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Commodore 128
Type Home computer
Released 1985
Discontinued 1989
Processor MOS Tech. A home computer was a class of Personal computer entering the market in 1977 and becoming common during the 1980s 8502 @ 2 MHz
Zilog Z80A @ 4 MHz
Memory 128 KB
Operating system Microsoft BASIC 7. A kilobyte (derived from the SI prefix Kilo -, meaning 1000 is a unit of Information or Computer storage equal to either 1024 0
Digital Research CP/M 3. 0

The Commodore 128 (C128, CBM 128, C=128) home/personal computer was the last 8-bit machine which was commercially released by Commodore Business Machines (CBM). A home computer was a class of Personal computer entering the market in 1977 and becoming common during the 1980s A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated Eight-bit CPUs normally use an 8-bit data bus and a 16-bit address bus which means that their Address space is limited to 64 KBs This is not a "natural Commodore, the commonly used name for Commodore International, was a US-American Electronics company based in West Chester Pennsylvania Introduced in January of 1985 at the CES in Las Vegas, it appeared three years after its predecessor, the bestselling C64. Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) The International Consumer Electronics Show (CES is a Trade show held each January in Las Vegas, Nevada, and is sponsored The Las Vegas metropolitan area includes the Las Vegas Valley a 600-square-mile (1600 km² basin and surrounding areas that is part of Clark County in southern The primary hardware designer of the C128 was Bil Herd. Bil Herd was a designer of 8-bit Home computers while working for Commodore Business Machines in the early-to-mid 1980s

Contents

Technical overview

Original Commodore 128 box
Original Commodore 128 box

The C128 was a significantly expanded successor to the C64 and unlike the earlier Plus/4 it remained compatible. The Commodore Plus/4 was a Home computer released by Commodore International in 1984 The new machine featured 128 KB of RAM (externally expandable to 640 KB) and an 80-column RGB monitor output (driven by the 8563 VDC chip with 16 KB dedicated video RAM, although following the release of the 128D later "flat" 128s had 64 KB of VRAM), as well as a redesigned case/keyboard with a numeric keypad. A kilobyte (derived from the SI prefix Kilo -, meaning 1000 is a unit of Information or Computer storage equal to either 1024 The 8563 Video Display Controller ( VDC) was an Integrated circuit produced by MOS Technology. In Computing, a keyboard is an Input device partially modelled after the typewriter keyboard which uses an arrangement of buttons or keys The 128's power supply was vastly improved over the 64's troublesome design. It was much larger, with cooling vents and a fuse to protect it from blowing up. Instead of the 6510 CPU of the C64, the C128 incorporated a two-CPU design. The MOS Technology 6510 is a Microprocessor designed by MOS Technology Inc The primary CPU, the 8502, was a slightly improved version of the 6510; its main addition was the ability to run at a 2 MHz clock rate (however, this required turning off the 40-column video output). The MOS Technology 8502 was an 8-bit Microprocessor designed by MOS Technology and used in the Commodore 128. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The second CPU was a Zilog Z80 which was used for ensuring CP/M compatibility and for mode-selection of the computer upon boot-up. The Zilog Z80 is an 8-bit Microprocessor designed and sold by Zilog from July 1976 onwards CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall The two processors could not run concurrently, thus the C128 was not a multiprocessing system. Multiprocessing is the use of two or more central processing units (CPUs within a single computer system

The C128 had three modes of operation: C128 Mode (native mode), which ran at 1 or 2 MHz with the 8502 CPU and had both 40- and 80-column text modes available; CP/M Mode, which used the Z80 second CPU in either 40- or 80-column text mode; and C64 Mode, which was very nearly 100% compatible with the earlier computer. In User interface design a mode is a distinct setting within a computer program or any physical machine interface in which the same user input will produce perceived different The term native mode is used in Computing in two related senses Text mode is a kind of computer display mode in which the content of the screen is internally represented in terms of textual characters rather None of these modes would have been possible as implemented on the C128 without the Z80 chip. The Z80 controls the bus on initial boot-up and checks to see if there are any C64/C128 cartridges present, and if the Commodore key (C64-mode selector) is active on boot-up. Based on what it finds, it will switch to the appropriate mode of operation.

