BUDDENBERGRA@USC-ISI.ARPA (Rex Buddenberg) (08/13/85)
I've heard nothing about S-100 boards, but at the MicroCornucopia SOC a couple weeks ago, Hiroshi Katayama was showing a single board computer which had so much on it that someone asked where the kitchen sink was... In addition to the stuff already mentioned was X.25 support (HDLC etc). Somebody mentioned Kaypro competition... It would fit in the lunchpail. b -------
RCONN@SIMTEL20.ARPA (Rick Conn) (08/13/85)
I'm working on an SB180 board (Steve Ciarcia's design) now. SUPER board. This 7 1/2" by 4" SBC has an HD64180, 256K bytes RAM, 2 RS-232C drivers, 1 parallel port, and a floppy disk controller for 3 1/2", 5 1/4", and 8" floppies. All running the Z System with a RAM disk. Clock speed is 6+ MHz. Note that by using the HD64180, the HD64180 ALONE has 64 I/O ports internally, providing 2 UARTs (RS-232C line drivers are off-chip), one clocked serial port, 2 timers/counters, 2 DMA controllers (mem-to-mem, mem-to-io, and mem-to-mem-mapped-io transfers), and a 12-level priority interrupt controller. Most impressive. Finally, the new Echelon ZAS assembler (a Z System tool) assembles the extended instructions for the 64180, and the ZDMH debugger helps debug, recognizing 64180 instructions. So there is a toolset to support 64180 development available now as well. Rick -------
RCONN@SIMTEL20.ARPA (Rick Conn) (08/14/85)
Hi, Ron, I'm afraid your rumors are true. The 64180 has an on-chip MMU which provides the memory management. This is accessed via on-chip I/O ports and the special set of 64180 I/O instructions. I haven't found this to be a problem yet. SW-wise, you init the MMU, defining the 64K memory banks to have 0, 1, or 2 common banks (common to all memory 64K memory banks) and 1 base bank (unique to each 64K memory bank). Switching banks is like loading a segment register, wherein you output any of the standard registers or (HL) to the MMU for the selection. The resolution of the common and base banks is to 4K, but that does not stop you from having a 63K+ TPA. I really like the 64180, but a problem came up last night which really bothered me. One of the two UARTS onchip (which I am using to connect to a Smartmodem) pays attention to the DCD line. You can sense this line internally thru a port. However, if DCD drops off (no carrier), then the Transmitter section of the UART is disabled! Ban news! No more comm to the Smartmodem for dialing the phone, answering the phone, hanging up the phone, etc. You can, of course, set the switch on the Smartmodem to keep DCD true (reverse logic, so 0 actually), but then you can't use DCD to detect loss of user signal. There is a way around this problem for the Ciarcia board, but I can't talk until Nov or so for reasons of confidence. Ciarcia will have a project on this option in Dec Byte. If Steve says I can talk earlier, I will. Rick -------