I received as a gift… we start badly,i have recover, we are not there, i purchased, much better, yet another computer from Radio Shack that was missing in my collection.

The computer equipped with several manuals and Floppy Disk was given to me by a dude (thanks Scott) from the United States, he had written “near mint” and is this phrase that attracted me.

The Computer is a Radio Shack TRS-80 Model 4 (GATE ARRAY) therefore of last production with cathode ray tube with green phosphors.

The seller was not joking saying that it was “near mint” and working, the computer is kept very well it almost seems like it has never been used, it can be observed from the cathode tube, from the pcb of the monitor and from the flyback transformer, keyboard, External and internal Case and from the power supply, the usual ASTEC, which has never warmed up, perfect.

The warranty sticker was also intact.

Since there was nothing to clean/repair i have made some hardware enhancements and little replacements.

What i have done:

• Replacement of the 3 filter capacitors (RIFA) which i usually remove and i don’t replace.
• Converted the ASTEC power supply from 115V to 230v because this version of the power supply allows it because has a 115v/230v switching.
• Replaces the 115v power plug with a schuko.
• Various labels to identify the computer has been converted to 220v.
• Installed 64k RAM to update the Model 4 to 128k (blue wire mod as well)
• Dual ROM to BOOT from FreHD or from Floppy Drive. I have used the Jim Brain ROM-el 2364 which uses a Flash ROM (AT49F001AN) but with a standard Mask ROM 2364 pinout.
• Installed a switch for Dual ROM hidden in the ventilation slots without drilling the case.

All test are made with the FreHD interface by Ian Mavric.

Gallery:

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Download: TRS-80 M4 GA Dual Boot ROM (610)

I thank my dear friend Ciro (www.ti99iuc.it) for giving me the Personal Computer Radio Shack Tandy 4000SX.

Some photo:

Tandy 4000SX uses a intel 80386SX microprocessor at 16 megahertz, 32-bit CPU Offers true Intel 386 processing in a 286 hardware environment.

Tandy designed and engineered with full IBM PC/AT compatibility. Uses hardware and software compatible with the IBM standard for IBM PC/XT/AT computers.

source: radioshack.com

The Tandy Radio Shack TRS-80 DT-1 is a video terminal. It is ideally suited for communications with the TRS-80 Model 16 Multi-User Office System or with other host computers. With a low-cost Tandy acoustic coupler it can also access time-sharing information networks.

Gallery:

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State-of-the-Art Design:

Unlike many terminals, you can easily set up and change the configuration on your DT-1 from the keyboard. A revolutionary non-volatile memory that retains your terminal configuration even with power off and without battery backup!

Multiple Emulation Modes:

The DT-1 is completely code compatible with four standard terminal protocols.

• Televideo 910
• Lear Siegler ADM-5
• ADDS 25
• Hazeltine 1410

The 30.5 cm diagonal CRT displays 24 lines of 80 upper and lower case characters per line. Special single-character symbols are used to display control characters.

Dual-Speed Repeat:

Any character can be repeated by merely holding down the desired key. After several characters are repeated, the DT-1 will automatically repeat the characters at a faster rate.

Two Printer Ports:

The TRS-80 DT-1 can be equipped for hardcopy output by connecting a printer to the built-in RS-232C serial interface or parallel interface.

Special Features:

A local monitor mode lets you enable printer ports and position the cursor using local control and escape modes. The carrige return key can be programmed with or without a line feed. Control key termination codes are also user programmable. An electronic bell is standard.

TRS-80 DT-1 Highlights:

• Data Transfer: 75,110,150,300,600,1200,2400,4800,9600,19200
• Cursor: Four keyboard-selectable types: Steady, Blinking Block, Steady or Blinking Underline.
• Video Attributes: Normal, reverse, Invisible, Blink, Underline and Half-Intensity Video.

