ZX-MMC2 ("the ZXPand") Update log

[sirmorris]

... I wonder wether there would be a way to have the 32K RAM in ZXPand "surrounding" the internal memory by enhancing CONFIG M for TS1500 knowing how it reacts on RAMCS pulled high instead of changing TS1500s behaviour?

It may be possible.

I assume there is no way for ZXPAND to detect if it is attached to a TS1500.

Correct.

For example from 8k-32K, followed by 16 internal ram, followed by the remaining 8K of ZXPand from 48K-56K by entering CONFIG "M=8" and from 16k-32K, followed by 16 internal ram, followed by the remaining 16K of ZXPand from 48K-64K by entering CONFIG "M=4"?

That would require at least 2 extra inputs to the GAL for the different modes. There is physically only 1 unused input. This is connected to the jumper block beneath the sd socket.

It might be possible to have a 'TS' versus 'ZX' mode, however the equations are pretty tightly packed at the moment, there probably isn't space.

I can open up the equations and those who have GAL experience can critique them.

I'll start a new thread.

C

[Prime]

I assume there is no way for ZXPAND to detect if it is attached to a TS1500.

Correct.

Would it not be possible to attach one of the unused outputs oon the PIC (if there are any), to the spare input on the GAL asuming that there is logic space, and have the firmware do some tests to determine the machine type ? Like looking at the onboard ROMfor example and then configure accordingly.

are you sure you don't want me to do a CPLD version

Mind this will be somewhat more difficult if you don't have a TS1500

Cheers.

Phill.

[sirmorris]

The PIC can't drive the address lines so remotely examining the ROM is out of the question. There isn't any room in the GAL for multiple-choice routes through the code. Shame

C

[Prime]

The PIC can't drive the address lines so remotely examining the ROM is out of the question. There isn't any room in the GAL for multiple-choice routes through the code. Shame

You mis understood, have the Z80 code in your rom do the tests then command the PIC to toggle a pin....ZXpand uses 20v8 GALs doesn't it ? Would a 22v10 help with the logic, as it has the same pinout ?

Cheers.

Phill.

[sirmorris]

There's no way of telling what's in the machine unless I do some real nasty stuff like install a m/c routine in RAM which disables the overlay, checks the ROM version then re-enabled the overlay and returns the type code.

This would take up way too much room in the ROM - i'm down to my last couple of bytes as it is

I would be able to tell though - the ts1500 and zx81 ROMs are different. I haven't examined the differences in too much detail but if I said I was surprised that ZXpand works on this machine then that would be a huge understatement..!

C

[Prime]

There's no way of telling what's in the machine unless I do some real nasty stuff like install a m/c routine in RAM which disables the overlay, checks the ROM version then re-enabled the overlay and returns the type code.

This would take up way too much room in the ROM - i'm down to my last couple of bytes as it is

though there may be abother way.....

I remember someone saying that the TS1500, if it detects external RAM, will re-map the internat RAM into the 32K-48K reigon, ZXpand by default has ram from 8K-40K. So to test, write something to the top of the area say at $BF00, check that it reads back ok, and check that it's not an echo of some lower RAM address.

Ok you prolly have not got room for that either......

Perhaps for V2, you should have a 16K rom, and page the upper 8K between that and RAM, that way you could have any test code in there and page it out after it's not needed.....

I would be able to tell though - the ts1500 and zx81 ROMs are different. I haven't examined the differences in too much detail but if I said I was surprised that ZXpand works on this machine then that would be a huge understatement..!

Cheers.

Phill.

[yerzmyey]

Hi there.

I have some questions.

1) Where to buy ZXPand?
2) What would be the price?
3) Is there any WWW site that contains all required informations, photos and so on?

Thx.
Y

[Paul]

Hi Y

http://www.rwapsoftware.co.uk/zx812.html

Hi there.

I have some questions.

1) Where to buy ZXPand?
2) What would be the price?
3) Is there any WWW site that contains all required informations, photos and so on?

Thx.
Y

[RWAP]

Also, get yourself on the waiting list

[yerzmyey]

Thanx a lot guys. The site is what I was lookin' for.

Now - some questions.


1) Erm... I know it's actually offtopic but can anybody send me the RZ.P file that is present on this video?
http://www.youtube.com/watch?v=hvgdcpwp ... r_embedded
They released it as some WAV with turbo but they fucked up the recording so I can't load it into my ZX81. if I had the *.p, I could finally see it on real hardware.
Sorry for off-topic.

2) Well, the machine seems to be powerful. But the configuration is very complicated for a normal user. Is it possible to get a device already configured?

3) I noticed one thing:
CAT
CAT directory
LOAD "directory/file"
Is it possible to skip the "directory/" part when I'm already in the directory?

4) Where can I find the waiting list?

Thx again,
Y