On 4/24/07, Allison <ajp166 at bellatlantic.net> wrote:
I'd simplify diskette controller to mass storage
(any form).
I had more of a solid-state 'disk' in mind, anyway (SD, CF, etc.) If
I'm going to twiddle floppies, I'll just fire up a Kaypro. I might
also consider a TU58 emulator running from a modern PC, attached via
the B-channel of a Z8530 SIO. This exercise is more about the Z-80
and CP/M than about designing/implementing a floppy controller.
>> > A video card will chew up valuable RAM,
and many of them are only 16x64,
>> > but it does let you do real-time screen updates, games etc.
the logic for rolling your own VDM1 equivalent is 1K
of ram in the
address space and a screen refresh (H and V timing, line counters)
are about 10 or so TTL pieces. It's actually simple if you do not
have to build a S100 bus interface.
If that's the case, I'd probably consider a 6845 - I'm familiar with
the chip from the 8032 PET, and I know they aren't hard to find. For
now, though, I'm still going to stick with a UART and terminal.
You can copy the screen logic for TRS80 as that is a
basic 64x16 as well.
Good thing to keep in mind.
-ethan