Some 128s suffered from a reliability problem caused by the electromagnetic shield over the internal board. The shield had fingers that rested on the top of the major chips to conduct heat into the shield which then acted as a large heatsink. A combination of poor contact and the fact that plastic encased chips do not lose heat that way plus the shield being made from mu-metal (a poor heat conductor) saw some chips overheat and fail. Mu-metal is a Nickel - Iron Alloy (75% Nickel, 15% Iron, plus Copper and Molybdenum) that has very high magnetic The SID sound chip was particularly vulnerable in this respect as it operated from a 9 volt supply. The MOS Technology 6581/8580 SID (Sound Interface Device was the built-in Programmable Sound Generator chip of Commodore 's CBM-II, The situation could be vastly improved by removing the shield completely.

C128 Mode

C128 Motherboard
C128 Motherboard

While the C64's graphics and sound capabilities were generally considered excellent, the popular home computer was the subject of a number of perennial criticisms. A home computer was a class of Personal computer entering the market in 1977 and becoming common during the 1980s The 40-column VIC-II video display, while excellent for gaming, was often considered inadequate for productivity applications such as word processing. The VIC-II (Video Interface Chip II, specifically known as the MOS Technology 6567/8562/8564 ( NTSC versions 6569/8565/8566 ( PAL) is the microchip Word processing is the creation of documents using a Word processor. The lack of a numeric keypad was also an issue with some office suite software. In Computing, an office suite, sometimes called an office software suite or productivity suite is a Software suite intended to be used by typical Furthermore, the 2. 0 revision of Commodore BASIC that was incorporated into the C64 was quite limited, and lacked keywords to handle the system's graphical and sound capabilities. Commodore BASIC, also known as PET BASIC, is the dialect of the BASIC programming language used in Commodore International 's 8-bit Home These features had to be accessed via cumbersome PEEK and POKE commands, or by custom-written machine language routines. Also criticized was the lack of a hardware reset button, an essential device when developing assembly language routines. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler Finally, the C64's 1541 disk drive was almost universally condemned as slow and unreliable. Commodore64 fdd1541 backjpg|thumb|325px|Back panel view of the Commodore 1541 disk drive

The designers of the C128 succeeded in rectifying most of these concerns. A new chip, the VDC, provided the C128 with an 80-column color RGB display. The 8563 Video Display Controller ( VDC) was an Integrated circuit produced by MOS Technology. The new 8502 CPU was completely backward-compatible with the C64's 6510, but could run at double the speed if desired. The MOS Technology 8502 was an 8-bit Microprocessor designed by MOS Technology and used in the Commodore 128. The MOS Technology 6510 is a Microprocessor designed by MOS Technology Inc However, the VIC-II chip which controlled the 40-column display could not operate at the faster clock rate, so the 40 column display is not available in Fast mode. A numeric keypad was added to the keyboard, as were various other keys. The C64's rudimentary BASIC 2. 0 was replaced with the far more flexible and powerful BASIC 7. 0, which included keywords designed specifically to take advantage of the machine's capabilities, and also incorporated a sprite editor and machine language monitor. In Computer graphics, a sprite (also known by other names see Synonyms below is a two-dimensional/three-dimensional Image or Animation that A machine code monitor (aka Machine language monitor is software built into or separately available for various computers allowing the user to enter commands to view The screen editor was further improved. A reset button was added to the system.

Three new disk drives were introduced in conjunction with the C128, the 1570, 1571, and 3. The Commodore 1570 was a 5¼" Floppy disk drive for the Commodore 128 home / Personal computer. The Commodore 1571 was Commodore's high-end 5¼ " Floppy disk drive 5 inch 1581 drives promising far faster transfer speeds via a new "burst mode". The Commodore 1581 is a 3½ inch Double sided Double density Floppy disk drive made by Commodore Business Machines (CBM primarily for its With these three drives, more complex drive data arrangements were also made available to Commodore users in the nature of "track and sector" oriented subdirectories, a feature not available to PC users, who instead had to convolute their file allocation tables to do the same thing. The disk drives also had more on-board RAM than their predecessors, the 1540 and 1541 drives.

The C128 also had twice the RAM of the C64, and a far higher proportion was available for BASIC programming, due to the new MMU bankswitching chip. A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling This feature made it possible for BASIC program code to be stored separately from variables, greatly enhancing the machine's ability to handle complex programs.

