Most people will remember the Commodore 64 as the classic breadox with the rainbow label (logo). However, when Commodore released the first C64s, they didn’t have this label (logo), but had a silver logo with the text “Commodore” and a silver “64″ next to the power LED.

The keyboard of this C64 Silver is pretty rare and is absolutely identical in the shape to that of Commodore’s PET computer (however, on the Commodore 64 side the PET’s number pad was replaced by four wide function keys, the remaining holes are covered with tape).

The motherboard used is the the original Rev.A ASSY 3262980 with the Video Chip (VIC II) ceramic and has also a 5-pin video connector instead of the 8-pin connector that later boards had. It means there’s not separate chroma signal available in a 5-pin video connector. In other words: no S-Video, only composite available via the video port.

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The Commodore 64, commonly called C64, C=64 (after the graphic logo on the case), occasionally CBM 64 (for Commodore Business Machines), or VIC-64, is an 8-bit home computer introduced in January 1982 by Commodore International.

Due to changes in the computing industry since its release, people claim it’s the highest selling computer of all time. This claim is disputed, because various changes were made to the “Commodore 64″, making the CP/M plug in cartridge incompatible with all but some 1982 production models, as well as the computer being revamped and placed into a new case, then its name changed to Commodore 64C, indicating that there were at least 3 different models in this range of computers.

Volume production started in early 1982, with machines being released on to the market in August at a price of US$ 595.[7][8] Preceded by the Commodore VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes (65,536 bytes) of RAM, and had favorable sound and graphical specifications when compared to contemporary systems such as the Apple II, at a price that was well below the circa US$1200 demanded by Apple, but the same couldn’t be said of the Tandy Color Computer, which was initially priced at $399.

source: wikipedia mos6502.com

Autopsy:

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The computer Lemon II is a “perfect” clone of the Apple ][+ (Apple Europlus) produced in Italy by different companies, Selcom, Jen, Belton and Lemon Italy.

The mainboard was a copy almost identical of the Apple ][+, differ from the original for a few details, such the use of EPROM instead of ROM.

The contents of the ROM was slightly modified to remove any reference to Apple. So the boot screen that show “Apple II” are replaced with “Lemon II”. The Lemon II was therefore not only a computer “compatible” like the original, but a real clone.

The computer won the fame of 100% software compatibility, feature that will determine the commercial success.

This text was taken from the homepage of computerhistory.it and translated in English language.

Playing at Montezuma’s Revenge:

Lemon II at work in a school laboratory:

source: computerhistory.it leganerd.com

I have received a Lemon II computer (Apple ][+ / Europlus Clone) in a good cosmetic condition but with a serious problem at the keyboard, here below defects and repairs that has been made.

Cleaning comparison (before / after):

Gallery of the repair:

Defects:

• First problem: When a keyboard key is pressed is always displayed the same character, in this case the character “O”
• Second problem (which i have only noticed after solving the first one): The keyboard works correctly, all characters are displayed in the correct way, but sometimes the character displayed does not match with the key pressed. Example: when pressing many times the letter “I”, after a while is displayed the character “Y” and after a while it show the right character “I”.

Components Replaced:

• 2 x 74LS191 (UP/DOWN Counters)
• 1 x SMC KR2376-ST (Keyboard Encoder)

I have to thank my friend Luca that called me to inform me that there was still a piece of the SMC KR2376-ST available in the store.

Autopsy:

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The Philips Monitor CM8802/00G is an excellent RGB monitor 14” suitable to use with Amiga and Atari ST.

Electronically is identical to the monitor Philips CM 8833, but compared to the latter one we can’t find the TTL RGB (DIN) input and the switching for Color/Monochrome, but is always present the composite (RCA) and Audio which makes it perfectly for computers with this type of output.

Cleaning comparison (before / after):

Defects:

• Missing RED Color.
• Out of focus.
• Convergence and saturation of colors.
• The monitor turns off by itself.

Works that have been made:

• Redone cold solder joints on PSU and CRT PCB.
• Focus, Colors and Convergence Adjustment.
• Cleaning.

Download:

• Philips CM8802-CM8833 Manual (4590)
• Philips CM8802-CM8833 Service Manual (1901)

Autopsy:

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The VIC-20 (Germany: VC-20; Japan: VIC-1001) is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore’s first personal computer, the PET. The VIC-20 was the first computer of any description to sell one million units.

The VIC-20 was intended to be more economical than the PET computer. It was equipped with only 5 kB of RAM (of this, only 3.5 KB were available to the BASIC programmer) and used the same MOS 6502 CPU as the PET. The VIC-20′s video chip, the MOS Technology VIC, was a general-purpose color video chip designed by Al Charpentier in 1977 and intended for use in inexpensive display terminals and game consoles, but Commodore could not find a market for the chip. As the Apple II gained momentum with the advent of VisiCalc in 1979, Jack Tramiel wanted a product that would compete in the same segment, to be presented at the January 1980 CES. For this reason Chuck Peddle and Bill Seiler started to design a computer named TOI (The Other Intellect).

