does this hold for turboR as well then? Otherwise, that debug function doesn't make sense, really...

Yes i remember i asked this in a thread some months ago,the nmi is not connected by default so on msx1/2 machines we do not have nmi interrupts -on zx spectrum this is different i think and works-.There is way though to connect it but requires soldering skills.

@ D-Tail & nikodr: looking at GT and ST manuals, debug feature seems possible on turboR machines.

@ sjoerd: turboR's BIOS can be mirrored in ram (as GFX9000's powerbasic) and adapted to handle a "restart" to 0x66.
Probably in DOS mode NMI would "fall" in a fcb or similar... but I think that wouldn't be an unsolvable problem.

The real issue is to find documentation... (also in japanese would probably be useful).

I mean: You may be able to find some information by looking at the turboR roms. msx bios has an nmi handler and an nmi hook.

But some s1990 (and r800) documentation would be nice.

@ sjoerd: in turboR's bios at 0x0066 there if a jp to a call to nmi's hook which terminates with no action... so no hints.

I succeded in contacting flyguille but he admits he confused the document with another pdf and later he rectified his assertion... so no documentation atm...

This statements seems to have been copied from the Wikipedia's article about the S-1990:


http://en.wikipedia.org/wiki/S-1990


The wikipedia English article by itself seems to be a babelfish translation of the Japanese article:


http://ja.wikipedia.org/wiki/S1990


The debug part of the Japanese article was written by some user called "Baz1521". Maybe someone can locate this guy and ask him for some documentation.

Quote:

Some more info comes from here: Debug function * Memory address comparator: When the address bus of the R800 is watched and a designated address is accessed, an NMI is generated. The function is enabled when address bus line A8 is pulled low while resetting the S-1990. * NMI-status register: When the above-mentioned address comparator is triggered this register contains the source of the NMI. * Debug monitor for the cartridge slot register: When the above-mentioned address comparator is triggered, while operating the debug monitor, this control register controls the slot environment. * NMI-return address register: contains the return address to the user program, so it can return to the original program after exiting the debugger. * Breakpoints: When debug mode is enabled, pressing the pause key breaks the user program and jumps to a debugging Monitor in ROM.