Micro UK101

Posted by musovern on May 10th, 2018 in Micro UK101, Single Board Computers | 0 comments

The micro UK101 described here is by Grant Searle effectively the stripped-down “core” of the original UK101, and is no way intended to be the full UK101 implementation. The display and the keyboard circuitry and, instead, used a terminal emulation program (eg HyperTerm for Windows) as the keyboard/display. This has resulted in a very simple circuit which is suitable for use embedded-control applications as well as a fully-functioning computer. I have tried to make as few functional changes as possible to allow old software to work, wherever possible. As a result the BASIC ROM is totally untouched.

Although not the very simplest that can be designed, it is still straightforward. It is slightly more complicated due to the following:
1. The CPU is to run at 1MHz to match the original UK101. As a result, suitable clock division was needed to allow suitable serial speeds to be produced.
2. The ROM enabling in the original UK101 is not contiguous (in one block). This circuit is designed to use the original software on the UK101 (patched as needed) so the ROM needed to be enabled at two separate places in the memory map. The ACIA and RAM also needed suitable address decoding.

Some patches have been applied to the CEGMON ROM to ensure ALL I/O is via the serial port only, not to the screen.

 

The MicroUK101
3K RAM, expandable on-board to 8K 32K RAM
300 baud serial/cassette interface 19200 baud serial interface. No cassette port needed as the PC can store the prorgams.
16×32 display All display via the terminal on the PC
TV output and serial I/O Only serial I/O
1MHz 6502 CPU 1MHz (although up to 8MHz CPU clock speed is possible)
Keyboard input (32 keys soldered directly onto the board) Input via serial connection
12 inch x 15 inch board 3 inch x 3 inch board
1.5A supply current 200mA supply current, probably less if CMOS CPU used.
Open-board construction (uncased) Up to you!
Microsoft BASIC Microsoft BASIC
Various monitors were available; CEGMON being a popular choice CEGMON monitor. Patched to ensure all I/O is via the serial port only.