The C128's greater hardware capabilities, especially the increased RAM, screen display resolution, and serial bus speed, made it the preferred platform for running the GEOS graphical operating system. GEOS ( G raphic E nvironment O perating S ystem) was an Operating system from Berkeley Softworks (later GeoWorks

CP/M Mode

The second of the C128's two CPUs was the Zilog Z80, which allowed the C128 to run CP/M; the machine came with CP/M 3. The Zilog Z80 is an 8-bit Microprocessor designed and sold by Zilog from July 1976 onwards CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall 0, aka CP/M Plus (backward compatible with CP/M 2. 2) and ADM31/3A terminal emulation. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing To make a large application software library instantly available at launch, the Commodore 128 CP/M and accompanying 1571 floppy disk drive was designed to run almost all Kaypro-specific CP/M software without modification. The Commodore 1571 was Commodore's high-end 5¼ " Floppy disk drive A floppy disk is an increasingly Obsolete data storage medium that is composed of a disk of thin flexible ("floppy" Magnetic storage medium encased Kaypro Corporation, commonly called Kaypro, was an American home / Personal computer manufacturer of the 1980s

Unfortunately, the C128 ran CP/M noticeably slower than most dedicated CP/M systems, as the Z80 processor ran at an effective speed of only 2 MHz (instead of the more common 4–6 MHz) and because it used CP/M 3. 0, whose complexity made it inherently slower than the earlier, more widespread, CP/M 2. 2 system. From the source code of the C128 CP/M implementation, it is clear that the engineers originally planned to make it possible to run CP/M in the "fast" mode as well, with the 40-column output turned off and the Z80 running at an effective 4 MHz; however, this did not work on the released C128 hardware.

A possibly unique feature of the C128 among CP/M systems was that some of the low-level BIOS services were executed by the 8502 chip instead of the Z80. In Computing, the BIOS (ˈbaɪoʊs The latter transferred control to the 8502 after having placed the pertinent parameter values in designated memory locations. The Z80 then turned itself off, being awoken by the 8502 at completion of the BIOS routine, with status value(s) available in RAM for inspection.

C64 Mode

By incorporating the original C64 BASIC and KERNAL ROMs in their entirety (16 KB total), the C128 achieves almost 100% compatibility with C64 software. The C64 mode can be accessed in one of three ways:

Some of the few C64 programs that fail on a C128 run correctly when the CAPS LOCK key is pressed down (or the ASCII/National key on international C128 models). The caps lock is a key on a Computer keyboard. Pressing it will set a keyboard mode in which typed letters are capitalized by default and (on some computers This has to do with the larger built-in I/O port of the C128's CPU. Whereas the SHIFT LOCK key found on both C64 and C128 is simply a mechanical latch for the left SHIFT key, the CAPS LOCK key on the C128 can be read via the 8502's built-in I/O port. The MOS Technology 8502 was an 8-bit Microprocessor designed by MOS Technology and used in the Commodore 128. A few C64 programs are confused by this extra I/O bit; keeping the CAPS LOCK key in the down position will force the I/O line low, matching the C64's configuration and resolving the issue.

A handful of C64 programs wrote to $D030 (53296), often as part of a loop initializing the VIC-II chip registers. In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a The VIC-II (Video Interface Chip II, specifically known as the MOS Technology 6567/8562/8564 ( NTSC versions 6569/8565/8566 ( PAL) is the microchip This memory-mapped register, unused in the C64, operated as a selector for 2 MHz mode in the C128. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Since it was not disabled in C64 mode, an inadvertent write could blank the 40-column display by putting the CPU into fast mode. Fortunately, very few programs suffered from this flaw. In July 1986, COMPUTE!'s Gazette published a type-in program that exploited this minor incompatibility, by using a raster interrupt to enable fast mode when the bottom of the visible screen was reached, and then disable it when screen rendering began again at the top. Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) COMPUTE!'s Gazette ( was a Computer magazine of the 1980s directed at users of Commodore 's 8-bit Home computers Publishing its first A type-in program, or just type-in, is a Computer program Listing printed in a Computer magazine or book meant to be typed in by the reader A raster interrupt is a Computer Interrupt signal that is utilized for display timing purposes By using fast mode during the vertical blank period, standard video display was maintained while increasing overall execution speed by about 20%. The vertical blanking interval (VBI also known as the vertical interval or VBLANK, is the time difference between the last line of one frame or field of a Raster [1] [2]

