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Restoration and Repair of a Sinclair Spectrum 128k +2A Arabic Version

August 11th, 2013 4 comments
Sinclair Spectrum 128k +2A (Black) Arabic Version

Autopsy:

This is the translation of the Arabic boot screen:

© 1987, 1988 Sinclair of Egypt
presented by Matsico Corp, an authorized dealer of Sinclair & Amstrad in Egypt
prepared by Dr. Nabil Nazmi
(Version 3)

The computer is arrived in pitiful condition. The inside of the computer and the keyboard were are full of sand and dirt.

Restoration and repairs that have been made:

  • Replaced the top case with a new one.
  • Replaced the bottom case with a new one, then replaced again with the old one to keep the original appearance. (the hole for the switch is standard in the Arabic version)
  • Replaced the tape recorder.
  • Replaced the motherboard with a issue #2 instead of issue #1 (was not convenient the repair)
  • Cleaned all keys and membrane.
  • Replaced all rusty springs of the keyboard.
  • General cleaning.
  • Moved the ROM/EPROM mod on the new motherboard.
  • Replaced the original switch with a new one, then replaced again with the old one to keep the original appearance.

from Wikipedia:

The ZX Spectrum +2 was Amstrad’s first Spectrum, coming shortly after their purchase of the Spectrum range and “Sinclair” brand in 1986. The machine featured an all-new grey case featuring a spring-loaded keyboard, dual joystick ports, and a built-in cassette recorder dubbed the “Datacorder” (like the Amstrad CPC 464), but was in most respects identical to the ZX Spectrum 128. The main menu screen lacked the Spectrum 128′s “Tape Test” option, and the ROM was altered to account for a new 1986 Amstrad copyright message. These changes resulted in minor incompatibility problems with software that accessed ROM routines at certain addresses. Production costs had been reduced and the retail price dropped to £139–£149.

The new keyboard did not include the BASIC keyword markings that were found on earlier Spectrums, except for the keywords LOAD, CODE and RUN which were useful for loading software. This was not a major issue however, as the +2 boasted a menu system, almost identical to the ZX Spectrum 128, where one could switch between 48k BASIC programming with the keywords, and 128k BASIC programming in which all words (keywords and otherwise) must be typed out in full (although the keywords are still stored internally as one character each). Despite these changes, the layout remained identical to that of the 128. The ZX Spectrum +2 power supply was a grey version of the ZX Spectrum+ and 128 power supply.

The ZX Spectrum +2A was a variant of the Spectrum +3 housed a black version of the Spectrum +2 case mouldings. The Spectrum +2A/+3 motherboard (AMSTRAD part number Z70830) was designed such that it could be assembled without the floppy disk controller or associated logic and a +2 style “datacorder” connected. Originally, Amstrad planned to introduce an additional disk interface for the +2A/+2B called the AMSTRAD SI-1, however this never appeared. If an external disk drive was added, the “+2A” on the system OS menu would change to a +3.

The power supply of the ZX Spectrum +2A used the same pinout as the +3. However, the power supply purchased with the +2A/B had “Sinclair +2″ written on the case.

source: wikipedia

Indesit T12 SI – 762 (1976) Black & White CRT of the 70′s

August 9th, 2013 1 comment
Indesit T12 (1976)

Autopsy:

The INDESIT T12 it’s a 12 inches B/W screen with 6 programs preselection and classic potentiometers tuning search for each program. It can be powered even with a 12volt source with a special socket on the rear side. (see photo)

It doesn’t weight much because it has not transformer in it but a special power supply converter. Was first 6 programs B/W television from INDESIT, earlyer model was with Rotary tuners. INDESIT was originary from Orbassano Near TORINO In Italy and indeed the telly here shown comes from there. It was a very big industry conglomerate present in all European lands even In Norvay.

INDESIT has a very heavy controversed history which is made of high loss of work places for people, financial disasters, loss of market, closing of production location and finally a complete destruction of one of the bigger Italian industry on European level. It was then brand name aquired by Merloni Elettrodomestici known as Ariston.

Video transmission made with a UHF Transmitter CH 36.

source: obsoletetellyemuseum.blogspot.it

Personal Computer IBM 5160 with Octek VGA and ADLib

August 8th, 2013 No comments
VGA ISA 8/16 BIT and ADLib ISA 8 BIT

I have upgraded my Personal Computer IBM 5160 by adding an 8-bit ISA Sound Card (adlib) and Video Card Vga 8/16 bit ISA from Octek.

