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Testing the BASIC Computer on Olivetti monitor and Altec keyboard
08/07/2022 at 20:58 • 0 commentsI also tested the completed computer on an Olivetti monitor (that I own), and also a different PS/2 keyboard. Results were equally satisfying.
I have to say I enjoy using the "Terminal-BASIC" programming language (by Andrey Skvortsov) which is the initial reason I put together the whole project of the "BASIC Computer"; it's user-friendly and quite versatile in its features.
The Terminal-BASIC startup message greets you when you boot up the machine:The total hardware of this computer is really minimal: just 3 boards. The only board that needs to be assembled is the "Computer Terminal Board" (lower one of the three). The other two are out-of-the-shelf parts: microSD-Card module and Arduino MEGA2560 .
More details on programming the chips for the "Computer Terminal Board" and assembling the board later. For now, just take a look at the pictures and feel some magic of the 80's ! :-)
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Assembling the PCB of the "Computer Terminal Board" and testing
08/07/2022 at 20:39 • 3 commentsI started assembly of the board as soon as I had some free time: the next day after delivery. The necessary electronic parts are common and, anyhow, I already had those from the breadboard prototype, which was dismantled to bits.
The finished assembled "Computer Terminal Board" (with wire connections for the subsequent testing) can be seen below:
Some testing was done (on the kitchen table!), as soon as I put together the whole system; that involved connecting the Arduino MEGA2560 (in the middle) to the microSD card board (on the right) and to the Computer Terminal Board I had just assembled (on the left). The colored plugs, in the upper part of the photo are, from left to right: 1. PS/2 Keyboard (purple) 2. Video Out (yellow) 3. Power input 7.5V (black)...
... and there you have it:
The complete, working, "80's style BASIC Computer with Terminal-BASIC" !The computer monitor pictured here is a HANTAREX.
The assembled "Computer Terminal Board" worked nicely as you can see in the photo; the picture on the monitor screen looks crisp and solid. -
PCB's arrived !
08/07/2022 at 20:08 • 0 commentsPCB's finally arrived a couple days ago! I ordered them at:
This is the first time I ordered PCB's from them. And it was a wise choice.
The merchantise was carefully wrapped in foam plastic foil and the PCB's were nicely stacked and vacuum packed.And this what I expected to see, according to my design (this is a preview from the CAD app):
The real thing looks exactly as it should have, according to the Gerber files I uploaded on their web site. So, very accurate fabrication of my design.
I must also mention that the whole process of ordering from PCBWay and tracking the package was simple and swift. Boards arrived within a few days.
I definitely recommend PCBWay for quality manufacturing of your own pcb's. -
A Printed Circuit Board (PCB) for the project
07/14/2022 at 17:22 • 2 commentsSo, I decided to design a PCB for my project. This PCB hosts the "Dummy Terminal" circuits and is referred as "Computer Terminal Board" on the PCB. I used Grant Searle's schematic of the "Video & Serial/Keyboard Interface" (named "Video&Keyboard,SerialBoard" in the project Details section), with just minor modifications: 1. I added two ICSP ports for programming the microcontrollers without physically removing them from the circuit. 2. Decoupling capacitors were added to all 3 ICs.
This particular design of the PCB is double-sided with vias.
As soon as I receive the actual boards I'll post some update. Hopefully, this PCB will give the "80's Style BASIC Computer with Terminal-BASIC" a more robust "body" after the successful testing of the project on breadboard.
P.S. About the ICSP headers: The need to add ICSP (InCircuitSerialProgramming) headers on this board was realized when I tried to modify the software in the ATmega328P's (specifically, the "Video" ATmega328P) in the breadboard prototype. Each and every time, I had to remove the chip from the breadboard and insert it into a separate programmer (STK500); this proved to be cumbersome. The other alternative is to leave the chip on the PCB and use ICSP programming; for that, you use only 6 pins of the IC, which are broken out to the ICSP header. Just connect a serial programmer to the ICSP header (I used the STK500) and program the chip in place.