1977 Radio Shack TRS-80 Model I
The Tandy TRS 80 model 1 was the first member of one of the most famous computer family. It was one of the first home computer and was launched at the same time as famous computers like the Apple II or the Commodore PET. Beside, Tandy competitors nicknamed was “Trash-80”.
The TRS-80 was developed was developed within the Radio Shack engeneering group, based upon several processor chips, SC/MP, PACE, 8008, 8080 and finally the Z80.
It used a black & white TV set, made by RCA, without tuner as monitor. The earlier models use a poor basic called Basic Level 1 (the Basic and the OS fit in the 4 KB ROM!). It was replaced later with the Basic Level 2 which needed a 12 KB ROM.
To offset its poor characteristics, Tandy developed a device called Expansion Interface which brings a lot of new features : additional 16 or 32kb RAM, two tape unit connectors, a printer port, a floppy disk controller, a serial port and a real time clock.
Tandy did as well 5, 10 and 15 MB hard drives. The case for them is about the size of a small PC tower. It’s possible to fit 2 drives into each case. They were compatible with all TRS-80 versions.
When it was connected to a floppy disk unit, the TRS-80 uses the TRS DOS operating system, it was pretty bugged and most of the TRS-80 users prefered NEW DOS, it was an operating system done by a third-party company called Apparat. This OS was the real TRS-80 operating system.
LS-DOS was also an excellent DOS, superior to NEW DOS for most users. Interestingly, Microsoft’s MS-DOS became more and more like LS-DOS each time it was updated, although never as good. LS-DOS was finally adopted by Tandy as the official DOS for the Model 4.
Documentation for all the TRS machines was superb. Even Microsoft provided documentation for its BASIC interpreter listing all the machine calls. You could use these calls when programming with either machine code or BASIC.
| NAME | PET 2001 |
| MANUFACTURER | Commodore |
| TYPE | Professional Computer |
| ORIGIN | U.S.A. |
| YEAR | 1977 |
| BUILT IN LANGUAGE | Commodore Basic 1.0 |
| KEYBOARD | 73 key ‘chicklet’ keyboard with numeric keypad |
| CPU | 6502 |
| SPEED | 1 mHz |
| RAM | 4 KB (early version) then 8 KB |
| VRAM | 1 KB |
| ROM | 14 KB |
| TEXT MODES | 40 x 25 |
| NAME | TRS 80 MODEL I |
| MANUFACTURER | Tandy Radio Shack |
| TYPE | Home Computer |
| ORIGIN | U.S.A. |
| YEAR | 1977 |
| BUILT IN LANGUAGE | Basic Level 1 (4k ROM models) Basic Level II (12k ROM models) |
| KEYBOARD | Full-stroke keyboard, 53 Keys, optional numeric keypad |
| CPU | Zilog Z80 |
| SPEED | 1.77 MHz |
| RAM | 4 kb / 16 kb depending on models (up to 48 kb) |
| VRAM | 1 kb |
| ROM | 4 kb (Basic Level 1) or 12kb (Basic Level 2) |
| TEXT MODES | 32 x 16, 64 x 16 |
| GRAPHIC MODES | 128 x 48 |
| COLORS | monochrome |
| SOUND | None |
| I/O PORTS | Monitor, cassette interface, expansion port |
| OS | TRS DOS – NEW DOS |
| PRICE | #26-1003 : Model I, Level I, 16K = 700 € (France,81) #26-1004 : Model I, Level II, 4K = 640 € (France,81) #26-1006 : Model I, Level II, 16K = $1099 |
| GRAPHIC MODES | None |
| COLORS | Monochrome |
| I/O PORTS | IEEE 488, Parallel port, second, ”user port” for 8-bit I/O, cassette port inside the case, rarely used |
| BUILT IN MEDIA | tape recorder |
| POWER SUPPLY | Built-in power supply unit |
| PRICE | £700 (8 KB RAM – 1978) |
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Filed under: 70s Computers - @ January 31, 2022 11:23 AM