Posted By
MIRKOSOFT
on 2016-05-22
12:12:07
|  Are addresses of Plus/$ at $D602-$D609 free?
Hi!
I'm beginner on Plussy scene.
I have important but very simple Q:
Are addresses of Plus/4 in range $D602-$D609 free?
Or they're used by <any> hardware? If, which - best from most important to lowest important list.
Are used by Plus/4 system or software or IO? If, what it uses and same list like above.
Thank you for support.
Miro
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Posted By
Litwr
on 2016-05-22
12:43:35
| Re: Are addresses of Plus/$ at $D602-$D609 free?
It is absolutely free to use as RAM. This area is also in Kernal ROM.
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Posted By
MIRKOSOFT
on 2016-05-22
13:04:51
| Re: Are addresses of Plus/$ at $D602-$D609 free?
Ok, hardware free.
It's occupied by Kernal.
Ok, is any area in $D500-$D800 free for IO or external use?
Not occupied by any chip IO, Kernal, chargen and hardware free.
If not in this area - which suggest you?
Thank you.
Miro
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Posted By
Litwr
on 2016-05-22
13:11:16
| Re: Are addresses of Plus/$ at $D602-$D609 free?
All area at $8000-$ffff is occupied by ROM. But it is switchable to RAM. Any write to this area will write to RAM. To read RAM is possible after writing to $ff3f, to read ROM - after writing to $ff3e. IMHO there are a lot of free space in the official i/o area at $FD00-FEff - this area is not used by ROM routines.
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Posted By
Csabo
on 2016-05-22
13:12:26
| Re: Are addresses of Plus/$ at $D602-$D609 free?
Heh, I read Litwr's first answer and though: "perfect response, no need to add anything" 
But apparently not? I'm a bit confused about what you're actually asking. First, the Plus/4's memory map is much simpler than the C64's - it's night and day. So let me just say this, in very generic terms:
- $1000-$FD00 is all yours to do as you please, if you page in the RAM (since by default, the ROM is visible above $8000).
- $1000-$8000 is all yours, in case you do want to page in the RAM.
By "all yours" I mean your software can use it for absolutely any purpose and nothing will affect it, unless you specifically do something that does.
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Posted By
siz
on 2016-05-22
16:53:09
| Re: Are addresses of Plus/$ at $D602-$D609 free?
My 2 cents: probably you want to add some kind of hardware expansion. On the 264 series computers I/O area is from $fd00 to $ff3f (in opposition with the C64's and C128's $d000-dfff).
This area is always mapped as I/O, you can't map it out. As the others said before: you always have RAM at $0002-$fcff and at $ff40-$ffff for read but you can turn on (in fact it's turned on by default) ROM instead of RAM $8000-$fcff and $ff40-$ffff.
Edit: I've copied Solder's I/O area map description to the Encyclopedia.
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Posted By
MIRKOSOFT
on 2016-05-22
18:22:06
| Re: Are addresses of Plus/$ at $D602-$D609 free?
For now only and nothing after: Yes, possible hardware.
I need to know if area $D602-$D609 can be used for interface IO.
You said not, ok, what area is best match for IO no interfereed by other hardware and system. System I mean Kernal or any routines without which Plussy can't work. Really don't know how is solved bankswitching - I mean it looks like must to be there 'cause have for Basic 60671 Bytes is impossible by simple turning off any part (like C64 simple turning off Basic or Kernal which makes it unaccessible).
You're asking why I found not documentation - I'm tasks overdosed and here I can find feedback from real users and that's different. Also RSS update has time less costs than checking/waiting for reply.
Thank you for understanding.
Miro
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Posted By
MMS
on 2016-05-22
19:27:49
 | Re: Are addresses of Plus/$ at $D602-$D609 free?
128K
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Posted By
gerliczer
on 2016-05-23
01:52:30
| Re: Are addresses of Plus/$ at $D602-$D609 free?
I really don't understand you, Miro. siz gave you a link to the currently known "port map" of the I/O area. This includes all reserved and unreserved addresses, and what are occupying them. (Yes, there are some places that are not sure if they are free.)
You should pick your 8 bytes window (something like $fd90-$fd97 - no, this is NOT a suggestion) and ask if this is really free or some other existing or planned hardware already occupies it. If it is free then use it. If it is occupied you either pick another address range or negotiate with the other party trying to reserve it.
What is so hard about that?
And I seem to remember that you already asked a question about the memory organisation of the TED machines which was answered back then. Or maybe I'm wrong, in which case I'm sorry.
