NoCan2, the 16550 version
Presented by:
Only On Saturday Night
Flash:
Tuesday, June 1, It booted NitrOS-9, in the 4MHz mode, from RS-DOS. Used
daily in the 4MHz mode. The "4MHz" frequency that is spliced in, is actually
about 4.77MHz. The "4MHz" throughput is still about 4MHz, no different
than SockMaster.
The NoCan2 board has:
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2-megs of memory, fully useable for OS9 or NitrOS-9.
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Uses 3 or 8 or 9 chip simms, doesn't care.
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Auto-Refreshing of the SIMM's.
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4MHz, can be turned off if not needed or wanted.
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For 63x09E's only. Doesn't seem to work with 68x09E's.
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Probably will not work in the 4MHz mode with any 32MHz crystal hack.
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The Lattice chip will work up to 80MHz.
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The bottleneck is the CPU.
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1 serial, a 16550. Actually, 8250, 82C450, 16450, 16550's have been tried.
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1 parallel, a 6821 PIA, wired as a printer port.
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Full CPU address & R/W buffers,74ACT family.
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The buffers connect back to the coco-3 and to the coco-3 game slot, and
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E & R/W are buffered separately on this board.
6821:
Is set up like a printer port. Use the /PiaPak driver and /Lpt1 descriptor,
or you can write your own drivers. Has a DB-25 cable header, for a DB-25F
connector, just like a PC. It can be used as a bi-directional 8-bit port,
with the appropriate software.
16550:
The 6821 has jumpers to select either $FF6X or $FF7X, while the 16550
has jumpers to select either $FF1X or $FF3X address range. I have no buffered
software drivers for this 16550 serial port chip, don't ask. I do have
a very crude serial port driver and descriptor. Reads or writes a byte
at a time, no interrupts acknowledged, tested with 8250, 82C450, 16450,
16550 chips.
4MHz:
For the 4MHz, there are headers for green and yellow low-power LED's
(suggested colors). One LED lights up when it's in the POKE &HFFD9,0
(fast) mode, other LED lights up when it is actually running the 4MHz.
Also, there's a 2-pin header for the external switch that the user can
toggle, turning 4MHz on or off.
NoCan, the name comes from the
idea that some folks have removed their RF metal-can and therefore would
be able to use this board with shorter connections, ie. shorter pins.
This page updated: 1999/11/16