The TOI computer failed to materialize, mostly due to the fact that it required an 80-column character display which in turn required the MOS Technology 6564 chip. However, the chip could not be used in the TOI since it required very expensive static RAM to operate fast enough. In the meantime, freshman engineer Robert Yannes at MOS Technology (then a part of Commodore) had designed a computer in his home dubbed the MicroPET and finished a prototype with some help from Al Charpentier and Charles Winterble. With the TOI unfinished, when Jack Tramiel was confronted with the MicroPET prototype, he immediately said he wanted it to be finished and ordered it to be mass-produced following a limited demonstration at the CES.

source: wikipedia

Autopsy:

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Olivetti S.p.A. is an Italian manufacturer of computers, tablets, smartphones, printers and other business products such as calculators and fax machines. Headquartered in Ivrea, province of Turin, the company has been part of the Telecom Italia Group since 2003.

The primacy of the first PC can be assigned to Olivetti thanks to Programma 101, which was produced in 1964 and had a big success in the U.S. market.

Olivetti’s first modern personal computer, the Olivetti M20, featuring a Zilog Z8000 CPU, was released in 1982. In 1983 Olivetti introduced the M24 and in 1984 the M21 (the first and last of transportable of Olivetti), a clone of the IBM PC using DOS and the Intel 8086 processor (at 8 MHz) instead of the Intel 8088 used by IBM (at 4.77 MHz).

The M24 was sold in North America as the AT&T 6300. Olivetti also manufactured the AT&T 6300 Plus, which could run both DOS and Unix.

The comparison (before / after):

Repairing & things before of the Cleaning:

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Defects:

• Mirror image.
• Sometimes garbled image with using the ISA Bus.

Replaced parts:

• Replaced a 74LS245N on the motherboard side.
• Replaced a 75LS244N on ISA expansion Module.
• Removed the battery for the Realtime Clock.

Upgrade:

• Bios v1.36 to v1.43 (latest).

source: wikipedia

Autopsy:

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Kaypro Corporation, commonly called Kaypro, was an American home/personal computer manufacturer of the 1980s. The company was founded by Non-Linear Systems to develop computers to compete with the then-popular Osborne 1 portable microcomputer. Kaypro produced a line of rugged, portable CP/M-based computers sold with an extensive software bundle which supplanted its competitors and quickly became one of the top selling personal computer lines of the early 1980s.

While exceptionally loyal to its original consumer base, Kaypro was slow to adapt to the changing computer market and the advent of IBM PC compatible technology. It faded from the mainstream before the end of the decade and was eventually forced into filing for bankruptcy in 1992.

Kaypro began as Non-Linear Systems, a maker of electronic test equipment, founded in 1952 by Andrew Kay, the inventor of the digital voltmeter.

In 1981, Non-Linear Systems began designing a personal computer, called KayComp, that would compete with the popular Osborne 1 transportable microcomputer. In 1982, Non-Linear Systems organized a daughter company named the Kaypro Corporation and rechristened the computer with the same name.

The first product, the Kaypro II, carried the Roman-numeral designation because one of the most popular microcomputers at the time was the Apple II. The Kaypro II was designed to be portable like the Osborne. (When battery-powered laptop computers became available, the larger machines came to be called transportable or luggable, rather than portable.) Set in an aluminum case, it weighed 29 pounds (13 kilograms) and was equipped with a Zilog Z80 microprocessor, 64 kilobytes of RAM, and two 5¼-inch double-density floppy-disk drives. It ran on Digital Research, Inc.’s CP/M operating system, and sold for about US$1,795.00.

Kaypro’s first computer, the Kaypro II, had a 2.5 MHz Zilog Z80 microprocessor; 64 Kb of RAM; dual, single-sided, 191 kB 5¼ inch floppy disk drives; and an 80-column, green monochrome, 9″ CRT.

Early in the Kaypro’s life, there was a legal dispute with the owner of the Bigboard computer who charged that the Kaypro II main circuit board was an unlicensed copy or clone.

he outer case was constructed of painted aluminum. The computer featured a large detachable keyboard that covered the screen and disk drives when stowed. This and other Kaypro computers (except for the Kaypro 2000) ran off regular AC mains power and were not equipped with a battery.

The comparison (before / after):

Defects:

• Black screen of death.

Replaced parts:

• Removed the filter capacitors.
• Replaced some Electrolytic Capacitors exhausted (PSU).

source: wikipedia

Gallery of the repair:

Defect:

• Black screen of death.
• Improper adjustment of Contrast and Brightness.
• Power Supply “tired”.

