Taneli Lukka's point of view:
The C=128 is really just an expensive C=64, atleast
for the normal hobby user. The C=128-mode has a pretty powerful basic and
other new features, but the most important selling factor: games, never
appeared because developers were afraid that they might lose the huge C=64
user base by concentrating on the C=128 and as a result only very few
games were made together with some "serious" programs. Some disk
based C=64 games do take advantage of the C=128 by having an auto boot
feature, like most Amiga games, but there are very few games like that,
Project Stealth Fighter from Micro Prose is one.
The CP/M mode is pretty useless too because it is quite slow. The Z80 has
to be slowed down so that the I/O circuits can keep up with it. Really
great engineering from Commodore.
For todays user the main problem is the power supply which was only used
with the C=128 and as a result finding a new one if the original stops
working or gets lost is very difficult indeed.
Music makers also dislike this model like the C=64c because the SID-chip
sounds diffirent than the original.
Shaun reports to us:
I was reading you information about the Commodore
128 with great interest. It's nice to know that you got so many things
correct. You did however leave out the expandable bit. Both the 128 and
128d can be internally expanded to 1,024kb, as the 8502 chip can handle
16 banks of 64k. All 16k vdc ram can be upgraded to 64k - this allows
you to handle hi-res colour interlacing (640x400) and colour mixing upto
4096 colours (the same resolution and colour amount as the older Amigas).
Also, all models of the Commodore 64/64c and 128/128d
can, thanks to an American company, be extrenally upgraded to 16mb. (Commodore,
themselves, used to make ram expansions for the C64/128 upto 512k, which
could be made upto 2mb.)
In 1995, a company called Creative Micro Designs,
decided to develop an accelerator card which would allow use of standard
72-pin simms ram upto 16mb. After much development, they where sucessful
- the 128 version of this upgrade was not for another year or so, but
now you can buy accelerator cards/ramcards for your C64 and 128 - in theory,
as this accelerator is compatible with the old Commodore ram expansions,
the maximum memory for the C64 is 34mb and for the 128 is 35mb (remember
- C128 allows1mb internal also!)
CMD (Creative Micro Designs) made a lot of C64
hardware between 1986-1997, and where still selling these upgrades in
2000/2001 - the Commodore part of the operation was then sold to Click
Here Software, who still continue CMD's legacy.
If you can imagine for a minute, I have sitting
in my spare room the following system - set and and fully working;
Commodore 128 - 16bit 65c816s processor at 20mhz
and 16mb's simms (SCPU Accelerator and SuperRAM card) - 16mb Ram disk
(upto approximately 256k per second loading - a lot faster than 50k per
5 seconds on the old 1541!!) - inteligent 3 button mouse with y2k compatible
real time clock - 3.5" disk drive formatting upto 1.6mb per disk
and fast data transfers - Printer interface running Canon BJC 4100 - 1571
and other authentic Commodore drives.
Now, you may ask yourself, how compatible is all
of this stuff? Well, each device may be switched out, and the accelerator
can be switched down to 1/2mhz, so for backwards compatibility, it's 100%
in a roundabout sort of way - or in other words I don't have to plug/unplug
all the upgrades depending on what I want to do.
Ron Shirley adds:
I have just been looking through your website and
i must admit i am very impressed. However in the commodore c128d information,
Imust question part of the report from "shaun" where he says
that the 64k vdc upgrade for the c128d enables 4096 colour mixing.
To the best of my knowledge all the 64/128 video
output is limited to 4bit (only the lowest 4 bits are connected, the upper
4 bits don't do anything) this gives a limitation of only 16 colours.
The 16/64k vdc is only used in cpm mode using the "RGBI" output
socket in 40 column mode you can use the 64k vdc as a data cache when
copying disks, many copiers such as "maverick" made use of the
64k vdc if available (the vic ii chip is used in 40 column mode not the
vdc so its memory can be used).
As for upgrading the memory internally to 1MByte,
all the memory chips in the 128 are soldered in place and there are no
available sockets to support such an
upgrade internally. It's true that the c128 supports memory banking but
it's not to support 1 MByte of internal memory but to support the 2x 64k
banks in various configurations due to the limitations of the 8bit processor
it can only access 64k at a time. It therefore has to have enough memory
bank options to support both 64k
banks and each bank with or without basic or kernal roms e.t.c.
bank 0 ram(0) only
1 ram(1) only
2 ram(2) only (same as 0)
3 ram(3) only (same as 1)
4 internal rom,ram(0),I/O
5 internal rom,ram(1),I/O
6 internal rom,ram(2),I/O (same as 4)
7 internal rom,ram(3),I/O (same as 5)
8 external rom,ram(0),I/O
9 external rom,ram(1),I/O
10 external rom,ram(2),I/O (same as 8)
11 external rom,ram(3),I/O (same as 9)
12 kernal and internal rom (low), ram(0),I/O
13 kernal and external rom (low),ram(0),I/O
14 kernal and basic rom, ram(0), character rom
15 kernal and basic rom, ram(0),I/O
Some items missed out:
The c128 can run in either 1 or 2 Mhz mode but none of the other chips in the c64 mode can support 2 Mhz so the screen
is switched off and the ports are disabled. It can be accessed by :
LDA #$00 = 1 mhz
LDA #$01 = 2 mhz
This caused compatability problems with some
tape loaders they were overwriting the area $d000 and up (sprite pointers)
causing the machine to crash.
Another bit of trivia:
The tape version of the game "yie ar kung fu" does not work on
the 128D , this is because of copy protection which forces you to switch
off your disk drive during tape loading. a bit dificult (but not
impossible) on the 128D.
Possible damage can be done to the buffer device
controlling the keyboard and joystick ports on the c128. The c64/128
uses shared locations between joystick port-0 and some of the keyboard.
When an autofire joystick is used for an extended period of time it
can damage the locations in the buffer device causing a strange effect.
When you unplug the joystick and switch on the c128 everything appears
normal until port-0 is read by a program or game, the locations inside
the buffer device then latch causing several keys on the keyboard to
stop responding until the power is switched off and then on. I have
noticed 4 or 5 machines with exactly the same cause and effect.
Best hardware upgrade.
The phantom parallel board for the cbm1541 diskdrive it took loading times
from 0sec-2mins without the board to 0sec-4sec with the board
(incredible!). Both sets of times are without software turboloaders.
More information about the Z80 and
VDC chips, by Michael Huth:
The Z80 runs in a weird timing to be
compatible to the VIC II. The VIC II uses 16 KB of the main ram and the
VDC can use upto 64KB seperated ram. The C128 was delivered with 16KB
seperated ram for the VDC. The speed of the 8500 in C128 mode is at 1 MHz
exactly the same as in C64 Mode. In 2 MHz mode its a little faster than 2x
because of the VIC II badline cycles missing. The VDC itself is clocked
completely independent and asynchroneus. (about 2MHz and VDC RAM at 16