This is a little description of the repair of a Radio Shack TRS-80 Model 1 for a Friend.

The computer comes with several problems.

• Some IC are dead or in shorted state.
• Keyboard flat cable.
• One key “L” is dead.

Finding the cause of the fault has not been easy, i had to ask for a help to Ian, this dude is an expert of TRS-80 repairs.

How you can see from the photos, i had to replace a number of IC.

• 4 x Video RAM 2102 (Z62 / Z63 / Z46 / Z48)
• 1 x Z80 (Z40)
• 1 X 74LS157 (Z31)
• 1 X 74LS93 (Z32)

Stage of the defect (before and after):

Keyboard repair (replacement of internal contacts):

Micro Computer Technical Reference Handbook:

Download: TRS-80 Micro Computer Technical Reference Handbook (2497)

Autopsy:

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from Wikipedia:

TRS-80 was Tandy Corporation’s desktop microcomputer model line, sold through Tandy’s Radio Shack stores in the late 1970s and early 1980s, and 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 $600.

The pre-release price was $500 and a $50 deposit was required, with a money back guarantee at time of delivery. One major drawback of the original system was the massive RF interference it caused in surrounding electronics. Stricter FCC regulations on interference led to the Model I’s replacement by the Model III.

Radio Shack announced the TRS-80 (Tandy Radio Shack) at a New York City press conference on August 3, 1977. It cost $399, or $599 with a 12″ monitor and a Radio Shack tape recorder as datacassette storage. Before this, the most expensive product Radio Shack sold was a $500 stereo.

The company hoped that the new computer would help Radio Shack move into higher-priced products, and improve its “schlocky” image among customers. Small businesses were the primary target market, followed by education, then consumers and hobbyists. Despite its hobbyist customer base, Radio Shack saw hobbyists as “not the mainstream of the business”. Although the press conference did not receive much media attention due to a terrorist bombing elsewhere in the city that day, “six sacks of mail” arrived at company headquarters asking about the computer, and over 15,000 people called Tandy to purchase a TRS-80, paralyzing its switchboard.

Unlike competitor Commodore—which had announced its PET several months earlier but had not yet shipped any—Radio Shack began shipping computers by September. Still forecasting 3,000 sales a year, the company sold over 10,000 TRS-80s Model Is in its first one and a half months of sales, and over 200,000 during the product’s lifetime.

source: wikipedia

Commodore C16/C116 for Spare Parts donated by Damiano Colombari (Manosoft). Thanks Damiano.

Apple II Keyboard for Spare Parts donated by Paolo Cognetti. Thanks Paolo.

Autopsy:

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The CMOS battery is exhausted, the Hard Disk is deceased.

Thanks to Damiano (Manosoft) for his donation.

from Wikipedia:

IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones. They duplicated almost exactly all the significant features of the PC architecture, facilitated by various manufacturers’ ability to reverse engineer the BIOS using a “clean room design” technique. Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BUTTOX.

Many early IBM PC compatibles used the same computer bus as the original PC and AT models. The IBM AT compatible bus was later named the Industry Standard Architecture bus by manufacturers of compatible computers. The term “IBM PC compatible” is now a historical description only, since IBM has ended its personal computer sales.

Descendants of the IBM PC compatibles comprise the majority of personal computers on the market presently, although interoperability with the bus structure and peripherals of the original PC architecture may be limited or non-existent.

source: wikipedia

Autopsy:

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from Wikipedia:

The Atari ST is a home computer released by Atari Corporation in June 1985. It was commercially available from that summer into the early 1990s. The “ST” officially stands for “Sixteen/Thirty-two”,[2] which referred to the Motorola 68000′s 16-bit external bus and 32-bit internals. Due to its graphical user inferface, it was known as the “Jackintosh”, a reference to Jack Tramiel.

The Atari ST was part of the 16/32 bit generation of home computers, based on the Motorola 68000 CPU noted for 128 kB of RAM or more, a graphical user interface, and 3½” microfloppy disks as storage. It was similar to the Apple Macintosh and its simple design allowed the ST to precede the Commodore Amiga’s commercial release by almost two months. The Atari ST was also the first personal computer to come with a bit-mapped color GUI, using a version of Digital Research’s GEM released that February.

