This in concept is very similar to Ralph Taggart's 'ROMscanner' device.
However, it's an update. The EPROM(s) have been replaced with larger capacity Flash Memory with the ability to program itself, not requiring chips to removed from the unit for an update or editing. The memory can be configured from a single 32Mb device to two 256Mb (32MB for a total of 64MB)
From a SSTV perspective it stores frames at 128x128 pixels with an 8-bit video depth, i.e 16,384 bytes each. With a single 32Mb (4MB) memory that's 256 SSTV frames. With 2x128Mb (2x16MB=32MB) yields 2048 SSTV frames. Someone check my math!
For NBTV, following Ralph's arrangement, say twice that amount in NBTV video frames, around 5-6 minutes of video, less sound. A rough outline is above...
With the worldwide chip shortage I've tried to make this as flexible as possible r.e. memory chips. More anon...just looking at local suppliers and those in the UK, lead times are into mid-next year...ho hum...
Also all Flash memory runs at 3.3V, or at least the majority, so this will be a 3.3V device, not 5V.
Steve A.
My math is a bit wobbly, I'll come back to it later...
Before I go much further I need to think about the operator interface with this unit, frame selection via rotary switches and the like are out...