An easy way to tell the C128's C64 mode and a real C64 apart, typically used from within a running program, is to write a value different from $FF (255) to memory address $D02F (53295), which is used to decode the extra keys of the C128 (the numerical keypad and some other keys). In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a In Computer science, a memory address is an identifier for a memory location at which a Computer program or a hardware device can store a piece of data On the 64 this memory location will always contain the value $FF no matter what was written to it, but on a C128 in 64 mode the value of the location—a memory-mapped register—can be changed. Thus, checking the location's value after writing to it will reveal the actual hardware platform.

RAM setup

To handle the relatively large amounts of installable RAM, tenfold the 8502's 64 KB address space, the C128 used the 8722 MMU chip to create different memory maps, in which different combinations of RAM and ROM would appear according to bit patterns written into the MMU's confguration register. A memory management unit ( MMU) sometimes called paged memory management unit ( PMMU) is a Computer hardware component responsible for handling While the MMU was designed to handle more than 128 KB, the versions that were actually produced and used in the C128 cannot do so.

Although referred to as RAM expanders, Commodore's RAM Expansion Units were not expansion devices at all, as they utilized an external DMA controller to copy bytes between the C-128's RAM and the RAM in the "expansion unit. Commodore 's RAM Expansion Unit (REU range of external RAM add-ons for their Commodore 64 / 128 Home computers was announced at the Direct memory access ( DMA) is a feature of modern Computers and Microprocessors that allows certain hardware subsystems within the computer to access system " This function was essentially independent of the MMU's memory control features.

Commodore 128D

A Commodore 128D
A Commodore 128D

The Commodore 128D was released in the fall of 1985 in Europe. The US release date was in the summer of 1986. It was an updated version of the C128 with a detached keyboard and a 1571 disk drive in the same box as the main system unit, providing a sleeker, more professional-looking appearance, much like that of a desktop PC. In Europe the first C128Ds came in a plastic case with a side-mounted carrying handle and were technically exactly the same as a C128 with the 1571 disk drive. Additionally these models were equipped with a somewhat noisy cooling fan, leading to the model sometimes being referred to as the "128 Diesel".

Later models of the C128D came in a metal case; among these were the Commodore 128DCR (CR = cost reduced), which was widely sold in Canada and the USA. These later models had some minor improvements. The internal design was more integrated to save production costs, but also improved the thermal design, so that a fan was supposedly not needed anymore (later experience proved that the fan was a worthwhile addition and many C128Ds were so modified).

Inside, the C128D ROMs contained several bug fixes, and the 8563 VDC chip (in the C128DCR, the 8568) was equipped with the maximum capacity 64 KB of video RAM – four times that of the original C128. A software bug (or just “bug” is an error flaw mistake Failure, fault or “undocumented feature” in a Computer program that prevents it The 8563 Video Display Controller ( VDC) was an Integrated circuit produced by MOS Technology. The 8568 Video Display Controller (VDC, less commonly known as the DVDC, D = "Digital" was MOS Technology 's Graphics chip responsible for the This permitted the C128D to do higher-resolution graphics with more colors in RGB mode, although very little software took advantage of this. With or without the extra RAM, the VDC's high-resolution graphics modes were inaccessible from the C128's BASIC. They could only be utilized by calls to screen editor ROM primitives (or their assembly language equivalents), or via third-party BASIC language extensions. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler The most popular such toolkit was Free Spirit Software's "BASIC 8", which added high-resolution VDC graphics commands to CBM BASIC. BASIC 8 (or BASIC 80) &mdash " The Enhanced Graphics System For The C128 " &mdash developed by Walrusoft of Gainesville Florida and BASIC 8 was available on two disks (editor disk and runtime disk) and with a ROM chip for installation in the C128's internal Function ROM socket.