The ST was primarily a competitor to the Apple Macintosh and the Commodore Amiga systems. Where the Amiga had a graphics accelerator and wavetable synthesis, the ST had a simple frame buffer and a 3 voice synthesizer chip but with a CPU faster clocked, and had a high-resolution monochrome display mode, ideal for business and CAD. In some markets, particularly Germany, the machine gained a strong foothold as a small business machine for CAD and Desktop publishing work. The Atari ST also enjoyed some market popularity in Canada.

The ST was also the first home computer with integrated MIDI support. Thanks to its built-in MIDI, it enjoyed success for running music-sequencer software and as a controller of musical instruments among amateurs and professionals alike, being used in concert by bands and performers such as Jean Michel Jarre, Madonna, Eurythmics, Tangerine Dream, Fatboy Slim, and 1990s UK dance act 808 State, as well as naming German digital hardcore band Atari Teenage Riot.

The ST was later superseded by the Atari STE, Atari TT, Atari MEGA STE and Falcon computers.

In late 1989, Atari released the 520STE and 1040STE (also written STE), enhanced version of the ST with improvements to the multimedia hardware and operating system. It featured an increased color palette of 4096 colors from the ST’s 512 (though the maximum displayable palette of these without programming tricks was still limited to 16 in the lowest 320×200 resolution, and even fewer in higher resolutions), Genlock support, and a graphics co-processor chip called Blitter, which could quickly move large blocks of data (most particularly, graphics sprites) around in RAM. It also included a new 2-channels digital sound chip that could play 8-bit stereo samples in hardware at up to 50 kHz.

Two enhanced joystick ports (EJP) were added (two normal joysticks could be plugged into each port with an adaptor), with the new connectors placed in more easily-accessed locations on the side of the case. The enhanced joystick ports were re-used in Atari’s Jaguar console, and are compatible. RAM was now much more simply upgradable via SIMMs. Despite all of this, it still ran at 8 MHz.

Atari STe: More Or Less Zero by Dead Hackers Society on real Hardware.

source: wikipedia

Gallery:

The PETdisk is a new storage device, made by bitfixer, for the Commodore CBM / PET with an IEEE-488 port.

The system is in two parts. A datassette module that makes it possible to play “data” from a PC soundcard to the CBM / PET and play “data” from the CBM / PET to the PC. The IEEE-488 module has an SD card and a micro processor.

You can use the commands LOAD, SAVE and LOAD “$” to load or store data on the SD card. The device number can be changed with a help of a jumper. The USB cable is used to provide 5VDC from the datassette module to the IEEE-488 module.

For more informations,schematics,documentations and price of the kit please visit the site of the author.

Video demostration:

source: bitfixer.com

Autopsy:

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The Commodore PET 2001-N (the N was short for “New”) is a successor to the Commodore PET 2001, it has a bigger keyboard and 32KB dynamic RAM memory. The larger keyboard means that the first cassette drive now has to be an external unit.

from Wikipedia:

The Commodore PET (Personal Electronic Transactor) was a home/personal computer produced from 1977 by Commodore International. A top-seller in the Canadian and United States educational markets, it was Commodore’s first full-featured computer, and formed the basis for their entire 8-bit product line.

The PET 2001 was announced at the Winter CES in January 1977 and the first 100 units were shipped later that year in October. However, the PET was back-ordered for months and to ease deliveries, early in 1978 Commodore decided to cancel the 4 kB version (also because the user would be left with barely 3 kB of RAM).

Although the machine was fairly successful, there were frequent complaints about the tiny calculator-like keyboard, often referred to as a “chiclet keyboard” because the keys resembled the gum candy. The key tops also tended to rub off easily. Reliability was fairly poor, although that was not atypical of many early microcomputers. Because of the poor keyboard on the PET, external replacement ones quickly appeared.

In 1979, Commodore replaced the original PET 2001 with an improved model known as the 2001-N (the N was short for “New”). The new machine used a standard green-phosphor monitor in place of the light blue in the original 2001. It now had a conventional, full-sized keyboard and no longer sported the built-in cassette recorder. The kernel ROM was upgraded to add support for Commodore’s newly-introduced disk drive line. It was offered in 8kB, 16kB, or 32kB models as the 2001-N8, 2001-N16, and 2001-N32 (the 8kB models were dropped soon after introduction). Finally, Commodore added a machine-language monitor to the kernel ROM that could be accessed by jumping to any memory location with a BRK instruction. It did not include a built-in assembler and required the user to enter hexadecimal numbers for coding.

