Designing the RhoCoCo Retro Home COlor COmputer hardware: Difference between revisions
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'''Rhococo Retro Home COlor Computer''' | '''Rhococo Retro Home COlor Computer''' | ||
Is a retro version of the | Is a retro version of the Sinclair spectrum, but not based on a Z80, but on an ARM7TDMI based simple micro-controller, (probably an STR710FZ2) running at 66MHz with 256 + 16 KB internal fast Flash and with 64K internal fast RAM and a separate external 32K VRAM. | ||
It will be capable of 320x200 VGA full high resolution graphics 16 colour display (Mode "D" timings, 70Hz, Horizontal Sync = 31.778 KHz, pixel clock 25.175 MHz). | |||
To be able to keep the design simple, but still able to be used with a VGA monitor, I chose to support only the VGA lowest resolution with 16 colours. It means we only need to have a 256000 bit (32K) frame buffer. | |||
The display logic will be designed to read out four bytes (a 32 bit "word") in the time assigned to eight consecutive pixels, three bytes will be shifted to the Red, Green an Blue colour inputs, and one to the intensity input, giving sixteen colours per pixel. Preferably the "glue logic" for it will consist of standard logic, but if necessary I will consider a small FPGA. | |||
the Rhococo will support a simple SD-Card interface as storage, and will use a keyboard similar to the ZX81+34, but with more keys,and a more conventional keyboard layout. | |||
For sound the ARM chip will offer a PWM output. | |||
Revision as of 21:57, 20 January 2015
Rhococo Retro Home COlor Computer Is a retro version of the Sinclair spectrum, but not based on a Z80, but on an ARM7TDMI based simple micro-controller, (probably an STR710FZ2) running at 66MHz with 256 + 16 KB internal fast Flash and with 64K internal fast RAM and a separate external 32K VRAM.
It will be capable of 320x200 VGA full high resolution graphics 16 colour display (Mode "D" timings, 70Hz, Horizontal Sync = 31.778 KHz, pixel clock 25.175 MHz).
To be able to keep the design simple, but still able to be used with a VGA monitor, I chose to support only the VGA lowest resolution with 16 colours. It means we only need to have a 256000 bit (32K) frame buffer. The display logic will be designed to read out four bytes (a 32 bit "word") in the time assigned to eight consecutive pixels, three bytes will be shifted to the Red, Green an Blue colour inputs, and one to the intensity input, giving sixteen colours per pixel. Preferably the "glue logic" for it will consist of standard logic, but if necessary I will consider a small FPGA.
the Rhococo will support a simple SD-Card interface as storage, and will use a keyboard similar to the ZX81+34, but with more keys,and a more conventional keyboard layout.
For sound the ARM chip will offer a PWM output.