Hello Chummies
Well I felt in the mood for a laugh today and I have been threatening zetr0 to post pix of this beastie someday.....
Back in 1985, When the PIC and FPGA's were still in peoples dreams...
I needed a "Microcontroller", as you all know about my fascination for Acorn BBC micros, in those days it was all about 6502 Machine code for me.
I designed the following "Mini Beeb" to replicate the User port of the Beeb & also provide a full I/O 2nd user port in place of the Beeb's printer port which is only uni-directional due to the Latch buffer.
It has a Mighty 2KB of RAM & 2KB of ROM & a good ole 6522 VIA being driven by a 2MHz 6502A CPU.....
Reset Latch & single +5V supply.
So using the Beebs built in assembler to 'offset compile' & develop the user hardware from the Beebs real ports, you could then program the firmware tested & debugged on the beeb onto an eprom & then simply replace the Beeb with my board..... There was a timing factor involved but I cannot remember it now as I had code written to take that into account as the 'Mini Beeb' would actually run faster than it's big brother as there was only the 6522 to interupt the 6502......
By the way the PCB layout was done using Pineapple's PCB Design which was running on a Beeb too... Double sided as well
It was crude but these days I would use a PIC controller....
Enjoy & have a laugh, but please be kind......
TC
Well I felt in the mood for a laugh today and I have been threatening zetr0 to post pix of this beastie someday.....
Back in 1985, When the PIC and FPGA's were still in peoples dreams...
I needed a "Microcontroller", as you all know about my fascination for Acorn BBC micros, in those days it was all about 6502 Machine code for me.
I designed the following "Mini Beeb" to replicate the User port of the Beeb & also provide a full I/O 2nd user port in place of the Beeb's printer port which is only uni-directional due to the Latch buffer.
It has a Mighty 2KB of RAM & 2KB of ROM & a good ole 6522 VIA being driven by a 2MHz 6502A CPU.....
Reset Latch & single +5V supply.
So using the Beebs built in assembler to 'offset compile' & develop the user hardware from the Beebs real ports, you could then program the firmware tested & debugged on the beeb onto an eprom & then simply replace the Beeb with my board..... There was a timing factor involved but I cannot remember it now as I had code written to take that into account as the 'Mini Beeb' would actually run faster than it's big brother as there was only the 6522 to interupt the 6502......
By the way the PCB layout was done using Pineapple's PCB Design which was running on a Beeb too... Double sided as well
It was crude but these days I would use a PIC controller....
Enjoy & have a laugh, but please be kind......
TC
