These two computers had the classic fault: Black screen of Death.

The first one was repaired by replacing a ram chip (4264) partially interrupted, the other one had One of the two chip PLA dead.

I have to thank my friend Andrea for providing me a motherboard of a 8296 for spare parts, where i have recovered the PLA which i needed.

Autopsy:

from CPCWiki:

The Amstrad (Schneider) CTM640/CTM644 are two colour monitors sold together with the classic CPC-computers. Optionally, the computer could have been purchased with GT64/GT65 green monitors. The only difference between the CTM640 and CTM644 models is the additional 12V power supply for the CPC664/CPC6128′s disk drive in the later model.

With the arrival of the CPC664 and CPC6128 models, the existing stock of CTM640 monitors was sold out and later only CTM644 monitors were sold, even with the CPC464. For that reason, the 12V power outlet was designed as a socket for a cable coming from the CPC, while all other connections were made with cables coming from the monitor.

Amstrad (Schneider) Colour Monitor CTM 644 demostration:

source: cpcwiki.eu

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.

Photo of the repair:

The 8250LP Floppy Drive is arrived with the following faults:

• The main motor of the Floppy Drive D0 spins only for a couple of seconds and then stops.
• The Floppy Drive D1 have a problem of the hinge for the disk pressure.

About the problem of the motor of Drive D0 have been replaced a voltage regulator 7812 and an electrolytic capacitor in losses. The mechanics of the Drive D1 was repaired using the Loctite.

source: wikipedia

The HxC Floppy Drive Emulator is a software and hardware system created by jfdn aka Jeff.

The aim of this project is to replace the floppy disk drive by an electronic device emulating the floppy disk drive (list of supported Computer/Hardware).

There are two differents emulators:

• A USB version which allows to connect the floppy disk drive interface of the computer to a PC via a USB cable.
• A SDCARD version which allows to emulate floppy disks which images are stored in a SDCARD.

Changelog SD HxCFloppyEmulator v1.8.2.36 (fat) & v2.1.2.36 (slim):

• Write Support : Write issue with VIA VT82C686A chipset based motherboard corrected.

Download:

• HxC Floppy Emulator Firmware v1.8.2.36 (1009)
• Slim HxC Floppy Emulator Firmware v2.1.2.36 (955)

source: hxc2001.free.fr

Sorry, this entry is only available in Italian.

SNDH archive v4.2 released - 3921 SNDH files (total 7389 tunes)

Ever since the birth of the Atari ST, different chip music formats have had different ways to use them. If you are coding a chip music player for the Atari ST you would have to use dozens and dozens of special ways to replay music.

But in the mid 90′s, BDC of Aura crew became tired of this inelegant system and decided to fix the issue once and for all. He then created the ‘SNDH’ file format. SNDH is actually the original songfile and replaycode with a header bolted on top of the music and replayer. The header has a unified calling interface no matter what type of chip music is hidden beneath it, and it has extended datas about the music.

Download: SNDH Atari ST YM2149 Archive v4.2 (1458)

source: sndh.atari.org

CBM prg Studio Version 2.8.0 is released. There are a lot of new features in this version. I’d really appreciate it if you report any bugs you find or have any suggestions/comments.

CBM prg Studio allows you to type a BASIC or Machine Code program in using a nice Windows environment and convert it to a ‘.prg’ file which you can run on an emulator, or even a real C64 / VIC20 or PET if you’re feeling brave and have the right kit.

CBM prg Studio is the result of merging C64PrgGen and VIC20PrgGen. Adding new features and fixing bugs in two apps which were 95% similar was a bit of a nightmare so merging them made sense.

It was also a good opportunity for a face lift and to add some new features, such as:

• Programs are project based, meaning all related source files, sprite files etc. are kept in one place and multiple source files can be linked more easily.
• Tabbed MDI.
• Syntax highlighting.

What CBM prg Studio isn’t is a front-end for tok64, cbmcnvrt, bastext or any other tokeniser / detokeniser / assembler. It’s all been written completely from scratch.

New features:

• Screen RAM viewer for debugger.
• Ignore/truncate REM statements during code generation switch.
• Project comments.
• The character editor’s scratch pad can be imported to the screen editor.
• Save/load configuration settings.
• Import multicolour bitmaps into the sprite editor.
• Export binary files from the character editor.
• Much improved BASIC and assembly generation time.

See the help for a complete list of bug fixed.

Download: CBM prg Studio v2.8.0 (952)

source: ajordison.co.uk

Sorry, this entry is only available in Italian.

Autopsy:

Here you can see a hack of my dtv (Direct-to-TV).

from Wikipedia:

The C64 Direct-to-TV, called C64DTV for short, is a single-chip implementation of the Commodore 64 computer, contained in a joystick (modeled after the mid 1980s Competition Pro joystick) with 30 built-in games. The design is similar to the Atari Classics 10-in-1 TV Game. The circuitry of the C64DTV was designed by Jeri Ellsworth, a self-taught computer chip designer who had formerly designed the C-One.

