Talk:Commodore 128

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[edit] C128D release dates

I know the 128D was released in 1987 in the United States; I have the back issues of Run Magazine and Compute!'s Gazette that talked about the release. I believe I remember reading that the 128D didn't pass the FCC initially, so it was released earlier in Europe than it was in the United States.

Can anyone confirm the date of the 128D's European release? We need to note the discrepancy. I know that 1985 date isn't correct for the United States. In 1985 and 1986, all that existed in the States was the "flat" 128. --Dave Farquhar 13:08, 29 Jul 2004 (UTC)

I just checked one of my Gazette issues, and by their report from some winterly trade show the D model was definitely released in Europe in '85. One of my childhood pals actually had one. I'll try to find the months of release for both models -- I guess it's somewhere in the pile of mags. --Wernher 22:18, 9 Feb 2005 (UTC)

[edit] C128 trivia

I wrote the original part of the C128 trivia section (now in parantheses). I couldn't remember the exact memory address so I left it unfilled. The later, more specific addition (which is not in parantheses) seems to be talking about the exact same thing, but I am not fully sure. Could anyone confirm this? --Anonymous

But notice: one example says: [Write] 0xFF (255) to memory address 0xD02F (53295)[.] [...] On the 64 this memory location would always contain the value 0xFF no matter what was written to it[.]
while the other one goes: [M]onitor the contents of memory address TBC1 (<decimal value>)  for a while. A real 64 used this address as the internal hardware register TBC2 (<decimal value>), whose contents changed hundreds of times per second.
In other words, the two methods given as examples are somewhat opposite of each other. I'll try to find the address you mention in the latter example, as I sit on piles of CBM docs. Some day (or night) I might just bump into it. --Wernher 04:25, 9 Feb 2005 (UTC)
I am the "Anonymous" who wrote above. Thing is, I didn't remember the exact details about the way to distinguish the two computers, only that it involved writing something to a certain memory address and reading it back after a second or so. On a C64, you didn't get back what you wrote, but on a C128, you did. What you did get back on a C64 and why this was so had only become a blur. So it's entirely possible the second example is wrong. 85.76.152.179 20:23, 9 Feb 2005 (UTC)
Well, I'd say there's a good chance you're on to something that really exists, as "my" example does not at all call for a long delay between the write and read (more than a couple of instruction cycles, that is). But I'll put "your" example in wkp source comments (thus hiding it from the displayed article text while still keeping it in there) until we or someone else find the pertinent memory address. --Wernher 22:18, 9 Feb 2005 (UTC)

In this section is a bit about "unrealised multitasking". The article isn't entirely correct because those features (Multiple zero page and CPU stack locations) are not strictly needed for multitasking to be written for the C128 or even the C64. Pre-emptive multitasking was easily coded just by using the NMI and a timer interrupt, this would pop the current stack into memory, store the PC, restore the other stack context by pushing from a memory backup then finish by setting the PC. Multiple thread contexts could be created just by having more backup memory. Fnagaton 23:12, 5 June 2007 (UTC)

[edit] Other video processor: MOS 8568

I just opened up my C128D (according to circuit board: C128DCR). I can find the MOS 8566, but I cannot find the MOS 8563. It seems to be replaced by a MOS 8568, which is also shown on this page :

The MOS 8568 'VDC' or 'DVDC' outputs the 80 column digital RGBI modes of the 128. It was originally developed as an enhanced 'color 6845' for the CBM 900, Commodore's Zilog Z8001 machine. When its development was cancelled due to the purchase of Amiga Inc., the existing VDC design was integrated in the C128. However, two versions do exist: the MOS 8563 was used in the flat C128 and 'plastic C128D', the later MOS 8568 can be found in C128D-CR and the C128-CR prototypes.

I don't think I'd add it in the right way if I would try to do so, so can someone add it? --Gunix (altough not registered) 15:31, 29 October 2005 (UTC)

Thanks for the information; I didn't even know that chip existed! :-) I added it very discreetly, and also adjusted several other related pages accordingly. The 8568 should possibly get its own article, since due to its extra output signals it has a different pinout than its predecessor (this is mentioned in the source page you refer to---great reference to a lot of microchips; I hope the site's owner will allow the inclusion of his 8568 photo to the chips' forthcoming article). --Wernher 05:50, 30 October 2005 (UTC)

[edit] VIC-II in C128 mode

The VIC-II is available in native mode, isn't it? Mirror Vax 00:36, 6 March 2006 (UTC)

Indeed. All the C128 users who had no RGBI monitor would be in a bad fix if not. :-)   Incidentally, a cool feature that not many users had the opportunity to check out was the dual display capability of the 128's native mode: simultanously using the 40-col and the 80-col display---e.g. for showing graphics on the former and text (menus, src code, or whatever) on the latter. --Wernher 04:30, 8 March 2006 (UTC)
there were a couple 2-player adventure games published in ahoy magazine that used dual screens. —Preceding unsigned comment added by A plague of rainbows (talk • contribs) 16:54, 17 December 2007 (UTC)

[edit] Depending or not depending on x ?

