Excalibur 64 The Recreation

Description

The '''Excalibur 64''' was a kit computer released by the now defunct Australian company BGR Computers. Sold as a kit it was first advertised in the magazine Electronics Australia's July 1983 edition. There are not many left in the wild. Fortunately the schematics and ROMs have been saved. This project is an attempt to rebuild this computer. Rules are, no FPGAs or microcontrollers to be used. All ICs are available from various sources. There are some quality of life inclusions. Replaced the DRAM with one SRAM and swapped out the 2764 EPROMs with a 39SF010.

Details

The '''Excalibur 64''' was a kit computer released by the now defunct Australian company BGR Computers. The Excalibur 64 sold from July 1983 to August 1984.

BGR Computers was established January 1983 with the intent of developing a system similar to the MicroBee to get a foot hold in both the educational and business markets. The company at time wanted to develop a complete system but the costs of development and availability of software made this prohibitive. Therefore, to enter the fledging home computer market BGR engaged an independent design company to develop a diskless kit which was first advertised in the magazine Electronics Australia's July 1983 edition.

More that 300 kits were sold and with the help of user groups the software catalogue grew and included, games, utilities and educational programs.

By December 1983 the Excalibur 64 was released as a complete system the sales price jumped from $399 to $699 but was fully built and tested. This price did not include a monitor and a disc controller board that could run up to four 5 ¼ or 8-inch drives would cost a further $299.

The idea of this project is to get to close as we can get the the fifth and last version of the Excalibur 64. Then add the peripherals, first a port expansion board and then a FDD controller. The controller will only accommodate 2 x 5 1/4" drives not the 8" drives.

Oh! and a nice case ... eventually.

Files

pcb-top.png

Image of a real Excalibur 64 bare PCB. Unfortunately not mine :(

Portable Network Graphics (PNG) - 2.89 MB - 04/11/2026 at 04:15

Preview

pcb.png

Screengrab from the MAME emulator. Looks like the address decoding and part of the DRAM

Portable Network Graphics (PNG) - 218.82 kB - 04/11/2026 at 04:14

Preview

excalibur.png

Screengrab from the MAME emulator detailed CAD drawing of the Excalibur 64 with keyboard and monitor

Portable Network Graphics (PNG) - 53.65 kB - 04/11/2026 at 04:13

Preview

closeup.png

Screengrab from the MAME emulator, showing off the 'hires'

Portable Network Graphics (PNG) - 993.00 kB - 04/11/2026 at 04:13

Preview

booty.png

Portable Network Graphics (PNG) - 169.12 kB - 04/11/2026 at 04:12

Preview

Components

1 × Z80 Microprocessors

1 × MC6845 CRTC Controller

1 × 8253 Programmable Interval Timer 3 Mhz

1 × 8251 Programmable Communication I/O

1 × 8255 Programmable Peripheral I/O

Project Logs

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Video board 1 of 2
Dave • 6 hours ago • 0 comments

CRT board done, this contains the MC6548 CRTC, SRAM and Character ROM. Provides the dot data and colour data to the video_RF board, which is next.
New (old) chips
Dave • a day ago • 0 comments

Just got a bunch of ICs from a fellow Hackadyer ( is that the right term?). He sent me 8251 UART, 8253 TIMER, 8255 PIO, Z80 DMA, 6522 VIA, AY-50-1015 UART, Z80 DART and 6845 CRTC. Thanks :) and will test and put to good use.
Side quest - run some programs using MAME
Dave • 6 days ago • 0 comments

While this project is about the recreation I have added some screengrabs using MAME. These are all images loaded up with MSBASIC. The booty one is particularly interesting as it has colour. There more but some are too rude, even at 320x200 monochrome.
Progress updates
Dave • 04/05/2026 at 12:24 • 0 comments

Currently it has working, audio and serial and parallel ports. It has a monitor ROM so I can do basic tests and more importantly transfer test programs without having to burn the EEPROM all the time. I have since learnt about the OneROM project on GitHub would have used that if I knew earlier. Oh well I now have some ready for the next project.

Also in this picture is a real Excalibur 64 keyboard kindly donated by an owner of a couple of machines and had and extra keyboard.

Next step is getting the video going. This is going to be the hardest bit, so have split the video into the processing side which includes the 6845 CRTC, SRAM and other bits to process the colour and dot data. A second board will take this data and serialise it for RGB ( I think its a form of EGA ? ), composite video and maybe even RF. Probably steal a RF modulator from a old C64 board for that.

View all 4 project logs

Discussions

Dave wrote 04/08/2026 at 23:09

Hi Howard thanks for your comment. Must say I'm jealous, have only known of two machines out in the wild and I don't think they work either. If you ever do get it out please let me know. As a side project I am documenting the history and gathering any info I can on Excaliburs that still exist. And if you do want to get it going please reach out. Happy to help, I have quite a few spare bits and learnt a lot on how this system works.

Are you sure? yes | no

Howard wrote 04/08/2026 at 19:54

Hi, just stumbled across your project in an email I just received. Looking forward to following along on the journey. I built my Excalibur 64 when it was first released as a kit. Unfortunately, it is not operational, but I was reluctant to let it go so still have it stashed away. Maybe it is time to get it out and see if it is salvageable.

Are you sure? yes | no

Excalibur 64 The Recreation

Description

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