A fork of Grant Seale's https://twitter.com/zx80nut great work for emulation of Compukit UK101 on FPGA https://www.youtube.com/watch?v=0S_cR3xW2UU downloaded from UK101 page http://searle.hostei.com/grant/uk101FPGA/index.html
UK101 is used as the base for emulating ORAO computer on FPGA.
More info on ORAO wiki
ORAO was created as an upgrade of GALEB with 256x256 bitmap graphics framebuffer and more RAM. GALEB has been also known as YU101. YU101 was similar to UK101.
Most comfortable loading of bitstreams from SD card is done with Onboard ESP32 OSD loader.
The emulator generates PAL 50Hz composite video signal using simple mixer with 2 resistors:
SYNC pin -- 1 k -- composite video
VIDEO pin -- 470 ohm -- composite video
It can be displayed on TV with composite input (yellow cinch) or projectors.
ULX2S FPGA board has already video mixer with suitable resistors that outputs video signal to left channel (tip) of 3.5mm stereo jack. With a suitable cable it can be connected directly. Yellow connector is usually for video.
ULX2S also has has several push buttons which can be used to enter BASIC.
For some better typing experience, PS/2 keyboard can be connected. Although rated for 5V, most PS/2 keyboard will work with 3.3V supplied from FPGA board. CLK and DATA need 1k pullup resistors:
PS/2 ULX2S ULX2S
---- -----
CLK pin 8 -- 1k -- 3.3V pin 25 or 48
DATA pin 9 -- 1k -- 3.3V pin 25 or 48
GND pin 1 or 24
VCC pin 25 or 48
To compile original UK101 for TB279 board (Altera Cyclone-4) Prerequisite: Altera Quartus-II (I have 13.0sp1) and then
cd proj/altera/uk101_tb276_bram
make
make program # upload to FPGA RAM
make flash # upload to config flash
It compiles but I haven't actually tested it :)
For quickstart flash the bitstream:
cd proj/lattice/uk101_64x32_ulx2s_sram
unzip UK101-64K-64x32-ULX2S-8E.zip
ujprog -j flash UK101-64K-64x32-ULX2S-8E.jed
On next power up board will become UK101
To compile UK101 with 64K RAM (BASIC reports 40K free) and 2K extended screen size of 64x32 chars for ULX2S board (Lattice XP2). Prerequisite: Latice Diamond (I have 3.4)
cd proj/lattice/uk101_64x32_ulx2s_sram
make
make program # upload to FPGA RAM
make flash # upload to config flash
To enter BASIC: After reset it will prompt
Press C (right button)
Press ENTER (middle button) twice
On screen:
CEGMON (D/C/W/M) <press c>
MEMORY SIZE? <press enter>
TERMINAL WIDTH? <press enter>
40191 BYTES FREE
C O M P U K I T U K 1 0 1
Personal computer
8K Basic Copyright1979
OK
For quickstart flash the bitstream:
cd proj/lattice/orao_ulx2s_sram
unzip ORAO-103-32K-ULX2S-8E.zip
ujprog -j flash ORAO-103-32K-ULX2S-8E.jed
On next power up board will become ORAO 103
To compile ORAO with 32K RAM (BASIC reports 23K free) and 8K graphics screen size of 256x256 pixels for ULX2S board (Lattice XP2) Prerequisite: Lattice Diamond (I have 3.4)
cd proj/lattice/orao_ulx2s_sram
make
make program # upload to FPGA RAM
make flash # upload to config flash
To enter BASIC After reset it will prompt *_ (underscore cursor blinking).
Press B (left button)
Press C (right button)
Press ENTER twice (center button)
It will start BASIC
on screen:
*BC_ <press enter>
>EAGLE< EXTENDED BASIC
V 1.0 (C) 85
MEM SIZE? _ <press enter>
23534 BYTES FREE
_
For loading some file into ORAO RAM using ESP32 at ULX3S board, read this ESP32 ORAO SPI RAM loading
It works on XC6SLX25 based board with HDMI output connected over HDMI-DVI connector to monitor. Haven't tested with true HDMI input device.
It actually displays 256x240 pixels, bottom 2 text lines currently not visible.
Should work the same on smaller FPGA like XC6SLX9 (untested).
Here is listed of boards what is verified that works.
The board, does it compile, and what video output it can generate.
Many vendor specific modules have been re-written into generic VHDL or VERILOG to ease effort when porting to other FPGA boards. If some feature for some board is not listed it probably can be supported with some programming and testing, contributions are very welcome :-).
VGA and HDMI code is now unified, so same code is generating both video formats. If something does VGA it could also do HDMI and vv.
UK101
| board | compiles | Composite | VGA | HDMI |
|---|---|---|---|---|
| ULX2S | YES | YES | YES* | |
| TB276 | YES |
ORAO
| board | compiles | Composite | VGA | HDMI |
|---|---|---|---|---|
| ULX2S | YES | YES | YES* | |
| SCARAB | YES | YES |
- board can generate VGA signal but needs external connector or breakout board and few resistors
CEGMON manual: http://www.osiweb.org/manuals/cegmon.pdf
UK101 manual http://www.compukit.org/images/8/8e/Compukit-manual.pdf
Orao Emulator (Perl) http://svn.rot13.org/index.cgi/VRac
Orao Emulator (Pascal) http://www.deltasoft.com.hr/retro/oraoemu.htm
Orao Emulator (SAM) https://github.com/simonowen/oraoemu