aiiadict@gmail.com wrote:
On Nov 24, 7:40 pm, Steven Hirsch <snhir...@gmail.com> wrote:Neither the Applicard nor CardZ180 used DMA for transfer between host and guest processor. They both relied on programmatic transfer. For example, the Z80 writes a byte to a port and polls a status bit to see when it can write the next one. 6502 checks a status bit on its side and reads the byte from a memory address when it's ready.Yeah I'm reading more about the cards since this thread was posted... Even video data is transferred this way.... Did any of the z80 cards have their own video OUT connector? Seems like a really slllloooowwww way to go about updating the screen.
Vapor-ware wise, I found a diagram for a video piggyback board in a packet of stuff from the CardZ180 designer. I don't know if any hardware ever existed and I know that no software did.
More practically, the CardZ180 had two high-speed UARTs built in and could connect directly to a terminal or terminal emulator at 38.4K Baud. Ray Klein designed a nice UART piggyback board for the Applicard for the same purpose. There are a few of those in the wild.
BTW, the console output on a CardZ180 is about 2x faster than the Applicard due to both improved hardware and some optimizations to the transfer protocol. This is particularly noticeable on an accelerated IIGS or a //e with a 65C802 equipped Transwarp card. I wrote a host-side display driver that used the block transfer instructions on the 802 and 816 for more efficient scrolling. Even on a stock //e, screen performance was quite snappy.
The CardZ180 Z-System environment supported Bridger Mitchell's BackGrounderII software. This was a simple but powerful task switcher similar to Borland Sidekick (I'm dating myself now). A hot-key would freeze the foreground application and switch the console to BackGrounder's utility screen. You could switch between multiple live CP/M applications, although only one was actually active at a time. We could even save/restore high resolution text consoles on a Videx Ultraterm (132x55 text screen! Neat for word processing).
Steve