Tulip Computers (which had acquired the Commodore brand name in 1997) licensed the rights to Ironstone Partners, which cooperated with DC Studios, Mammoth Toys, and “The Toy:Lobster Company” in the development and marketing of the unit.[1] QVC purchased the entire first production run of 250,000 units and sold 70,000 of them the first day they were offered.

There exist multiple versions of the C64DTV. DTV1 (NTSC television type) comes with 2 MB ROM. It first appeared in late 2004 for the American/Canadian market. DTV2 (called C64D2TV sometimes) is a revised version for the European and world markets (PAL television type) and appeared in late 2005. The ROM has been replaced by flash memory in these devices. However, the DTV2/PAL version suffers from a manufacturing fault, which results in poor colour rendering (the resistors in the R-2R ladder DACs for both the chroma and the luma have been transposed). In the DTV3, a problem with the blitter was fixed. Another DTV variant is the Radio Shack “HUMMER Off-Road Racing Challenge Video Game”.

Hardware Specifications:

Core circuity:

• ASIC running at 32 MHz internally, implementing 6510 CPU, VIC-II, SID, CIA, and PLA

Casing/Connectors:

• Integrated in a Joystick (as if connected to port 2 of a real C64)
• Five additional buttons (acting like keys)
• Running from batteries only (four AA batteries)
• Composite Video, monaural audio (RCA connectors)
• Looks similar to a Competition Pro joystick

Graphics:

• NTSC (DTV2 and later: NTSC/PAL on chip, only PAL wired in end-market devices)
• Reprogrammable palette with 4 bits of luma and 4 bits of chroma
• DTV2 and later: “chunky” 256 color mode, additional blitter for fast image transformation

Sound:

• No support for SID filters
• DTV2 and later: 8 bit digital sound, additional options for envelope generators

Memory:   

• DTV1: 128 KB RAM, 2 MB ROM
• DTV2 and later: 2 MB RAM, 2 MB flash memory
• DMA engine for RAM/RAM and ROM/RAM transfers
• DTV2 and later: additional RAM access using bank switching and blitter

CPU:

• Implementing a 6510 at 1 MHz
• DTV2 and later: Enhanced CPU (fast/burst mode, additional registers and opcodes, support for illegal ops of the 6510)

source: wikipedia dtvhacking.retrosafe.com

Autopsy:

The Expandamem of CompuThink (Compu/Think) is a Memory expansion card for Commodore PET (chicklet keyboard) and KIM-1.

The memory expansion was installed inside the Computer Commodore PET and with a particular hook was fixed above the motherboard. The connection was through the expansion bus and a power connector.

Download: CompuThink Memory Expansion Manual (1607)

Autopsy:

The Analog Joystick by Pico Products is a compatible Joystick with Apple and IBM AT/XT PC.

Specifications:

• Quickfire button on sitck.
• User Selectable Auto-Centering or Free-Floating Operating Modes.
• Right and Left hand function with firing Buttons.
• Dual Axis Vatiable Resistor Controls for Accurate and Stable Cursor control.
• Apple II,II+,IIc,IIgs and IBM PC,AT,XT compatible.

I thank a friend for the donation.

Donated items:

• Hardital (Italy) Bang 2082.
  • This is a Accelerator expansion for Amiga 500/2000 with a 68020 @ 14.3 MHz (synchronous) and a optional FPU up to 68882 @ 25 MHz (asynchronous).

• Logica (Italy) Kick Mouse.
  • Kickstart Switcher 2.0

Autopsy:

from Zimmers homepage:

The Commodore 1600 was an extremely prolific and inexpensive modem, introducing millions of computer users to the online world. Marketed to the VIC-20 user, the “VICMODEM” as it was nicnamed, operated in an extremely strange manner.

Instead of connecting to the phone line directly, the VICMODEM relied on a connection THROUGH the phone to the handset. One would dial the number they wished to connect to, then remove the extension from their handset, plugging it into the modem after a carrier signal is heard.

Some customers in Canada were lucky enough to get their VICMODEM packaged with this telephone manufactured in Canada by Northern Telecom. Ironically, the phone did not have a detachable handset, making it useless by itself for use with the modem. Therefore, the set also included a small adaptor which allowed one to plug the VICMODEM directly into the wall line cable, daisy chained to the phone. After dialing with the phone, a switch on the adaptor would redirect the carrier signal to the modem.

Download: Commodore VIC Modem Model 1600 Manual (1642)

source: zimmers.net

Autopsy:

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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.

Cleaning / Replacement of the little rubber, reconstruction of pitches with a soft pencil:

source: wikipedia cpcwiki.eu

The composite video mod for the computer Microdigital TK-83 unlike the Sinclair ZX81 it’s more easier.

You no need to install the usual transistor with 1 or 2 resistors / capacitor. The transistor is already installed on the motherboard of the Microdigital TK-83, so just pick up the video signal as described in the picture.

I remind you that the output signal will be in NTSC standard for the Microdigital TK-83 produced in Brazil (PAL-M)