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Basic Operation Complete

A project log for MicroVIP

This is a project to celebrate the 40th anniversary of the RCA COSMAC VIP microcomputer!

David HunterDavid Hunter 08/29/2017 at 03:140 Comments

The basic MicroVIP is working!   Here is the status so far:

First, I built up the basic hardware with the VIP feature set (except for the tape interface).   There are some features that can be added later.   I got the processor, RAM, ROM going using a modified version of the UT4 monitor.   I got things working in ModelSim first.  Next, I used a USB to TTL serial adapter (3.3V Prolific) to interact with the computer.   

With UT4 and the serial port, I was able to do some basic tests.   I wrote simple programs to test the hexadecimal keypad.   I also could test the speaker.

From there, I added the VIP ROM and video.   With some debugging using ModelSim, I got it working in hardware.

So far, it operates as a standard VIP but with only memory read and write working.   The speaker does beep with the Q line.   The keypad is functional as well as the video output.

Plans:

Next, I want to get the SPI working to use the serial flash as a tape emulator.   I'm using a 16MB serial flash because it's very inexpensive ($5) and easy to acquire.   I realize for a 1977 type computer that is a near infinite amount of space.  I will also modify the VIP ROM software to use the serial flash.

After that, I want to have CHIP-8 in RAM on power up and recreate some of the projects in the VIP manual.

For the future, I'd like to add a Tiny BASIC and an ASCII keyboard interface

Tools needed:

Quartus II 11sp1 (This is the last one to support the Cyclone II)

Altera ModelSim (comes with Quartus)

USB Blaster (or equivalent)   I have a Terasic Blaster

Composite Video monitor

+5V Wall Wart (~1W) to power the Cyclone board

USB to TTL cable (3.3V I/O)  I'm using the one from Adafruit

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