From the Trivia section: "The Commodore 128's BASIC V7 [...] could be crashed or cause the computer to reboot by executing PRINT""+-[x] (where x is any integer), depending on the number entered for x."

This might seem somewhat ambigous: "x is any integer" and, at the same time, the outcome of the direct program line is "depending on [...] x". Is the real meaning behind this confusing statement something like the following: some value(s) of x will make the machine crash (i.e., freeze/lock up) while some other value(s) will make it reboot? If so, it would also be nice to know of some "working" :-) example values to put in the article. --Wernher 17:19, 17 March 2006 (UTC)

[edit] Bil Herd's comment

Tidied this up as a quote rather than a comment directly from the man himself. —Preceding unsigned comment added by 212.24.80.93 (talk • contribs) 17:45, 19 June 2006

[edit] Numeric Keypad

The main article would be improved if an inaccuracy were corrected. It implies that an unnamed suite of business software would not work because it couldn't find the numeric keypad. I don't remember if Commodore Business Machines actually offered its own "suite" of business software (CBM generally didn't offer very good software but relied on independent programmers to do that sort of thing for them, usually outshining the giant by miles) but there is a numeric keypad. If you bother to take a look, you will see that the numeric keypad exists just right of the keyboard. (If I recall correctly, you can distinguish keypresses on the keypad from those on the regular keyboard by testing a new line of I/O that was fortuitously mapped to address one of the bits in address $01.)198.177.27.21 07:47, 26 May 2007 (UTC)

The keypad sent different keycodes too. They were totally different keys that happened to be programmed have the same effect - lots of sw didn't work with it. —Preceding unsigned comment added by 69.125.110.223 (talk) 16:50, 19 December 2007 (UTC)

[edit] Fixing another inaccuracy

The C-128 works just fine in 2 mhz mode. The main article says you have to turn off your 40 column monitor to get it to work in 2 mhz mode. This simply isn't true. You just have to turn on an 80 column monitor. You are never required to turn off the 40 column monitor. To prove this is true, hook two monitors up to your C-128, one of the monitors being a 40 column monitor and the other being an 80 column monitor. Now you can switch back and forth from SLOW to FAST mode quite easily without ever turning a monitor off. You can leave both monitors turned on, and even output data to the separate monitors - and switch freely from 1 mhz to 2 mhz. There is never a requirement that you turn off the 40 column monitor. You can leave it turned on all the time that you are in 2 mhz mode. Just remember to plug an extra monitor into your computer so you can enjoy 80 column mode when you switch to fast 2 mhz mode.198.177.27.21 07:54, 26 May 2007 (UTC)

Perhaps the originator of the statement (that the C128 doesn't work in 2 MHz mode) simply thought of the fact that the 40 col monitor output (the VIC-II) didn't produce a legible signal in that mode? A bit of a letdown for those C128 owners that didn't own a (fairly expensive) 80 col monitor back in the day... But, as you say, the machine itself works just fine at 2 Mhz, no problem there. --Wernher 18:39, 14 July 2007 (UTC)
Commodore had the 1802 monitor for just those users. It was a composite monitor that produced a fuzzy but mostly-readable 80 column monochrome display on the 128. —Preceding unsigned comment added by 69.125.110.223 (talk) 18:37, 17 December 2007 (UTC)

[edit] Confusing Text About CP/M

I still own one of these machines and don't understand the following:

SPECS: Zilog Z80A @ 4 MHz CP/M Mode: ...Z80 processor ran at an effective speed of only 2 MHz...

The Z80 had to share the address and data buses with the 8502. Therefore, a bus cycle had to be 2 MHz to maintain hardware compatibility. CP/M on the 128 was a bit of a dog, and I, for one, was never able to understand why Commodore even bothered. By the time the 128 was available (late 1985) CP/M was rapidly falling out of favor.

BDD 06:51, 17 December 2007 (UTC)

They did it to give the computer a business-y cachet. They could say it ran wordstar, dbase etc never mind how many people would actually use that.69.125.110.223 (talk) 18:40, 17 December 2007 (UTC)

[edit] Added more HI-RES (NON YELLOWED) photos

Also added the original box photo. Too bad I don't have a better one but the computer itself looks good. And no yellowing! These computers are SO hard to find that are not yellowed.

cbmeeks 13:36, 11 September 2007 (UTC)cbmeeks

[edit] C128D

I reworded the comment about using PEEKs and POKEs to control the VDC. That was a very unreliable method, owing to the fact that those two BASIC verbs use LDA(xx),Y and STA(xx),Y addressing (where xx is a zero page pointer to the VDC registers). MOS Technology warned in the VDC documentation to not use indirect addressing to talk to the chip. The only reliable way to talk to the VDC from BASIC was by calling the screen editor ROM subs at $CDCC (write) and $CDDA (read).

BDD 06:59, 17 December 2007 (UTC)