On Wed, 18 Nov 2009 10:46:36 -0800 (PST), lynchaj <***@yahoo.com>
wrote:
|On Nov 17, 11:27 pm, james <***@bud.u> wrote:
|> On Sun, 15 Nov 2009 13:22:52 -0800 (PST), lynchaj <***@yahoo.com>
|> wrote:
|>
|> |Hi! Does anyone have access to the Motorola EXORset schematics? If
|> |so, would you be willing to either make a scan or look something up
|> |for me?
|> |
|> |Thanks and have a nice day!
|> |
|> |Andrew Lynch
|> |================
|>
|> I would venture to say that the EXORset line of computers were
|> probably a single board approach, or as much of one as could, of the
|> older EXORCISOR system. Boy were those a beast. My guess is that many
|> of the same components in the EXORCISOR are apart of the EXORset.
|>
|> If my memory serves me correct the EXORset line was an attempt to make
|> a smaller single unit computer for the same market that were using the
|> beastly EXORCISOR units.
|>
|> james
|
|Hi James! I am building an IO mezzanine for the N8VEM 6809 host
|processor board. It will contain an ACIA, PTM, and two VIAs. The
|hardware prototype is working on my bench. One of my goals for the
|system is to fully support the ASSIST09 debug monitor. Motorola
|released the 6809 programming manual with the ASSIST09 source code.
|It contains references to a Motorola 6809 computer but is not specific
|as to which.
|
|The ASSIST09 debug monitor works OK on my prototype although the
|hardware assisted tracing is rather unreliable. I would like to find
|out how the MC6840 PTM timer #1 is interfaced to the 6809 CPU. Is it
|directly connected or passed through an inverter or some other logic
|or qualification? I presume Motorola is referring to the EXORset
|since it is their first 6809 computer released about the time of the
|6809 introduction.
|
|If anyone could help me with this design I would appreciate it.
|Thanks and have a nice day!
|
|Andrew Lynch
|=============
The EXORset was not the first release of a 6809 computer. There was a
6809 card that plugged into the EXORCISOR that came before the EXORset
if my memory serve me correct. I was working with EXORCISORs with 6809
CPU cards as far back as 1981. I believe the EXORset did not ship
until 1982 or 83 time frame. There was a single board computer that
Motorola was to release that never made it back in 1981/2 that had a
pile of chips on it. Included was a 6809CPU, 68488 GPIB controller,
6844 DMA chip, NEC765 Floppy controller, 2 PIA chips, 6845 CTRC, 64K
dram and 32K video dram, RTC, MC6860 modem chip and 20 bit parallel
port. Also had internal floppies and CRT and keyboard with Centronics
printer port. It was to be a single unit computer very similar to that
of the EXORset. Darn board is huge.
The 6840 is a tempermental device to work with. Remember that the
carry over from the 6800 computers writing to the PTM is that you
should not use read-modify-write instructions with the PTM. Instead
use strict read or store. The RW line is used as another register
select line.
On the M68MM17 board, the MC6840 has CS1 tied to VCC through a 3300
resistor. CS0 is used to select the chip from chip select logic based
on address mapping. A0 upto A2 tied to the RS0 to RS2 inputs. E and RW
went to their respective inputs and Pins 2,4,5,7,26, and 28 are pulle
to VCC via 10K reisistors.
hope this helps
james