KIM-1
 | |
| Developer | Chuck Peddle |
|---|---|
| Manufacturer | MOS Technology, Inc. |
| Type | single-board computer |
| Release date | 1976 |
| CPU | 6502 |
The KIM-1, short for Keyboard Input Monitor, is a small 6502-based single-board computer developed and produced by MOS Technology, Inc. and launched in 1976. It was very successful in that period, due to its low price (thanks to the inexpensive 6502 microprocessor) and easy-access expandability.
History
MOS Technology's first processor, the
Many books were available demonstrating small assembly language programs for the KIM, including The First Book of KIM by Jim Butterfield et al.[1] One demo program converted the KIM into a music box by toggling a software-controllable output bit connected to a small loudspeaker. Canadian programmer Peter R. Jennings produced what was probably the first game for microcomputers to be sold commercially, Microchess, originally for the KIM-1.
As the system became more popular one of the common additions was the Tiny BASIC programming language. This required an easy memory expansion; "all of the decoding for the first 4 K is provided right on the KIM board. All you need to provide is 4 K more of RAM chips and some buffers."[2] The hard part was loading the BASIC from cassette tape—a 15-minute, error-prone ordeal.
Finally, there was the Synertek SYM-1 variant, which could be said to be a machine halfway between the KIM and the AIM; it had the KIM's small display, and a simple membrane keyboard of 29 keys (hex digits and control keys only), but provided AIM-standard expansion interfaces and true RS-232 (voltage level as well as current loop mode supported).
Description
The KIM-1 consisted of a single
Also included were six 7-segment LEDs (similar to those on a pocket calculator) and a 24-key calculator-type keypad. Many of the pins of the I/O portions of the 6530s were connected to two connectors on the edge of the board, where they could be used as a
One of these connectors also doubled as the power supply connector, and included analog lines that could be attached to a cassette tape recorder.
Earlier
The KIM-1 included a somewhat more complex built-in Terminal Interface Monitor software called TIM that was "contained in 2048 bytes of ROM in two 6530 ROM/RAM/IO arrays".[5] This monitor software included the ability to run a cassette tape for storage, drive the LED display, and run the keypad. As soon as the power was turned on, the monitor would run and the user could immediately start interacting with the machine via the keypad. The KIM-1 was one of the first single-board computers, needing only an external power supply to enable its use as a stand-alone experimental computer. This fact, plus the relatively low cost of getting started, made it quite popular with hobbyists through the late 1970s.
Video display
The designer of the TV Typewriter, Don Lancaster, developed a low cost video display for the KIM-1. The add-on board would display up to 4000 characters on a TV or monitor. A typical configuration would be 16 lines of 32 upper case only characters. The board had only 10 low cost ICs and used the KIM's memory for the screen storage.
The TVT-6 project appeared on the cover on Popular Electronics in July 1977.[6] The complete kit could be ordered from PAiA Electronics for $US34.95.
Lancaster expanded this design to do color and simple graphics in The Cheap Video Cookbook.[7]
Specifications
- CPU: MCS6502, clocked at 1 MHz
- 2× PIO programmable interval timer
- 8× 6102 static RAM1024 × 1 (1024 bytes)
- 6× 7-segment LEDs
- 24-key calculator type keypad
- 2× serialports
- Terminal Interface Monitor (TIM), that handled booting, keypad, seven-segment LEDs, and cassette tape
Tape format
Each bit is represented by three 2.484 ms long tones. The first is always 3700 Hz, the middle is 3700 Hz for "0" or 2400 Hz for "1", and the last one is always 2400 Hz. This gives an effective bit rate of 134.2 bit/s. Detection is done through a PLL using LM565.[8]
The format of data on the tape is: 100 bytes with the value 0x16 (SYN, Synchronous Idle), one byte with the value 0x2A (*), the record identification number, the start address (two characters for the low byte of address, two characters for the high byte), the end address (in the same format), the actual data, one byte with the value 0x2F ("/" character ), a two-byte checksum, and two bytes with the value 0x04 (EOT, End Of Transmission).[8]
Each byte of memory is stored as two sequential ASCII characters on tape, for example, hexadecimal B5 in memory (181 decimal) would be stored as two sequential ASCII characters "B" and "5" (42 and 35 hexadecimal).[8]
See also
References
- ISBN 0-8104-5119-0.
- ^ Simpson, Richard (May 1976). "A Date with KIM". BYTE. Vol. 1, no. 9. Byte Publications Inc. p. 14.
- ^ MCS6500 Microcomputer Family Hardware Manual. MOS Technology Inc. January 1976. p. 71.
- ^ "MOS KIM-1". BYTE (advertisement). Vol. 1, no. 8. Byte Publications Inc. April 1976. p. 15.
- ^ "What's New, KIM-o-sabee?". BYTE. Vol. 1, no. 8. Byte Publications Inc. April 1976. p. 14.
- ^ Lancaster, Don (July 1977). "Build the TVT-6: A Low-Cost Direct Video Display". Popular Electronics. Vol. 12, no. 1. Ziff-Davis Publishing. pp. 47–52.
- ISBN 0-672-21524-1.
- ^ a b c "Users Manual V1.0". 091208 users.telenet.be
External links
- KIM-1 and collection of old digital and analog computers at oldcomputermuseum.com
- KIM-1 6502 website at the Wayback Machine (archived August 31, 2022) – erik.vdbroeck's resource site for the KIM-1, with several HTML'ized manuals and books
- Instructions on building your own KIM-1
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