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2.5
2.5.1
MEMORY
MODEL 465 - 64K DYNAMIC RANDOM ACCESS MEMORY BOARD
The 465 board is the dynamic memory card.
It contains 64K by 9 bits of
memory space.
The ninth bit in each byte is used as an odd parity check bit.
The board can be used as separate 16K banks.
CONFIGURING THE 465 BOARD
465 boards shipped in IMS systems will normally be configured to the system
requirements.
Phantom Line (Jack
TO)
The phantom signal is activated when the system is "booting-up".
When active,
this line disables all memory except the Intial Program Loader EPROM.
The
phantom line affects memory read operations only, not memory write operations.
When location JD is shunted, the phantom line is enabled.
This location is
etched for use in IMS systems.
If
this etch is cut, the phantom signal is
ignored by the rest of the system.
Enable 1.12 (Jack I B)
When the memory is used in the bank mode or for parity operations, jack JB
should be shunted so that the board can respond to I/O commands.
Normally, JB
is unshunted.
I/O Address Selection (Jack IC)
The selection of the board's I/O address is done on Jack JC.
The jack is labeled
0-7 (top to bottom) for the respective address bits (AO-A?) of the 1;0 address.
A "1" is programmed by removing a shunt.
Therefore, to program 1;0 address
OFH, the top four shunts (0-3) would be removed
("1'S")
and the bottom four
shunts (4-7) would be installed ("O's").
(Note that the "EN 1/0" shunt must be
on for the board to respond to the I/O command.)
Normally, all positions are
shunted.
CPU Selection (Jack IP)
The 8080 shunt (JE) should be installed for systems using 8080 CPUs.
F0r 2-80
systems, this shunt should be removed.
Front Panel (Jack IH)
If the 465 board is to be used with an "IMSAI" front panel, the shunt JH must
be in the right-most (FP) position.
"IMSAI" front panels are mainly used for
testing; in normal operation, this shunt should be in the leftmost position.
Memory Speed (Jack
1M
This shunt is dependent on the speed of the memory chips used, an"
~t
should
always be in the L position.
IMS International
5000 Series Microcomputers/7.0 1.83jPage 27
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