Autopsy:

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from Wikipedia:

The Commodore 8050 and Commodore 8250 were dual unit 5¼” floppy disk drives for Commodore International computers. They used a wide rectangular steel case form similar to that of the Commodore 4040, and used the IEEE-488 interface common to Commodore PET/CBM computers.

The 8050 was a single sided drive, whereas the 8250 could use both sides of a disk simultaneously. Both used a “quad” density format storing approximately 0.5 megabyte per side. The density of media was similar to later PC high density floppy disks, but the 8050 and 8250 could not use PC high density disks reliably. Since “quad” density disks were rare even at the time, users quickly found that typical double density floppy disks had enough magnetic media density to work in these drives.

These drives were not dual mode, so they could not read or write disks formatted by the more common lower capacity Commodore 1541 or Commodore 4040 models. Some variants of these drives existed. The Commodore 8250LP was the 8250 in a lower profile, tan-colored case. The Commodore SFD-1001 was a single drive version of the 8250 in a Commodore 1541 style case (similarly to the Commodore 2031LP), often used by bulletin board systems for their physical similarity to 1541s and high capacity and speed.

source: wikipedia

Autopsy:

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The RGB cable of  Schneider (radiola/philips) VG-5000 computer is compatible with the VideoPac G7200.

from Wikipedia:

The Magnavox Odyssey², known in Europe as the Philips Videopac G7000, in Brazil as the Philips Odyssey, in the United States as the Magnavox Odyssey² and the Philips Odyssey², and also by many other names, is a video game console released in 1978.

In the early 1970s, Magnavox was an innovator in the home video game industry. They succeeded in bringing the first home video game system to market, the Odyssey, which was quickly followed by a number of later models, each with a few technological improvements (Magnavox Odyssey Series). In 1978, Magnavox, now a subsidiary of North American Philips, released the Odyssey², its new second-generation video game console.

In Europe, the Odyssey² did very well on the market. In Europe, the console was most widely known as the Philips Videopac G7000, or just the Videopac, although branded variants were released in some areas of Europe under the names Philips Videopac C52, Radiola Jet 25, Schneider 7000, and Siera G7000. Philips, as Magnavox’s Dutch parent company, used their own name rather than Magnavox’s for European marketing. A rare model, the Philips Videopac G7200, was only released in Europe; it had a built-in black-and-white monitor. Videopac game cartridges are mostly compatible with American Odyssey² units, although some games have color differences and a few are completely incompatible. A number of additional games were released in Europe that never came out in the US.

Download: Philips VideoPac G7200 Schematics (1453)

Playing Munchkin game:

source: wikipedia

I have decided to repair my two ColecoVision consoles bought like non-functioning many years ago. Below a description of the defects and of components being replaced.

Defect: black screen

• 1 x 2114 (VRAM)
• Joystick port # 1 broken (replaced with the joystick port of a Texas Instruments TI-99/4A)

Defect: black screen

• 1 x 2114 (VRAM)
• 3 x 4116 (RAM)

How to write the .DSK files to Floppy Disk for the Sharp MZ-80B ?

The answer is quite simple, first of all there you need an old computer with harddisk with installed the operating system DOS/FreeDOS and a Floppy Drive 5¼. The tool to use is the CPDWrite (Copy Protected Disk Writer) v1.03 and some floppy disk image in .DSK format for the Sharp MZ-80B.

Below you can download the archive containing many floppy disk in .DSK format and the utility to write files on Floppy Disk.

The original archive was downloaded from this web page, but unfortunately the only one floppy disk that seemed to be more interesting ‘DISK15.DSK’ containing the games for this computer was corrupted. I found the problem and i have fixed with the use of a hex editor, the fixed version was included in the archive.

Download:

• CPDWrite v1.03 (1364)
• MZ-80B (DSK) Floppy Images (1390)

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from Wikipedia:

The Sharp MZ is a series of personal computers sold in Japan and Europe (particularly Germany and Great Britain) by Sharp beginning in 1978.

Although commonly believed to stand for “Microcomputer Z80″, the term MZ actually has its roots in the MZ-40K, a home computer kit produced by Sharp in 1978 which was based on Fujitsu’s 4-bit MB8843 processor and provided a simple hexadecimal keypad for input. This was soon followed by the MZ-80K, K2, C, and K2E, all of which were based on 8-bit LH0080A Sharp CPU (compatible to Zilog Z80A) with an alphanumeric keyboard.

From the first Z80 processor-based model to the MZ-2200 in 1983, the MZ computers included the PC, monitor, keyboard, and tape-based recorder in a single unit, similar to Commodore’s PET series. It was also notable for not including a programming language or operating system in ROM, like the IBM PC. This allowed a host of third-party companies, starting with Hudson Soft, to produce many languages and OSes for the system. In an era when floppy disk drives were too expensive for most home users, the MZ’s built-in tape drive was considered faster and more reliable than the drive on competing computers; however, this meant that the MZ series was relatively slow to adopt floppy drives as a standard accessory.

