Overview
This is one of my first pcb I decide to assemble. Schematic of this computer was published first time in russian magazine “Young technic” in 1988. (Are you subscribe to this magazine? I am - yes. But in 1988 I was 10 year old, so to my first experience with computers was only 5 years later).
So that is wonderfull rare computer with history.
Computer contains 3 pcb - cpu module, video controller and keyboard. Assemble fast and easy. Debugging mostly not required in case of working chips. I test chips before and solder it to boards (except CPU, RAM and ROM)
On first run without RAM show on segments FFFF 11, without ROM 3900 39 or 0039 00.
CPU keys description:
0 addr - Write data to ram from ‘addr’
1 - - Write data to ram from 0xc000
2 - - Read data from ram from 0xc000
3 - - Test display (steps from 0 to F on both segments)
4 - - Test ram (fill with 0, after 1 and check both writes). After successfull print c400
5 addr - Read data from RAM from ‘addr’
6 - - Run programm from 0xc000
7 addr - Run programm from ‘addr’
8 a1,a2- Calculate CRC a1 - a2
9 a1,a2- Write data a1 - a2 to tape
A addr - Read data from tape with offset ‘addr’
B - - Display time
C c3fd - Set time: seconds, minutes, hours (3 bytes)
Links
Book (mostly original) about programming basis electrotechnics, also include schemas and details about building ut88
Manual build computer (in russian)
Firmware for rom
Gerber cpu module
Schematic in KiCAD from me
BOM list
Labels for keys
TODO
Of course run CP/M and build disk
Photo
