MEGA65 FORUM

RAM

append delete Freddy Champagne

In my opinion it is needed to be able to upgrade the board up to 8MB as this was the max. possible by design (iirc).
It is ok to start with 128k (better would be 256 or 512k) but CBM designed the c65 for up to 8MB, and thus I would like to know, if we can upgrade the ram.

Also would be nice to see some previews of the adapted geos. And maybe also a list of the 'Software Bundle' as stated on the website.

Also one question to LGB: would it be possible to insert a full Basic10 in xemu?
I read somewhere that Paul said that there exist a rom with Basic 10 full implemented.

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append delete #1. SvOlli

8MB was pure marketing talk. The specification of the RAM Expansion Control register only allowed for two banks of 512K each. There are still a couple of bits undefined, so more might be possible, but for the final state of the machine it was 1MB only. (Docs backing this up are available at https://github.com/MEGA65/c65-specifications ) 8M or maybe just 4M might have been included at a later state, as the register still has some bits unused.

Also there is no completed Basic 10. The most current ROM known so far (dated 911001) still contains several ?NOT IMPLEMENTED ERRORs.

append delete #2. Freddy Champagne

Inside CPU:

o Memory Mapper supporting up to 1 Megabyte address space

Then:
o Memory

o RAM -- 128K bytes (DRAM)
Externally expandable from additional 512K bytes to 4MB
using dedicated RAM expansion port.
[....]
o DMA -- Custom DMAgic controller chip built-in
Absolute address access to entire 8MB system map
including I/O devices, both ROM & RAM expansion ports.
List-based DMA structures can be chained together
Copy (up,down,invert), Fill, Swap, Mix (boolean Minterms)
Hold, Modulus (window), Interrupt, and Resume modes,
Block operations from 1 byte to 64K bytes
DRQ handshaking for I/O devices
Built-in support for (optional) expansion RAM controller

Altough I myself would already be very happy with 1MB. The 4 and 8MB 'option' would probably only be used as ramdisk.
I guess the DMAgic was planed to quicly move fetch and stash between the 1MB MMU memory and the external RAM trough the ram expansion port.
Similar as the DMA-chip in the Ram expantion did on the c128?

Puh. nach langem suchen wieder gefunden:

@ Highlander: The Hardware of the C65 was finished, but not all Basic- commands implemented in the latest Version of Basic V10 (as far as I know there should be commands like draw "circle" and other useful commands. Are you planning to implement the missing Basic V10 - commands? I think, that a 100%- working Basic V10, as planned from Commodore, would be perfekt, because with an easy to use Basic there will be more programmers for the C65. And just think about it: The first Commodore with a viable Basic...

Das letzte C65 ROM hatte alle BASIC commands, einschließlich CIRCLE etc, so kein Problem.
[The last C65 ROM has all BASIC commands, including CIRCLE etc, so no problem.]

Das wurde am 28 April 2015 von Paul so gepostet im www.forum64.de.

(sorry for the german, but in this world we all need to be multilanguaged ;) [Basic 2.0/7.0/10 % 6502+ ASM] ;-)

:: @Freddy Champagne added on 28 Apr ’18 · 00:05

s/%/&

;-)

:: @Freddy Champagne added on 28 Apr ’18 · 00:21

I just looked up the supposedly unfinished Basic commands: I read, that the following commands are not impolemented in all known Basic V10- Roms of the C65:
PAINT, PASTE, CUT, LOCATE, SCALE, WIDTH, QUIT, OFF, SET, VIEWPORT

They all should give an "?COMMAND NOT IMPLEMENTED ERROR".

Is that right or is there really a finished Version available?

That last ROM had those functions implemented. Wikipedia is wrong.

Paul.

(on April 29, 2015)

append delete #3. LGB

I'm not sure what did you mean about inserting full basic 10 into Xemu. Xemu/M65 is a hardware emulator, so it can run anything you 'feed" in, you only need the ROM image, much like the hardware that you can replace the ROM chip for sure. It's not like the "Hi65" which is basically a project being a "BASIC 10 emulator" without emulating the hardware. It's another question that - I think - there is simple no such thing "finished BASIC 10" ROM at all on our planet. Surely, it would be ideal somebody to disassemble existing BASIC 10 implementations from various ROM images with trying to bug fix + complete it, that wouldn't be an easy task though, but it's nothing to do with Xemu, but with BASIC 10 in general. Actually, Xemu has multiple emulators, now just thinking of its pure C65 emulation, it uses a ROM image file, you can specify any ROM image for it. For the M65 emulator, it emulated M65 more closely, eg you need an SD card image as the M65 needs an SD card, with the ROM image on the file system, so M65 kickstart can load it, like the "real" M65. It's up to you what kind of ROM image you can place on it (it's not even possible to put BASIC 10 ROM or any Commodore ROMs into it by default, or including it in Xemu, as it would be a license problem).

As for memory, the question is more about the context. Mega65 is more than only a C65 re-implementation it has its won ways to extend the idea of the C65. M65 has 28 bit address space, that is, basically 256Mbytes in theory. Many of the original C65 hardware elements are enhanced in M65 to allow to address the whole addressing space, including the DMA engine, CPU's support for MAP'ing memory (CPU memory mapper) and also new additions like zero page based linear addressing mode. Surely, 256Mbyte is a design information, still it depends on the actual implementation (future PCB for M65) what it can offer to connect things to, at which speed, and what amount of RAM it will hold by default. It's hard to say what C65 supported (now only C65, not M65 ...) as with eg REC (ram expansion controller) seems to have plans (just reading various preliminary documents, or even c65manual.txt), different versions. Honestly, I don't think - in any topic - we can say what C65 supported, since even existing C65s have different capabilities in many aspects, it was not a finished project at all. This is even true for the ROM/BASIC-10 btw ... Some of the ROM images you can find implements features simply does not work with other ROMs either giving implementation error, or not even known giving SYNTAX ERROR, or simply buggy, etc.

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