The MZ series is divided into several lines, including the text-based MZ-80K series, the graphics-based MZ-80B series, and the MZ-3500/5500 series, based on a completely different architecture. In 1982, Sharp’s television division released the X1, a completely new computer. The X series proved to outsell Sharp’s own MZ series, and in response, Sharp released the MZ-1500/2500 machines, which featured powered-up graphics and sound capabilities. However, this series saw little marketplace success, and eventually the company abandoned the line in favor of the X68000 series.

The MZ name lives on as the initials of two of Sharp’s most well-known products: the Mebius line of PCs, and the Zaurus line of personal digital assistants.

Sharp MZ-80B Loading Basic from Disk Drive CE 510:

source: wikipedia

We must always remember to remove the filter capacitor RIFA before turning on a computer off for over 30 years. Otherwise it might happen that you can see from the photos and the video.

This time is my fault because i had completely forgotten.

The Magic Smoke of a RIFA capacitor:

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Commodore CBM 8032 fully functional but without Monitor donated by Andrea Pierdomenico.

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I have received to repair five TI-99/4A with the following defects:

1. Black Screen
2. Working but with some dirt on the screen.
3. Vertical Stripes moving with a deafening sound.
4. Blue Screen with thin vertical stripes and deafening sound.
5. Blue Screen with thin vertical stripes and deafening sound.

The first two are repaired with the following faults:

Black Screen Fault: replaced TMS9929A followed by ROM CD2156NL
Dirt on the screen: replaced a 4116 RAM.

The third motherboard was used for spare parts.

The fourth and fifth motherboard with the blue screen have been the most annoying.

I spent 6 + hours to make measurements with an oscilloscope comparing one of the two motherboards with a working one to find the fault but the signals/voltages were absolutely identical.

So i have decided to go for exclusion and with a TI-99/4A Tech Data manual on my hand and 39.5 degrees in my Laboratory i have started to desolder and put a socket of the following components:

• 1 x TMS9901NL (20 +20 PIN)
• 1 x TMS9900NL (32 +32 PIN)
• 1 x TIM9904NL (10 +10 PIN)
• 1 x TMS 4732/2532 ROM U610 (12 +12 PIN)
• 1 x TMS 4732/2532 ROM U611 (12 +12 PIN)
• 1 x 74LS244 (10 +10 PIN)
• 1 x 74LS245 (10 +10 PIN)
• 1 x 74LS373 (10 +10 PIN)
• 1 x 74LS03 (7 +7 PIN)
• 1 x 74LS138 (8 +8 PIN)
• 1 x 74LS74 (7 +6 PIN)
• 1 x 4116 (8 +8 PIN)

After all this work nothing had changed, nothing worked, always BLUE screen.

I redid the measurements, but nothing, everything looked the same.

At this point there are only two static memories MCM6810P but that i don’t have investigated for what are used, because already on the motherboard are 8 x 4116 RAM Memory shared between Memory program and Video memory.

… anyway … i have tried to unsolder and put a socket.

So we add:

• 2 x MCM6810P (12 +12 PIN)

Et Voilà the two MCM6810P are both dead! both!

Obviously i don’t have this component in my laboratory, then i try to recover from the motherboard for spare these two RAM hoping that they are not faulty which however these RAM can be purchased online at a very low price.

The fifth and last motherboard that had the same defect of the previous one did not have the faulty ram MCM6810P.

To repair i had to replace the following components:

• 1 x 74LS04 (7 +7 PIN)
• 1 x TMS9900NL (32 +32 PIN)

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from Wikipedia:

The Texas Instruments TI-99/4A was an early home computer, released in June 1981, originally at a price of US$525. It was an enhanced version of the less successful TI-99/4 model, which was released in late 1979 at a price of $1,150. The TI-99/4A added an additional graphics mode, “lowercase” characters consisting of small capitals, and a full travel keyboard. Its predecessor, the TI-99/4, featured a calculator-style chiclet keyboard and a character set that lacked lowercase text.

The TI-99/4A’s CPU, motherboard, and ROM cartridge (“Solid State Software”) slot were built into a single console, along with the keyboard. The power regulator board is housed below and in front of the cartridge slot under the sloped area to the right of the keyboard. This area gets very hot so users commonly refer to it as the “coffee cup warmer”. The external power supply, which was different according to the country of sale, was merely a step-down transformer.