Market performance

The system architecture of the C128, which in case of a C128D with memory expansion included three CPUs, five types of RAM memory, three operating modes, two system speeds, two graphics chips and two completely different low-level floppy disk encoding schemes was positively baroque and not at all orthogonal. In Computer engineering, computer architecture is the conceptual design and fundamental operational structure of a Computer system In Mathematics, two Vectors are orthogonal if they are Perpendicular, i This high complexity was probably a factor in the limited success of the C128—but of course also much of the reason for the machine's popularity among long-time CBM users and 'hackers', who enjoyed the capability of full C64 compatibility in a computer which was also fully usable as a BBS terminal and general office application platform in 80-column mode running native or CP/M programs. A Bulletin Board System, or BBS, is a Computer system running software that allows users to connect and login to Another selling point for this group of users was the full-featured business keyboard, which was the first 'real' keyboard of a CBM computer since the less flexible (and thence, less popular) CBM-II/B series. The Commodore CBM-II series was a short-lived range of 8-bit Personal computers from Commodore Business Machines (CBM, intended as a follow-on

Because the C128 would run virtually all C64 software, and because the next-generation, 32/16-bit home computers, primarily the Commodore Amiga and Atari ST, were gaining ground, relatively little software for the C128's native mode appeared (probably on the order of 100–200 fully commercial titles, plus the usual share of public domain and magazine type-in programs). The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding The Amiga is a family of Personal computers originally developed by Amiga Corporation. The Atari ST is a home / Personal computer that was commercially available from 1985 to the early 1990s A type-in program, or just type-in, is a Computer program Listing printed in a Computer magazine or book meant to be typed in by the reader While the C128 sold a total number of 4 million units between 1985 and 1989, its popularity paled in comparison to that of its predecessor. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) This has been blamed on the lack of native software and on Commodore's less-aggressive marketing, which was mostly focused on the Amiga. An additional explanation may be found in the fact that the C64 sold huge numbers to people primarily interested in computer games, which the more expensive C128 didn't add much value towards improving (with the exception of a few Infocom text adventures). A personal computer Game (also known as a computer game or simply PC game) is a Video game played on a Personal computer, rather Infocom was a Software company, based in Cambridge Massachusetts, that produced numerous works of Interactive fiction. The C128 was certainly a better business machine than the C64, but not really a better gaming machine, and people who wanted business machines bought IBM PC clones almost exclusively by the time the C128 was released. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. With its advanced BASIC programming language, CP/M compatibility and "user-friendly" native software packages such as Jane, Commodore attempted to create a low-end business market for the 128, branding it a "Personal Computer" on the case, but this strategy was not successful in the face of low-cost IBM-compatibles like the Leading Edge Model D and Tandy 1000 that, in some cases, sold for less than a complete 128 system. CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall Jane 128 was a GUI -based Integrated software package for the Commodore 128 personal computer developed by Arktronics and released by Commodore The Leading Edge Model D was an IBM clone Computer released by Leading Edge Hardware during or before 1986. The Tandy 1000 was the first in a line of more or less IBM PC compatible Home computer systems produced by the Tandy Corporation for sale in its Radio There was a professional-level CAD program, Home Designer by BRiWALL, but again, most of this work was done on PCs by the 128s era. The main reason that the C128 still sold fairly well was probably that it was a much better machine for hobbyist programming than the C64.

Also, when the C128(D/DCR) was discontinued in 1989, it was reported to cost nearly as much to manufacture as the 16-bit Amiga 500, even though the C128D had to sell for several hundred dollars less to keep the Amiga's high-value marketing image intact.

Bil Herd commented on the Wikipedia C128 article, stating: "We considered the C128 to be a holding action until the next generation computers arrived, we were trying to up the game as far as expectations for new machines and buy a year, two at the max in the process. Bil Herd was a designer of 8-bit Home computers while working for Commodore Business Machines in the early-to-mid 1980s ***************************************************************************************** * * In that we exceeded our initial goals but probably due in part to Commodore's lackluster follow through on marketing and selling the Amiga. "

C128 esoterica

The 40 column version of the C128 Easter egg screen, with a listing of, and a message from, the machine's main developers. Notice the term "herdware", named after Bil Herd.
The 40 column version of the C128 Easter egg screen, with a listing of, and a message from, the machine's main developers. Notice the term "herdware", named after Bil Herd. Bil Herd was a designer of 8-bit Home computers while working for Commodore Business Machines in the early-to-mid 1980s

Specifications

External links

References

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