Download:

• Tandy DT-1 Owners Manual (2533)
• Tandy DT-1 Service Manual (1546)
• Tandy DT-1 Advertisement (1344)
• RSC-9 Computer Catalog (1483)
• Tandy DT-1 Video Monitor Service Manual (1481)

Video:

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 (1426)
• TRS-80 Model III LDos v5.31 in IMD Format (1388)

Video of some games with sounds:

source: wikipedia

Autopsy:

from Ira Goldklang’s TRS-80.com Homepage:

This is the fast way to transfer data from one location to another – by telephone with the Telephone Interface II. It’s a full “originate/answer” acoustic coupler which allows two TRS-80‘s to talk to each other. You can also communicate with another computer which has “originate only” capability (like our Telephone Interface I). You can pass all types of data or prograas between computers, or one of you can operate the other’s computer via the telephone lines. No direct connection to the telephone line is required.

It’s very simple to operate. Just dial the phone number at the location of the TRS-80 you desire to communicate with; after the connection is made, each telephone handset is placed on its interface. Now you’re ready to receive and transmit data. Requires RS-232 Serial Interface Card, Expansion Interface, RS-232 Conununications Package and Level II. Adds versatility to your TRS-80.

Specifications: Baud Rate: Up to 300. Mode: Originate and Answer, full or half duplex. Receive Sensitivity: -45 dBm. Power Requirement: U.L. listed 120-volt AC power module. Size: 2-3/8 x 4-3/4 x 10-1/4″.

source: trs-80.com

Autopsy:

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Thanks to Paolo Cognetti for giving me this device in good conditions.

Plug ‘n Power Programmable Appliance/Light Controller it’s an old device for the TRS-80 Color Computer for home automation.

Object consists of Plug ‘n Power, Appliance and Light Controller, two cords, a manual, and battery test card.

Download: Plug & Power Appliance and Light Controller (PDF) (2599)

Keep your system in top condition when it’s not in use. Custom vinyl covers fit snugly over the Radio Shack TRS-80 Model 1.

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I have gathered all photos of some phases of the work that i have done on the TRS-80 Model 1.

Below the descriptions:

• Cleaning of Nicotine.
• Replaced a bad capacitor.
• Testing.
• Floppy Drive before restoration.
• Replaced Australian Power Connector of the Floppy Drive.
• Restoration phases of the Floppy Drive.
• *Making the floppy disk for TRS-80 Model 1.
• Audio patch cable to hear the sound of the games.

*Is not been easy to make the Floppy for the TRS-80 Model 1 SSSD 35 TRK in FM format. Fortunately i have a old motherboard Pentium 133 with the right IO chip that supports writing format: MFM / FM SSSD.

Download: Some TRS-80 Model 1 games in ImageDisk format. (1112)

Video:

• Radio Shack TRS-80 Model 1 (Testing Floppy Drive)
• Radio Shack TRS-80 Model 1 (Frogger with Sound)
• Radio Shack TRS-80 Model 1 (Attack Force with Sound)

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

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 (2396)

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

Autopsy:

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Some accessories for the Home Computer TRS-80 Color from Radio Shack.

In this rainy day i have decided to commit myself to create a boot floppy disk for my Tandy Radio Shack TRS-80 Model 4P.

The right steps to create the boot disk:

Download LS-DOS or TRSDos (DMK version) floppy image from here , now you need to use the DMK2IMD program, a tool inside the package ImageDisk to convert the DMK floppy image to IMD (ImageDisk), then … burn it with ImageDisk.

Download:

• LS-Dos v6.3.1 (IMD) (1620)
• TRSDos v6.2 (IMD) (1692)

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. 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 3000 of its Radio Shack (Tandy in Europe) storefronts.

The Model 4 shipped with TRSDOS 6, an enhanced version of LDOS by Logical Systems and a vastly superior operating system to Tandy’s earlier TRSDOS offerings. When the Model 4 booted into TRSDOS 6 the video display switched into 80×24 mode and the entire 64KB address space was mapped as RAM. The Model 4 was also capable of running all Model 3 software when a Model 3 operating system disk was detected and loaded during bootup with a 64×16 video mode and Model 3 ROMs mapped from address zero.
TRS-80 Model 4P.

The Model 4 also had the ability to display 640×240 or 512×192 high-resolution monochrome graphics with an optional board. A “luggable” version known as the Model 4P (1983) was a self-contained unit with a case design similar to that of a portable sewing machine.

Early versions of the Model 4 mainboard were designed to accept a Zilog Z8000 16 bit CPU upgrade board to replace the Z80 8 bit CPU but this option was never released.

source: wikipedia