Available peripherals included a 5¼” floppy disk drive and controller, an RS-232 card comprising two serial ports and one parallel port, a P-code card for Pascal support, a thermal printer, an acoustic coupler, a tape drive using standard audio cassettes as media, and a 32 KB memory expansion card. The TI-99/4 was sold with both the computer and a monitor (a modified 13″ Zenith Color TV) as Texas Instruments could not get their RF Modulator FCC approved in time. The TI-99/4A did ship with an RF Modulator.

In the early 1980s, TI was known as a pioneer in speech synthesis, and a highly popular plug-in speech synthesizer module was available for the TI-99/4 and 4A. Speech synthesizers were offered free with the purchase of a number of cartridges and were used by many TI-written video games (notable titles offered with speech during this promotion were Alpiner and Parsec). The synthesizer used a variant of linear predictive coding and had a small in-built vocabulary. The original intent was to release small cartridges that plugged directly into the synthesizer unit, which would increase the device’s built in vocabulary. However, the success of software text-to-speech in the Terminal Emulator II cartridge cancelled that plan. Most speech synthesizers were still shipped with the door that opened on the top, although very few had the connector inside. There are no known speech modules in existence for those few units with the connector. In many games (mostly those produced by TI), the speech synthesizer had relatively realistic voices. For example, Alpiner’s speech included male and female voices and could be quite sarcastic when the player made a bad move.

Playing Alpiner Cartridge:

source: wikipedia

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I had to build the power cable (8.5 – 10 volts), video Composite output and In/Out tape, because was not given with the computer as standard.

from Wikipedia:

MicroBee (Micro Bee) was a series of home computers by Applied Technology, later known as MicroBee Systems.

The original MicroBee computer was designed in Australia by a team including Owen Hill and Matthew Starr. It was based on features available on the DG-Z80 and DG-640 S-100 cards developed by David Griffiths, TCT-PCG S-100 card developed by TCT Micro Design and MW6545 S-100 card developed by Dr John Wilmshurst. It was originally packaged as a two board unit, with the lower “main board” containing the keyboard, Zilog Z80 microprocessor, Synertek 6545 CRT controller, 2 kB of “screen” RAM, 2 kB of character ROM (128 characters) and 2 kB of Programmable Character Graphics (PCG) RAM (128 characters). Each byte in the screen RAM addressed a character in either the character ROM or PCG RAM. A second board, termed the “core board”, contained the memory, and on later models also included a floppy disk controller.

The computer was conceived as a kit, with assembly instructions included in Your Computer magazine, in June 1982. After a successful bid for the New South Wales Department of Education computer tender, the computer was repackaged in a two-tone beige and black case, and sold pre-built. The 16 kB ROM held the MicroWorld BASIC interpreter written by Matthew Starr and DGOS (David Griffiths Operating System) compatible System Monitor. In addition to the 16 kB ROM, there is additional ROM socket for optional programs such as WORDBEE (Word processor) or EDASM (a Z80 Editor/Assembler that was written by Ron Harris).

Original MicroBees ran at a clock speed of 2 MHz, with a video dot clock of 12 MHz, which was sufficient to display 64 × 16 characters (512 × 256 pixels) on a modified television or composite monitor. The original machines were supplied with 16 or 32 kB of static RAM, and stored programs on cassette, using 1200 Baud encoding.

source: wikipedia

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I have repaired the PSU with the failure of stanby mode of the Sharp X68000 (gray version). The failure was caused by two electrolytic capacitors and the voltage regulator 7805 in short circuit.

I have also tried to repair the external case of the Sharp X68000 (gray version) that during the first transport in Italy many years ago was destroyed.

from Wikipedia:

The Sharp X68000, often referred to as the X68k, is a home computer released only in Japan by the Sharp Corporation. The first model was released in 1987, with a 10 MHz Motorola 68000 CPU (hence the name), 1 MB of RAM and no hard drive; the last model was released in 1993 with a 25 MHz Motorola 68030 CPU, 4 MB of RAM and optional 80 MB SCSI hard drive. RAM in these systems is expandable to 12 MB, though most games and applications did not require more than two.

The X68k ran an operating system developed for Sharp by Hudson Soft, called Human68k, which features commands very similar to those in MS-DOS (typed in English). Pre-2.0 versions of the OS had command line output only for common utilities like “format” and “switch”, while later versions included forms-based versions of these utilities, greatly improving their usability. At least three major versions of the OS were released, with several updates in between. Other operating systems available include NetBSD for X68030 and OS-9.

Early models had a GUI called “VS” (Visual Shell); later ones were packaged with SX-WINDOW. A third GUI called Ko-Windows existed; its interface is similar to Motif. These GUI shells could be booted from floppy disk or the system’s hard drive. Most games also booted and ran from floppy disk; some were hard disk installable and others require hard disk installation.

Since the system’s release, Human68k, console, and SX-Window C compiler suites and BIOS ROMs have been released as public domain and are freely available for download.