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Posted By
SVS
on 2016-05-23
05:38:34
 | Re: Are addresses of Plus/$ at $D602-$D609 free?
Maybe MIRKOSOFT just want an easy suggestion. Well: do use $FD90-FDCF
As far as I know these addresses are used by no known hardware (original or mod) and reside in an area always present in all memory bank configurations.
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Posted By
gerliczer
on 2016-05-23
10:03:40
| Re: Are addresses of Plus/$ at $D602-$D609 free?
@JamesC: Why do you think it is SID related? The addresses he was talking about strangely align with the VDC port addresses ($D600-01) in a C128.
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Posted By
JamesC
on 2016-05-23
11:22:55
| Re: Are addresses of Plus/$ at $D602-$D609 free?
@gerliczer: In the third post of this thread, he asked for 8 bytes anywhere in the $D500-$D800 range, which is where the 64's SID registers mirror. And in the 6th post (his second reply), he doesn't understand bankswitching ... which any 128 ML programmer should, if they're coding for 128 mode.
I admit, it's only my theory. But it's logical.
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Posted By
gerliczer
on 2016-05-23
11:39:04
| Re: Are addresses of Plus/$ at $D602-$D609 free?
@JamesC: Take a look at this webpage: http://www.mirkosoft.sk/downloads.html. It is very probably his because it lists his Text Resizer utility. The Project page talks about something like an OS for the C128. I'd be very surprised if he not knew memory management. I think he has way more problems with English.
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Posted By
MIRKOSOFT
on 2016-05-23
15:31:21
| Re: Are addresses of Plus/$ at $D602-$D609 free?
Hi!
Truth is in my poor English.
Of course programming 128 without bankswitching is impossible, and really even programming OS.
I know bankswitching of C128 and memory configuring, shared memory etc.
I'm beginner on Plussy scene. We all know that C64 has nothing possible, only turning off Basic and/or Kernal. From this I began flirt with CP/M cartridge - C128 for switch to Z80 needs bankswitching and memconfig, but C64 it has not, so if it can switch to Z80, I tried to get back Z80 to C128 also when is SCPU128 active (Z80 inside C128 is by SCPU128 unaccessible) and success - works and even more. So I mean missing NMI in Plussy disabling other CPU can be false, any way can anybody find... I don't throw my guns to scrap for few problems.
Current problem is to make available $D602-$D609 for IO 'cause it can be common. I don't want to tell the secret when I don't know yet if will be fight success.
Miro
*my English is poor also for our Slovak double negotation:
"No, I don't stay here" in English means "I stay not here" or "I go away"
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Posted By
MMS
on 2016-05-24
04:06:01
| Re: Are addresses of Plus/$ at $D602-$D609 free?
Hi maybe the false NMI info originated from me. Few years ago I read a CP/M cartridge review, and maybe misunderstood something. The fact is (as gerliczer highlighted correctly) that NMI lines are not connected at all on the C64 CP/M schematics. Maybe just because noone developped an external CPU for plus/4 it does not mean it is impossible.
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Posted By
siz
on 2016-05-24
09:06:09
| Re: Are addresses of Plus/$ at $D602-$D609 free?
... or the schematics for the C64 CP/M cartridge is wrong.
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Posted By
gerliczer
on 2016-05-24
09:22:53
| Re: Are addresses of Plus/$ at $D602-$D609 free?
@siz: IDK if it means anything, but I took a peek at the C128 schematics and the /NMI pin of the Z80 is shown to be directly pulled up there, too.
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Posted By
MIRKOSOFT
on 2016-05-24
10:23:14
| Re: Are addresses of Plus/$ at $D602-$D609 free?
There is difference at that line.
SCPU128 causes this:
Disables 8502 - that means: not possible switch to internal Z80, tape port is unacessible
WDC65816 simply has 6502 emulation mode for replacing 8502, native is compatible in correct config, but both modes are in 65K architecture, so illegal opcodes are missing.
If external Z80 (cartridge) could had line to real 8502, then accessibility could be same as internal Z80.
But CP/M cartridge works also when is SCPU128 active, it means difference in that line.
Here it needs to say - don't exchange internal and external Z80 (inside C128 and inside cartridge).
Here you see why I think that maybe solution for external CPU for Plussy is possible.
Miro
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Posted By
gerliczer
on 2016-05-25
04:17:15
| Re: Are addresses of Plus/$ at $D602-$D609 free?
I'm curious what idea Miro will come up with. Ages ago TLC and others were discussing the possibility of forcing the CPU read a crash opcode in a controlled manner and taking over the system this way. Maybe he warmed up this concept.
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