Sales of the newer machines were strong, and Commodore then introduced the models to Europe. The result was the CBM 3000 series (‘CBM’ standing for Commodore Business Machines), which included the 3008, 3016 and 3032 models. Like the 2001-N-8, the 3008 was quickly dropped. The change to CBM occurred because of a trademark dispute with Philips over the PET name.

source: wikipedia

Autopsy:

from Wikipedia:

The Power Mac G4 was a series of personal computers that was designed, manufactured, and sold by Apple between 1999 and 2004.

They used the PowerPC G4 (PPC74xx) series of microprocessors. They were heralded by Apple to be the first personal supercomputers, reaching speeds of 4 to 20 Gigaflops. They were both the last Macintoshes to boot natively into Classic Mac OS and the first to boot exclusively into Mac OS X.

The original Apple Power Mac G4, code name “Yikes!”, was introduced at the Seybold conference in San Francisco on August 31, 1999, with 400 MHz, 450 MHz and 500 MHz configurations available. In October 1999, Apple was forced to postpone the 500 MHz because of poor yield of the 500 MHz chips. In response, Apple “speed dumped” the processor speed in each configuration by 50 MHz but caused some controversy by not decreasing the price of the machines.

Another generation of Apple Power Mac G4s were introduced on August 13, 2002, featuring both a new Xserve-derived DDR motherboard architecture and a new case design, known as “Mirrored Drive Doors” (MDD). All models were available in dual processor configurations running at 867 MHz, 1 GHz or 1.25 GHz. As with the Xserves, the PowerPC 7455 CPU used does not have a DDR frontside bus, meaning the CPU could only use at most 50% of the new system’s theoretical memory bandwidth, providing no improvement over previous models. The rest was available to the graphics card and I/O systems. A dual processor 1.25 GHz model would be the last Power Mac G4 the company offered to the public after the announcement of the new Power Mac G5, introduced in June 2003.

source: wikipedia

This is the story of a Commodore CBM (PET) 3032 recovered in a pitiful state.

The motherboard was covered of rust and many IC are in short circuit. I had to replace some IC (broken or full of rust), rebuild some paths of the pcb and clean very well.

I have also restored the inside of the case, using an anti-rust gel painting.

Photos and Description of the work made:

Read more…

Autopsy:

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The Commodore CBM (PET) 3032 is a successor to the Commodore PET 2001, it has a bigger keyboard and 32KB dynamic RAM memory. The larger keyboard means that the first cassette drive now has to be an external unit.

from Wikipedia:

The Commodore PET (Personal Electronic Transactor) was a home/personal computer produced from 1977 by Commodore International. A top-seller in the Canadian and United States educational markets, it was Commodore’s first full-featured computer, and formed the basis for their entire 8-bit product line.

The PET 2001 was announced at the Winter CES in January 1977 and the first 100 units were shipped later that year in October. However, the PET was back-ordered for months and to ease deliveries, early in 1978 Commodore decided to cancel the 4 kB version (also because the user would be left with barely 3 kB of RAM).

Although the machine was fairly successful, there were frequent complaints about the tiny calculator-like keyboard, often referred to as a “chiclet keyboard” because the keys resembled the gum candy. The key tops also tended to rub off easily. Reliability was fairly poor, although that was not atypical of many early microcomputers. Because of the poor keyboard on the PET, external replacement ones quickly appeared.

In 1979, Commodore replaced the original PET 2001 with an improved model known as the 2001-N (the N was short for “New”). The new machine used a standard green-phosphor monitor in place of the light blue in the original 2001. It now had a conventional, full-sized keyboard and no longer sported the built-in cassette recorder. The kernel ROM was upgraded to add support for Commodore’s newly-introduced disk drive line. It was offered in 8kB, 16kB, or 32kB models as the 2001-N8, 2001-N16, and 2001-N32 (the 8kB models were dropped soon after introduction). Finally, Commodore added a machine-language monitor to the kernel ROM that could be accessed by jumping to any memory location with a BRK instruction. It did not include a built-in assembler and required the user to enter hexadecimal numbers for coding.

