VELA - Connecting to a microcomputer

Connecting the VELA to a microcomputer is relatively straightforward for any computer that possesses an interface with an eight bit user port with one or two control lines or similar. To that end, the VELA can be connected to a variety of 8-bit computers including the BBC Micro, Commodore PET, Commodore 64, a RM 380Z and with a suitable expansion card an Apple computer of the same period. The VELA could even be connected to an IBM-PC compatible computer with the relevant ISA card fitted.

The VELA connected to a BBC Micro and Oscilloscope

Once connected, using suitable software on the Microcomputer, the data from the VELA could be transferred for the purposes of long term storage on disc or cassette and manipulation by data analysis software such as VELAnalysis for the BBC Micro.

The VELA connected to a RM 380Z

RM 380Z photo ©Electronic System News 1983

The video below shows the VELA connected to my BBC Micro using the example data transfer program found in the Technical Manual which is also available for download from this site as an SSD disc image.

Connecting to a BBC Microcomputer

To connect the VELA to a BBC Microcomputer requires some of the pins of the VELA's digital out connection to be mapped to the BBC Micro's User Port. In total, 11 lines must be connected comprising of 8 data lines, 2 control lines and an earth.

The original cable with mapping PCB and connectors

An original VELA to BBC Micro cable mapping PCB

The photo to the right shows an original unused mapping PCB that was used in the construction of the cables manufactured by ISL as shown above. The PCB mapped a 26-way ribbon cable from the VELA to a 20-way ribbon cable that connects to the BBC Micro's User Port. Pin 1 of the VELA connects to the top left of the PCB and pin 1 of the BBC's User Port connects to the bottom right. The rest of the mapping is straightforward to follow using the table below.

VELA to BBC Micro User Port cable mapping table

Pin assignment Pin No. Pin assignment Pin No.
CA1 24 CB2 4
PB7 7 PB7 20
PB6 8 PB6 18
PB5 9 PB5 16
PB4 10 PB4 14
PB3 11 PB3 12
PB2 12 PB2 10
PB1 13 PB1 8
PB0 14 PB0 6
CA2 22 CB1 2
Earth 1 Earth 19

Connecting to a PC

With a suitable ISA card fitted to an IBM-PC compatible, the VELA was also able to transfer data to a PC using software called VelaCom.

ISA I/O card used to connect the VELA to an IBM-PC compatible

ISA I/O card photo courtesy of Robert Boyd (Glossop High School)

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If you've come across this page because you've found a dusty old VELA or any of the peripherals I've mentioned on the site in the store cupboard of the science department and you're wondering what you can do with it... You could always consider donating it to a good home such as mine where it would be reunited with a BBC Micro, archived for the future and used!

Although I now have many VELA related items, I am still missing many more bits and pieces so if you happen to have a VELA, any VELA software, manuals or related VELA handbooks, then I'd still be very interested in hearing from you so please do get in touch!

Of particular interest are any VELA SAM4 compatible modules and software for the RM380Z, Apple II and IBM-PC's of the day which currently are lost to the mists of time with the prospects of viable floppy discs containing the software being more remote as the years go by.

For a full list of VELA related items I'm looking for, please check out my VELA - WANTED, DEAD or ALIVE! page.