Early machines use the rare Shugart Associates System Interface (SASI) for the hard disk interface; later versions adopted the industry-standard small computer system interface (SCSI). Per the hardware’s capability, formatted SASI drives can be 10, 20 or 30 MB in size and can be logically partitioned as well. Floppy disks came in a couple of different formats, none of which are natively readable on other platforms, although software exists that can read and write these disks on a DOS or Windows 98 PC.

source: wikipedia

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I have built a cable from 6-DIN to VGA to use this computer with a Monitor VGA Multisync (15khz)

from Wikipedia:

The X1 is a series of home computer released by Sharp Corporation from 1982 to 1988. It was based on a Z80 CPU.

Despite the fact that the Computer Division of Sharp Corporation had released the MZ series, suddenly the Television Division released a new computer series called the X1. At the time the original X1 was released, all other home computers generally had a BASIC language in ROM. However the X1 did not have a BASIC ROM, and it had to load the Hu-BASIC interpreter from a cassette tape. On the plus side however, this concept meant that a free RAM area was available that was as big as possible when not using BASIC. This policy was originally copied from the Sharp MZ series, and they were called clean computers in Japan. The cabinet shape of X1 was also much more stylish than others at that time and a range of cabinet colors (including Red) was selectable.

The RGB display monitor for the X1 had a television tuner, and a computer screen could be super-imposed on TV. All the TV functions could be controlled from a computer program. The character font was completely programmable (A.K.A. PCG) with 4bit color, and it was effectively used into a lot of games. The entirety of the VRAM memory was mapped on to the I/O area, so it was controlled without bank change. Since X1 had these features, it was very powerful for game software.

While X1 was struggling to sell, the PC8801 (from NEC) was quickly becoming popular in the Japanese market. In 1984, Sharp released the X1 turbo series with high resolution graphics (640×400, while X1 had 640×200). It had a lot of improvements, but the clock speed was still only 4 MHz. In 1986, Sharp released the X1 turbo Z series with a 4096 color analog RGB monitor. An X1 twin, which had a PC-Engine in the cabinet, was finally released as the last machine of the X1 series in 1987. Then this series was succeeded by the X68000 series.

Sharp continues to sell desktop PC/TV combos in Japan through its Internet Aquos line, where an X1-style red color scheme is available.

Download: Sharp X1 (CZ-812CR) Rom (1401)

source: wikipedia

I ran the repair of the membrane that had a micro interruption, i have used a micro-drop of vinilic glue mixed with the graphite that i have scraped from the pencil ikea, i made a thin film on the microfracture and now it works.

There were other problems, including: graphite consumed in some keys and the keyboard connector (pcb side) don’t work very well.

Autopsy:

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The horrible holes for the switch and the button are used to halt the CPU and RESET.

from Wikipedia:

The Amstrad CPC (short for Colour Personal Computer) is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the Sinclair ZX Spectrum, where it successfully established itself primarily in the United Kingdom, France, Spain, and the German-speaking parts of Europe.

The series spawned a total of six distinct models: The CPC464, CPC664, and CPC6128 were highly successful competitors in the European home computer market. The later plus models, 464plus and 6128plus, efforts to prolong the system’s lifecycle with hardware updates, were considerably less successful, as was the attempt to repackage the plus hardware into a game console as the GX4000.

The CPC models’ hardware is based on the Zilog Z80A CPU, complemented with either 64 or 128 kB of memory. Their computer-in-a-keyboard design prominently features an integrated storage device, either a compact cassette deck or 3″ floppy disk drive. The main units were only sold bundled with a colour or monochrome monitor that doubles as the main unit’s power supply. Additionally, a wide range of first and third party hardware extensions such as external disk drives, printers, and memory extensions, was available.

The CPC series was pitched against other home computers primarily used to play video games and enjoyed a strong supply of game software. The comparatively low price for a complete computer system with dedicated monitor, its high resolution monochrome text and graphic capabilities and the possibility to run CP/M software also rendered the system attractive for business users, which was reflected by a wide selection of application software.

During its lifetime, the CPC series sold approximately three million units.

source: wikipedia

I have received this motherboard of a CBM 8032 to repair from Rossano T.

The motherboard was devastated by rust, many components are short-circuited due to rust that was abundant on the pins side of the chip. Unfortunately the computer was turned on to test it, causing the total breakdown of more components.

I have installed 40 socket because some components are rusty other are dead, however some traces under the chips are eaten by rust and and i had to rebuild.

The repair and cleaning took me a very long time and a lot of patience, it took me about 10+ hours.

Components Replaced:

• 1 x 4650 (6845P) CRT Controller
• 3 x 4116 RAM
• 2 x 2114 Video RAM
• 5 x 74LS244
• 3 x 74LS74
• 1 x 74LS02
• 1 x 1uf 100v Capacitor

Phases of the repair:

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