Sales of the newer machines were strong, and Commodore then introduced the models to Europe. The result was the CBM 3000 series (‘CBM’ standing for Commodore Business Machines), which included the 3008, 3016 and 3032 models. Like the 2001-N-8, the 3008 was quickly dropped. The change to CBM occurred because of a trademark dispute with Philips over the PET name.

source: wikipedia

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This is a Video RGB Hack for the console Sega SG-1000 II (Mark 2).

The Sega 315-5066 Video Chip inside the Sega SG-1000 II (Mark 2) used in the latest version of the console uses two video output formats: NTSC Composite video (converted to RF), and RGB (not connected).

The RGB Video is the stuff from which all other formats are born. Once your RGB is tapped it can be easily converted to Component or S-video, giving stunning output far superior to what the Sega SG-1000 II natively offers (only RF).

There are several caveats, of course. The biggest is the quality of the RGB output – it’s not very bright, and will result in an image without much contrast, so you will probably need to add an amplifier. Even on monitors that display a very good image without the amp you’ll sometimes find the sync signal needs an amp to generate a stable image.

I have used the same RGB/Sync Amplifier used on the PC-Engine, components and the Original schematic are shown below.

Schematic:

Components:

• 4 x 2SC1815 (Transistor)
• 4 x 220 μF 16v (Electrolytic capacitor)
• 4 x 10 μF 16v (Electrolytic capacitor)
• 4 x 75 Ω (Resistor)
• 8 x 10 KΩ (Resistor)
• 1 x 300 Ω (Resistor)

The three photos below show the connection between the RGB Amplifier and the PCB of the Sega SG-1000 II.

Autopsy:

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TODO: Modify the console to support RGB output. When is ready i’m going to post the project.

from Wikipedia:

The SG-1000 (エスジー・セン Esujī Sen?), which stands for Sega Game 1000, was a cartridge-based video game console manufactured by Sega. This system marked Sega’s first entry into the home video game hardware business, and while the system was not popular, it provided the basis for the more successful Sega Master System.

The SG-1000 was first released to the Japanese market on July 15, 1983. Coincidentally, this is exactly the day that Nintendo’s Family Computer was released in Japan. The console reached minor success in that market and sold moderately well within Asia until 1985. The system was launched in New Zealand as released by Grandstand Leisure Limited, Australia by John Sands and in other countries, such as France, Italy, Spain, and South Africa. The console in its original form was never launched in North America.

In July 1984, Sega released an updated version of the console called the SG-1000 II. It is functionally identical to the SG-1000, but has a re-styled shell and the connector for the optional plug-in SK-1100 keyboard has been moved from the rear to the front. It was initially priced at ¥15,000. A computer version of this console, with a built-in keyboard, was called the SC-3000, which would go on to outsell the SG-1000.

The SG-1000 runs all SC-3000 games and applications, with the exception of Music and Basic Cartridges. The machine could be used just like the SC-3000, provided one had the keyboard attachment ready. In Japan the console also had an optional game card reader add-on called the Card Catcher that allowed for the use of Sega game card software. Card based software was exclusive to Japan, only cartridge based games were released in Europe and Oceania.

The Card Catcher would become built into the Sega Mark III, as well as the first version of the Master System.

source: wikipedia

Autopsy:

from Wikipedia:

Techno Source was one of the pioneers of the ‘retro gaming’ market, creating TV Game systems that plug directly into your TV. Their products were one of the reasons for the increased “popularity of these devices from a 30 million dollar industry 4–5 years ago to over 500 million dollars” today.

After entering into a licensing partnership with Intellivision in 2003, Techno Source introduced the Intellivision 25, which features 25 original Intellivision games in one plug-and-play unit. With the success of the Intellivision 25 and its follow-up, the Intellivision 10, Techno Source sold over 1,000,000 units and received the National Parenting Center Seal of Approval in 2004.

This line now includes the 2-player Intellivision X2 and the Intellivision 10 2nd Edition. According to the Blue Sky Rangers, the original programmers of the Intellivision games, Techno Source has sold more Intellivision games today than Mattel Electronics originally sold in the 1980s.

source: wikipedia

Autopsy:

Cabletronic ESP 329 is a 2 MB Fast RAM expansion for Amiga 500/1000 (no passthrough port).

source: amiga.resource.cx