Below some videos of the tests done:

Read more…

Personal Computer IBM 5160 & Monitor IBM 5151

August 7th, 2013 1 comment
Personal Computer IBM 5160 & Monitor IBM 5151

Autopsy:

from Wikipedia:

The IBM Personal Computer XT, often shortened to the IBM XT, PC XT, or simply XT, was IBM’s successor to the original IBM PC, factory equipped with a hard drive. It was released as IBM Machine Type number 5160 on March 8, 1983, and essentially the same as the original PC, with only incremental improvements. A new 16-bit bus architecture would follow in the AT. The XT was mainly intended as an enhanced machine for business use, though later floppy-only models would effectively replace the original model 5150 PC. A corresponding 3270 PC featuring 3270 terminal emulation was released later in October 1983. XT stands for X-tended Technology.

The XT originally came with 128 kB of RAM, a 360 kB double-sided 5.25 in (133 mm) full-height floppy disk drive, a 10 MB Seagate ST-412 hard drive with Xebec 1210 MFM controller, an Asynchronous Adapter (serial card with 8250 UART) and a 130 watt power supply. The motherboard had eight 8-bit ISA expansion slots, and an Intel 8088 microprocessor running at 4.77 MHz (with a socket for an 8087 math coprocessor); the operating system usually sold with it was PC DOS 2.0 and above. The eight expansion slots were an increase over the five in the IBM PC, although three were taken up by the floppy drive and hard drive adapters, and the Async card. (An IBM PC also typically had a floppy disk controller in one of its five slots; both the PC and XT also usually required a display adapter in another slot.) The basic specification was soon upgraded to have 256 kB of RAM as standard.

Slot 8 on the XT motherboard was wired slightly different than the other slots, making it incompatible with some cards and had additional signal CARD SLCTD (pin B8). This was done for cards designed to allow the XT to be connected to IBM mainframes (3270-PC). The modified slot is found only on the 5160 and 5155 Portable PC; it is not in the 5150, IBM AT, or any clone PCs. During this period, it was commonplace for ISA cards to include a jumper allowing them to work in Slot 8. Video cards initially comprised the MDA and CGA, with EGA and PGC becoming available in 1984.

source: wikipedia

Media-Tel Systems FP400 (Unknown Object)

August 5th, 2013 2 comments
Media-Tel Systems FP400

Autopsy:

I have purchased this item at a very low price (15 Euros) because he was curious.

I don’t have found any information on internet about it. The production date should be around 1989/90 in Germany. The processor used is a Motorola 68008, the same also used on Sinclair QL.

Apple ][ Europlus (Apple II Europlus) Restoration and Repair

July 31st, 2013 1 comment

This gallery shows some stages of cleaning the computer Apple ][ Europlus, Apple Disk ][.

I have also made minor repairs which i describe below:

  • Replaced the Lamp of the power-on.
  • Removing the RIFA filter capacitor (the capacitor was exploded)
  • Fixed the center hub of the Apple Disk ][.

Apple ][ Europlus (Apple II Europlus)

July 31st, 2013 No comments
Apple ][ EuroPlus with a Apple Monitor III

Autopsy:

The gallery of the Apple /// Monitor can be viewed by clicking here

from Wikipedia:

The Apple II series (trademarked with square brackets as “Apple ][") is a set of 8-bit home computers, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer (now Apple Inc.) and introduced in 1977 with the original Apple II. In terms of ease of use, features and expandability the Apple II was a major technological advancement over its predecessor, the Apple I, a limited-production bare circuit board computer for electronics hobbyists that pioneered many features that made the Apple II a commercial success. Introduced at the West Coast Computer Faire on April 16, 1977, the Apple II was among the first successful personal computers; it launched the Apple company into a successful business (and allowed several related companies to start). Throughout the years, a number of models were sold, with the most popular model remaining relatively little changed into the 1990s. It was first sold on June 10, 1977. By the end of production in 1993, somewhere between five and six million Apple II series computers (including about 1.25 million Apple IIGS models) had been produced.

The Apple II Plus, introduced in June 1979,included the Applesoft BASIC programming language in ROM. This Microsoft-authored dialect of BASIC, which was previously available as an upgrade, supported floating-point arithmetic, and became the standard BASIC dialect on the Apple II series (though it ran at a noticeably slower speed than Steve Wozniak's Integer BASIC).

