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Fixing a Radio Shack TRS-80 Model 1

October 12th, 2012 3 comments

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):

Before repair After repair Replaced components

 

Keyboard repair (replacement of internal contacts):

Repair Keyboard Repair Keyboard Repair Keyboard

 

Micro Computer Technical Reference Handbook:

Download: TRS-80 Micro Computer Technical Reference Handbook (2588)

Radio Shack TRS-80 Model 1 + Video Display

October 12th, 2012 No comments
Radio Shack TRS-80 Model 1 + Video Display

Autopsy:

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

Turbo Chameleon 64 beta firmware 8b released

October 11th, 2012 No comments

Turbo Chameleon 64 is an extremely user-friendly cartridge that can be used without opening the computer. It is just plugged to the expansion port of the C64.

The Turbo Chameleon 64 cartridge can also be operated as a stand-alone unit (since it’s basically an FPGA computer like the C-One or the Minimig in a C64 cartridge case), replacing the computer, the floppy drive and the heavy power supply.

When used as a stand-alone unit, a USB power adapter or active USB hub can be used as a power source.

Changelog:

  • New VGA controller with new modes and VIC-II sync.
  • Tripple buffering mode added for properly displaying IFLI pictures.
  • Scale-2x video scaling algorithm added.
  • Scanline emulation added.
  • In cartridge mode real CIAs registers and interrupts are used (allows use of a modem).
  • In cartridge mode real VIC-II registers and interrupts are used (allows use of a lightpen).
  • Fixed I/O assignments for FPGA (lower power use).
  • Lowlevel SD-card functions now use multiple block reads if possible, which increases linear reading speed by about 40 to 50% (most noticeable on large files, such as REU images)
  • BUGFIX: fixed error handling and timeouts of the IEC routines, which makes all related operations more robust.
  • BUGFIX: added missing timeouts to SD-card functions.
  • Joystick port 1 now also works for navigating the menus.
  • BUGFIX: on some C64s pressing shift would result in phantom keypresses (F1/F2) under some conditions.
  • NEW: various new VGA modes and other options for the new VGA controller (see manual)
  • Improved loading speed of file inside T64 images.
  • Improved keyboard handling to make the browser a bit snappier.
  • BUGFIX: the size of the character ROM saved by the ROM saver was incorrect.
  • BUGFIX: .wav player stops at the end of the file and does not continue playing garbage.
  • BUGFIX: files bigger than 2k are displayed correctly by the .txt viewer.
  • BUGFIX: when copying files out of a t64 image the resulting file was missing the last two bytes and/or the last block was missing completely.
  • BUGFIX: filecopy from/to a IEC device did incorrectly abort after 1 block.
  • BUGFIX: filecopy filename character set conversion was broken.
  • BUGFIX: AR/RR ROM was not correctly disabled when autostarting programs from the filebrowser with AR/RR enabled as default cartridge.
  • NEW: added DOS wedge command (see manual)
  • NEW: added load and save commands (see manual)

Download: Chameleon 64 beta firmware 8b (1765)

source: beta.icomp.de

Categories: Firmware, News & Rumors, Today

C64 Game: Get ‘Em DX +5HD [pal/ntsc] / Dungeon Blaster +8H

October 11th, 2012 No comments

Some new games (Cracked / Trained or Unrealeased) for Commodore 64 have been released from your favorites groups: Genesis Project and Laxity.

Download:

source: csdb.dk

SNDH Atari ST YM2149 Archive v3.4 released.

October 9th, 2012 No comments

SNDH archive v3.4 released. 73 SNDH-files added or updated!

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 v3.4 (1780)

source: sndh.atari.org

Categories: Atari, News & Rumors, Today

C64 Game: Trashman (Creative) +2DH / Yucatan +5HFD 101% …

October 6th, 2012 No comments

Some new games (Cracked / Trained or Unrealeased) for Commodore 64 have been released from your favorites groups: Mayday!Antarctica and Laxity.

Download:

source: csdb.dk

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September 30th, 2012 1 comment

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September 29th, 2012 1 comment

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Categories: Firmware, News & Rumors, Today

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