litwr wrote:
bmeyer wrote:
You can most definitely access the VIC and the SID from the Z80 directly (you do *NOT* have to go through he 8502 to do it).
I wrote exactly about the same things but experts who tried to use the SID and VIC with the Z80 reported that it is possible only for very simple things because of timing issues and other problems. Do you know any demo for the Z80 using the SID or VIC?
Might be right but I have no idea. I was only ever considered myself a "user" of CP/M - I never actively developed in it (or for it). Yes, I wrote some tools to ease the pain with the cross-build process that we used for supporting various SBC control boards that I supported, and yes I could get it to make a beep and and whistle and those *DID* use the SID and played a simple chord but that was just for notification - nothing more. I will be honest and say that I didn't even write the routines that did it - I just called a utility from a SUB script to do it. From a technical perspective, there is *NO* reason as to why you can't access any I/O chip (sound, video, etc) from the Z80. They share the same bus. If there are timing issues, then it is probably down to the way that the Z80 itself works in conjunction with it's implementation in the 128.
You have sparked my curiosity though so I'll have to drag my C128DCR back out of the attic and fix it so that I can actually experiment with this (it's dead at the moment with a bad DRAM chip and I've just been completely slack about getting around to fixing it - been on my "I'll get around to fixing that one day" list of things for a few years now ...).
litwr wrote:
IMHO the C128 was good only as the C64. Basic 7 was slower than slow Basic 2.
Note sure I agree with this. It was both the slowest of the CBM basics, and also the fastest depending on if you were in "FAST" mode or not.
Part of the problem/benefit was that BASIC variables and program code were stored in a separate banks so BASIC was forced to switch back and forth continuously.
The BASIC7 was also significantly more advanced and therefore because it supported so many more features was naturally going to be slower. That said, I'll take BASIC7 over BASIC2 any day of the week, even if it was ~ 15% slower.
litwr wrote:
No support for the VDC was provided.
Pretty much. The VDC was an absolute b*******d of a chip. I think graphics was an afterthought and the VDC was only ever considered for text only.
litwr wrote:
The C128 was really a great marketing success for Commodore
Ok, this one I have to laugh at. Commodore marketing was abysmally bad at the best of times (at least it was here in AU). One of my mentors (he worked at Commodore AU) used to state that Commodore marketing weren't competent to to sell water to a man dying of thirst in the desert. Based on my own experience at the time dealing with the chip division (we used the MOS 6502s and 6526s in some of the PLC boards) that is 100% accurate.
litwr wrote:
IMHO they rather deceived ppl, they could make a much better computer... IMHO knowledgeable people should have bought the C64 and Amstrad CPC6128 instead of the C128 to get much better option.
As far as CP/M was concerned - maybe. I never had a CPC so I just don't know. I had a 128 because it had a Z80 in it *AND* it had a 6502 "like" processor in it, and was a semi-reasonable build system (albeit a bit slow). Being able to have just the one computer and not three was pretty important in the day.
litwr wrote:
Commodore even artificially cut MMU to support only 128 KB.
Ok if I'm to believe Bil (Herd) the MMU came straight from the LCD computer, and number of the "limitations" were inherited from that design. The lack of the 256Kb of RAM (one of my great bugbears) was a side effect of limitation of the LCD project (the 8722 was only half working when it came from the LCD machine and it needed a fair bit of additional work for the 128). How true that is, we'll probably never know as Dave (DiOrio) is now gone.