Except for improved graphics and disk-booting support in the ROM, and the removal of the 2k 6502 assembler/disassembler to make room for the floating point BASIC, the II+ was otherwise identical to the original II. RAM prices fell during 1980–81 and all II+ machines came from the factory with a full 48k of memory already installed. The language card in Slot 0 added another 16k, but it had to be bank switched since the remaining CPU address space was occupied by the ROMs and I/O area. For this reason, the extra RAM in the language card was bank-switched over the machine’s built-in ROM, allowing code loaded into the additional memory to be used as if it actually were ROM. Users could thus load Integer BASIC into the language card from disk and switch between the Integer and Applesoft dialects of BASIC with DOS 3.3′s INT and FP commands just as if they had the BASIC ROM expansion card. The language card was also required to use the UCSD Pascal and FORTRAN 77 compilers, which were released by Apple at about the same time. These ran under the UCSD p-System operating system, which had its own disk format and emitted code for a “virtual machine” rather than the actual 6502 processor. The UCSD P-system had a curious approach to memory management, which became even more curious on the Apple III.

A TEMPEST-approved version of the Apple II Plus was created in 1980 by the Georgia Tech Research Institute for U.S. Army FORSCOM, and used as a component in the earliest versions of the Microfix system. Fielded in 1982, the Microfix system was the first tactical system using video disk (Laserdisk) map technology providing zoom and scroll over map imagery coupled with a point database of intelligence data such as order of battle, airfields, roadways, and bridges.

After the success of the first Apple II in the United States, Apple expanded its market to include Europe, Australia and the Far East in 1978, with the Apple II Europlus (Europe, Australia) and the Apple II J-Plus (Japan). In these models, Apple made the necessary hardware, software and firmware changes in order to comply to standards outside of the U.S. The power supply was modified to accept the local voltage, and in the European and Australian model the video output signal was changed from color NTSC to monochrome PAL – an extra video card was needed for color PAL graphics, since the simple tricks Wozniak had used to generate a pseudo-NTSC signal with minimal hardware did not carry over to the more complex PAL system. In the Japanese version of the international Apple, the keyboard layout was changed to allow for Katakana writing (full Kanji support was clearly beyond the capabilities of the machine), but in most other countries the international Apple was sold with an unmodified American keyboard; thus the German model still lacked the umlauts, for example. For the most part, the Apple II Europlus and J-Plus were identical to the Apple II Plus. Production of the Europlus ended in 1983.

source: wikipedia

CBS ColecoVision: diagnosing and fixing motherboard faults

July 26th, 2013 No comments

I have decided to repair my Coleco Vision Secam version (RGB) purchased some years ago in a full working state, today is died. Below a description of the defect and of components being replaced.

Defect: dirty sprite

  • 3 x 4116 (RAM)

MicroBee PC 85 (Model II) Keyboard Repair

July 24th, 2013 No comments

I have received this computer in excellent cosmetic condition but unfortunately with some dead keys of the keyboard.

The trick of the repair is cleaning the two little strips and the small conductive button (see the photos)

Applied Technology MicroBee PC 85 (Model II) + ROM Eprom Dump

July 24th, 2013 No comments
Applied Technology MicroBee PC 85 (Model II)

Autopsy:

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.

Download: MicroBee PC 85 ROM Eprom Dump (1496)

source: wikipedia

Timex Computer 2048 (TC 2048) – Spectrum 48k Clone

July 21st, 2013 No comments
Timex Computer 2048 (TC 2048) - Spectrum 48k Clone

Autopsy:

from Wikipedia:

The TC 2048 or Timex Computer 2048 is a computer created by “Timex of Portugal, Lda”, a branch of Timex Corporation. It was highly compatible with the Sinclair ZX Spectrum computer, although differences in the ROM prevented 100% compatibility.

Timex Portugal sold the TC 2048 in Portugal and Poland, where it was very successful. Also, a NTSC version was sold in Chile. This computer forms the basis of an improved Spectrum-compatible machine, the Spectrum SE.

Timex Sinclair was a joint venture between the British company Sinclair Research and Timex Corporation in an effort to gain an entry into the rapidly growing early-1980s home computer market in North America. The choice of partnership was natural as Timex was already the main contractor for manufacture of Sinclair’s ZX81 and ZX Spectrum computers at its Scottish plant in Dundee.

It was Timex of Portugal, though, that took on the R&D and the local manufacturing of the models to be exported to the U.S. Although both Timex of Scotland and Timex of Portugal were full subsidiaries of Timex, internal rivalry, whether unintended or purported, meant there were no contacts nor experiences shared between the two plants. Timex of Portugal also sold the Timex Sinclair models in Portugal and Poland under the Timex Computer brand.

