TRS80 Model 1 computer

trs80 model1 level2 This page is about my very first real computer that I bought with the money from my first savings account, the famous TRS80 Model 1 level 2 computer. In 1980 there was little choice in hobby computers, there was the Sinclair ZX-80, the Commodore Vic-20 and the TRS-80 and after much consideration I decided that the TRS-80 wss the best. The TRS-80 had just been on the market for three years and I bought one of the first Level II versions. I had been making digital circuits since I was fourteen, read everything whatever was available about computers and digital technology and learned to program on a simple Basic computer board in Basic and Assembler. In no time I had expanded the memory and increased the speed and I did my first repairs to the TRS80 computer. I became a member of the users' association and experienced that in the Netherlands we had 1024 members. I then also started working for Tandy and sold many TRS80 computer systems and wrote a lot of software in my spare time and even sold software for the TRS80. At a certain point I knew the TRS80 Model 1 Level II computer inside out. I also loved Adventure games and became friends (to this day) with Scott Adams who was the most well-known developer of Adventure games. The TRS80 Model I level II computer has been my good companion for many years of my life and in a way it even determined my career. After the TRS-80 I bought the Sinclair Spectrum and the MSX (also because they all have a Z80 processor). I went to work for Micro Technology (and indirectly for Philips MSX) and developed MSX hardware and software. I have always cherished the TRS-80 as my very first real computer, but unfortunately it was lost during a move. I have since bought an old copy again, this first computer will always be special to me. On this page I collect everything useful information about the TRS-80 model I level II computer.

Specifications if the TRS80 Model 1 computer

  • Name: TRS 80 Model I
  • Company: Tandy Radio Shack
  • Kind: Home Computer
  • Made in: U.S.A.
  • Year: 1977
  • Basic: Level 1 (4k ROM models)
  • Basic: Level II (12k ROM models)
  • Keyboard: 53 keys
  • CPU: Zilog Z80 / 1.77 MHz
  • RAM: 4 kb / 16 kb
  • VRAM: 1 kb
  • ROM: 4 kb (Basic Level 1) or 12kb (Basic Level 2)
  • Textmode: 32 x 16 of 64 x 16
  • Graphics: 128 x 48 pixels
  • Color: Black and white (green with screen in front of monitor)
  • Sound: None
  • I/O: Monitor, cassette interface, expansion port

Links to information, documentation and tips

A very extensive description with schematics of the TRS80 Model I level II computer.
Sams ComputerFacts - Model I (1985)(Howard Sams)(pdf)

The well-known technical reference manual that Tandy sold and which was very poorly available.
Radio Shack TRS-80 Micro Computer Technical Reference Handbook 2nd

This is the technical reference manual of the TRS80 expansion interface.
Expansion Interface Service Manual (19xx)(Radio Shack)(pdf)

Wikipedia's page about the TRS80 model 1.
TRS80 wikipedia page

A very complete page with information about the TRS80 model 1.

Another very complete page with information about the TRS80 model 1

A nice page about bringing a TRS80 Model 1 computer back to life.

A site with a lot of information about all TRS80 computers (Ira Goldklang).
Ira Goldklang's TRS-80 Revived Site (Engels)

Last update: 11-05-2022

Disclaimer: All pages on this Web site are copyrighted by Hein Pragt, unless otherwise noted. I strive for accuracy but cannot be held responsible for any errors in the content. For questions about the content of this site or persmission to copy you can contact me at: (email: is registered under KvK number: 73839426.