This machine was near-and-dear to me as it was my first real computer, an Ohio Scientific Superboard II. In 1979 I got my machine, a 6502-based single-board computer with a whopping 8K of RAM and BASIC in ROM. The board was completely self-contained, requiring only a 5V, 3A power supply to run (I built my own using a 78H05 regulator). Ohio Scienti
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fic (OSI) started business in 1975 and through the late 1970`s and early 1980`s produced a series of 6502-based machines called the "Challenger" series. Like contemporaries (including the Apple and the Commodore machines), OSI systems used the low-cost 6502 processor. Created as a low-cost response to Motorola`s 6800 processor, and commercially available (in production quantities) in 1976, the 6502 could use all readily-available and inexpensive 6800 peripheral chips (as OSI did to save cost). The 6502 achieved low costs through a number of design features including the fabrication in NMOS technology and use of "zero-page" memory which allowed reduction of the number of on-chip registers to six. The 6502, in a design reminiscent of the PDP-8 processor, allows fast access to the first 256 bytes of RAM from most instructions (making the 6502 almost RISC-like). The next 256 bytes (0x100 through 0x1FF) are prewired as the stack. All 6502 systems, therefore, require at least 512 bytes of RAM located in the lowest memory page and unlike the contemporary Z-80 processor, programs cannot simply be located at address zero (the 6502 actually fetches a vector for the start program from the highest two bytes - a ROM must be located there). The earliest catalog I could locate was the spring 1978 issue. That year, OSI offered several models based on a single-board CPU, the model 500 card. This card featured 8K BASIC-in-ROM, 4K of RAM on...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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