Replaced parts:

• Removed the filter capacitors.
• Replaced all Electrolytic Capacitors exhausted .
• Contrast and Brightness adjustments.

Autopsy:

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TRS-80 (“Tandy/Radio Shack, Z-80 microprocessor”) was a brand associated with several desktop microcomputer lines sold by Tandy Corporation through their Radio Shack stores.

The original “TRS-80 Micro Computer System” launched in 1977 (later known as the Model I) was one of the earliest mass-produced personal computers. The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small-businesses. Tandy Corporation’s leading position in what Byte Magazine called the “1977 Trinity” (Apple, Commodore and Tandy) had much to do with Tandy’s retailing the computer through more than 3,000 of its Radio Shack storefronts. Notable features of the original TRS-80 included its full-stroke QWERTY keyboard, small size, its floating point BASIC programming language, an included monitor, and a starting price of US$600 (equivalent to US$2,230 in 2011). The pre-release price was US$500 and a US$50 deposit was required, with a money back guarantee at time of delivery.

In July 1980 Tandy released the Model III. The improvements of the Model III over the Model I included built-in lower case, a better keyboard, 1500-baud cassette interface, and a faster (2.03 MHz) Z-80 processor.

With the introduction of the Model III, Model I production was discontinued as it did not comply with new FCC regulations as of January 1, 1981 regarding electromagnetic interference. The Model I radiated so much interference that while playing games an AM radio placed next to the computer could be used to provide sounds.

The Model III could run about 80% of Model I software, but used an incompatible disk format. Customers and developers complained of bugs in its BASIC and the TRSDOS operating system. The computer also came with the option of integrated disk drives.

Download:

• TRS-80 Model III Games Compilation in DMK/JV3/IMD Format (1437)
• TRS-80 Model III LDos v5.31 in IMD Format (1398)

Video of some games with sounds:

source: wikipedia

Autopsy:

The HS2 is a joystick adapter to improve the playability (like a Arcade/Coin-op). The adapter is compatible with the consoles ColecoVision & Atari 2600.

Autopsy:

The LO>>PROFILE professional keyboard is the ultimate upgrade for your Spectrum. By replacing its existing keyboard with a high quality LO>>PROFILE, you give this world-beating computer the keyboard it deserves.

The LO>>PROFILE is a full size QWERTY keyboard with full-travel positive-actions keys for super-fast entry of programs and data. Presented in an ultra-modern and robust enclosure, the LO>>PROFILE is elegantly styled and is inclined forwards for convenient operation.

Featuring a full size space bar with dedicated numeric and cursor keypad the LO>>PROFILE increases the number of keys from 40 to 53. A combination of clearly labelled, sculptured and height-adjusted keys aids the advance to fault-free touch-typing.

Descriptions are taken from the Advertising of the LO>>PROFILE keyboard.

I thank a friend for the donation.

Donated item:

• Homebrew RTTY demodulator for Commodore 64.
• Software and Documentations.

Like we know well the keyboard of the Commodore 116 may NOT be fixed because you can’t open it without break it.

The only way is break the plastic pins that hold the keyboard PCB and find the right way to close the whole thing, i leave you the right way for do this.

Once you have open it, we realize that this keyboard is a colossal shit, the conductive material of the keys is ridiculous a thin layer that is consumed very briefly.

The only way before you throw it is use the “Kontakt Chemie Graphit 33” but without spraying directly on the tiny conductive part of the key but first try on a plastic surface and then with a very fine brush take the graphite to paint the conductive part of the key.

The “Kontakt Chemie Graphit 33” with the days/months or years tends to dry, this solution make a new life to the keyboard, but not for always.

Another classic failure and is the FPC Connector (18 pins) for the keyboard flat that can be easily replaced if you find an FPC connector with 18 pins ;-D

The conditions of this Commodore 8296 (TAN Case) are really bad. The CBM 8296 is left for over 25 years in a dovecote.

The cleaning, repairing and restoration have taken a very long time, but the result is more than acceptable.

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Defects:

• The Commodore 8296 was completely dead (Black screen of death).
• Little problems of CRT geometry.

Replaced parts:

• Replaced PLA U6 with a OTP EPROM 27C512R 70ns + Adapter
• Replaced the ROM 2 x 2764 Eprom with 1 x 27C128 Eprom (spare parts from a original cbm pcb)

Note:

I have replaced the original ROM (2 x EPROM) pcb because the PLA adapter is fat. I could insert a small castle (photo) between the ROM pcb and the Main Motherboard but in this time i have prefered to replace with a single Eprom.

Gallery of repair and cleaning:

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Autopsy:

This product is GVP’s flagship SCSI controller.

This controller has room to mount, directly on the card, a 3.5″ SCSI hard drive as well as the capability to hold up to eight (8) megabytes of Fast RAM.

Download: GVP Impact A2000 Manual (1876)

source: amiga.resource.cx