Picture of TRS-80 Model I

The TRS-80 Model I, or just TRS-80 Microcomputer System as shown on the computer itself, was introduced in August 1977. It was one of the first low cost microcomputers available to the general public in large numbers, listing for $600 for a 4k machine. Given the fact that it was distributed through Radio Shack stores, it's distribution network was already in place and quite large. The machine initially came with 4k of RAM amd included Level I BASIC and later was upgraded to 16k of RAM with the addition of a numeric keypad to the keyboard and Level II BASIC. Unfortunately, it's image soon started to be tarnished by problems caused by things such as quirky connections between the computer and it's external expansion chasis, quickly earning it the nickname 'Trash-80'. In spite of these problems, the machine gained quite a following and was to be the first in a long line of computers sold through Radio Shack stores. It was followed by the TRS-80 Model III which was essentially the Model I and it's display placed together in a single desktop enclosure. The Expansion Interface, Tandy catalog# 26-1140, -41, & -42, allowed the addition of upto 32k of RAM, up to 4 disk drives, serial and parallel devices. According to Tandy's website, more than 200,000 TRS-80 computers were sold from 1977 to 1981

The following are the various Tandy catalog numbers for the various Model I configurations:

• 26-1001 Model 1 Level 1 4k CPU/Keyboard
• 26-1003 Model 1 Level 1 16k W/Keypad CPU/KB
• 26-1004 Model 1 Level 2 4k CPU/KB
• 26-1006 Model 1 Level 2 16k W/Keypad CPU/KB
• 26-1006-1 Model 1 Level 2 16k WO/Keypad CPU/KB
• 26-1051 Model 1 Level 1 4k System (26-1001, 26-1201, 26-1205)
• 26-1053 Model 1 Level 1 16k W/Keypad System (26-1003, 26-1201, 26-1205)
• 26-1054 Model 1 Level 2 4k System (26-1004, 26-1201, 26-1205)
• 26-1056 Model 1 Level 2 16k W/Keypad System (26-1006, 26-1201, 26-1205)

Some of the options sold by Tandy for the Model 1 include:

• 26-1101 16k Memory & Keypad upgrade
• 26-1102 16k Ram Kit
• 26-1103 Numeric Keypad
• 26-1104 Model 1 Lowercase Kit
• 26-1120 Model 1 Level 2 ROMS
• 26-1132 Model 1 5 meg adapter kit
• 26-1140 Expansion Interface 0k
• 26-1141 Expansion Interface 16k
• 26-1142 Expansion Interface 32k
• 26-1143 Model 1 Double Density Disk Kit
• 26-1145 Model 1 RS232-C Board
• 26-1160 Model 1 Disk drive #0
• 26-1161 Model 1 Disk drive #2,3,4
• 26-1201 Model 1 Video Display
• 26-1205 Cassette Recorder (also cat# 41-841)

I have two Level II machines, one with the keypad and one without, both with 16k, as well as the Expansion Interface with 32k and various options. As was common at the time due to fualty connections caused by the solder-coated edge connectors then used by Tandy, my Level II machine which lacks the keypad has had a set of gold plated edge connectors fitted, matching those which were also applied to the Expansion Interface. The Tandy catalog numbers were taken from Tim Mann's lengthy list of Tandy catalog numbers.