Technical specifications:

  • CPU: Zilog Z80A @ 3.50 MHz
  • ROM: 16 KB
  • RAM: 48 KB
  • Sound: Beeper (1 channel, 10 octaves and 10+ semitones via internal speaker)
  • Display:
    • Improved ULA offering additional screen modes:
    • Text: 32×24 characters (8×8 pixels, rendered in graphics mode)
    • Graphics: 256×192 pixels, 15 colours (two simultaneous colours – “attributes” – per 8×8 pixels, causing attribute clash)
    • Extended Color: 256×192 pixels, 15 colors with colour resolution of 32×192 (two simultaneous colours – “attributes” – per 1×8 pixels)
    • Dual Screen: (two 256×192 pixels screens can be placed in memory)
    • A monochrome 512×192 mode
  • I/O:
    • Z80 bus in/out
    • Tape audio in/out for external cassette tape storage
    • RF television out
    • Composite video monitor out
    • Kempston Joystick input

Download: Timex Computer 2048 Schematic (1506)

source: wikipedia

New CBS Coleco Vision cartridges for my collection

July 21st, 2013 No comments

New CBS Coleco Vision cartridges for my collection CBS Coleco Vision cartridges

New CBS Coleco Vision cartridges for my collection.

List of cartridges:

  • Antarctic Adventure by ©1984 Konami
  • BC’s Quest for Tires by ©1983 Sierra On-Line
  • Donkey Kong Junior by ©1982 Nintendo (France Secam Version)
  • Miner 2049er by ©1982 Micro Fun/Microlab inc.
  • Omega Race by ©1981 Bally Midway
  • Pitfall by ©1983 Activision
  • Q*Bert by ©1983 Parker Brothers
  • Roc’n'Rope by ©1984 Konami
  • Schtroumpfs by ©1983 Logiciel (France Secam Version)
  • Super Action Football by ©1984 CBS Toys
  • Tarzan by ©1984 Edgar Rice Burroughs Inc.
  • Tournament Tennis by ©1984 Imagic
  • Venture by ©1983 Exidy (France Secam Version)
  • Pitstop by ©1983 Epyx
  • Looping by ©1982 Venture Line Inc. (France Secam Version)
  • Subroc by ©1982 Sega
  • Turbo by ©1981 Sega (France Secam Version)
  • Cosmic Avenger by ©1983 Universal (France Secam Version)
  • Gorf by ©1981 Bally Midway (France Secam Version)
  • Zaxxon by ©1982 Sega (France Secam Version)

Some spare parts from a Friend

July 21st, 2013 No comments

I have received from a friend a couple of components that can be used as spare parts for the repairs. Thanks Andrea.

Close-up description:

  • 1 x Commodore CBM 4040 Dual Floppy Disk Drive PCB
  • 1 x Commodore CBM 8050/8250 Dual Floppy Disk Drive PCB
  • 2 x Texas Instruments TI-99/4A PCB
  • 1 x Main powersupply of Commodore CBM 4040/8050/8250 Dual Floppy Disk Drive.
  • 1 x Sinclair ZX Spectrum+
  • 1 x Sony HB-10P MSX

Philips Videopac G7000 (PAL) RGB Video Mod

July 20th, 2013 7 comments
Philips Videopac G7000 with RGB Output

Details:

I have found this RGB mod for the Philips Videopac G7000 console fom the gamesx site and i have decided to build the circuit to see if it works.

This mod is not easy to do, especially if one has no experience in electronics, however the result at the end is spectacular.

RGB DAC Schematics (click to zoom):

Download: Philips VideoPac G7000 Schematics (1880)

source: gamesx.com

Commodore CBM 8050 Cleaning and Repair

July 14th, 2013 1 comment

This gallery shows some stages of cleaning the Commodore CBM 8050 Dual Drive Floppy Disk. Below the defects and replacement parts.

Defect:

  • Died – Status LED: RED (5 Flash) Zero page error.

Replacement parts:

  • 1 x 6502
  • 1 x 6532
  • 1 x 6522
  • The connectors of write enable sensors are inserted incorrectly.
  • Missing +5v on the PCB of the sensor circuit.
  • Dirtiness in the write enable sensor drive 0
  • Cleaning floppy drive heads.
  • Cleaning belt of the floppy drive.
  • Removing the filter capacitor.
  • The Analog PCB of the Floppy Drive is not fixed properly.
  • The Locking screws of the external box are not original.
  • Lost the felt which push the Floppy Disk vs the head.
  • Disk is present (Switch Motor) dirty.
  • General Cleaning.

Test formatting floppy disk: