aiiadict{at}gmail.com wrote:
> 
> in the "FAQ" section (technical details):
> 
> 4. U4 and U11 are not normally populated. This is expansion space that
> I wired for a USB module and a GAL for glue logic. It can be used for
> some other interface too.
> 
> what are your plans for this?


With all the payed for cards in the mail I got back to the one I made
for myself and plugged in the DLP USB module

http://www.dlpdesign.com/usb/dlp-usb245mv15.pdf

assisted by a GAL16V8 as glue logic. Same could be done with several
TTL chips, but I prefer a single chip solution even if it needs to be
programmed. This combination worked right away with my extremely
simple "echo" test

	TXE	=	0xE2
	RXF	=	0xE3
	DATA	=	0xE0
	
	.org	0x100

testrd:	
	in	a,(RXF)
	rrca
	jr	c, testrd	; high means empty

	in	a,(DATA)
	out	(DATA),a	
	ld	c,a
	call	0xf539		;conout
	jp	testrd

So we have a very fast (1 megaBYTE per sec) communications channel
with a PC. With a 384 byte transmit FIFO Apple can do blind writes:
no way it can outrun USB. Not only is this channel very fast but there
is nothing to initialize.
On the PC side a serial driver can be used. Looks like a serial port
that just happens to work at *any* baud rate.


A number of uses come to mind:

1. The main purpose - a convenient way to exchange data with a PC.
Need some guru's help to make this port accessible as a CP/M "device".

2. Convenient debug output for a CP/M program.
3. A way to load the DOS 3.3 RAMDISK from a PC. If there are sources
for the code.
4. Very simple code loaded to the z80 will make this port available to
the 6502. The z80 code will just reroute data from it's address to USB
and back until 6502 resets the z80. Beats the heck out of SSC in speed.

-Alex.
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