STPC STMicroelectronics, STPC Datasheet - Page 28

• Manufacturer Part Number: STPC
• Description: PC Compatible Embeded Microprocessor
• Manufacturer: STMicroelectronics

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STRAP OPTION
Note;
1) This Strap Option selects between two different
functional blocks, the first is the ISA (SMEMW#)
and the other is the VGA block (Color_Key).
2) Setting of Strap Options MD [2:15] have no ef-
fect on the DRAM Controller but are purely meant
for software issues. i.e. Readable in a register.
3.1 STRAP REGISTER DESCRIPTION
3.1.1
(STRAP0)
Bits 7-0 of this register reflect the status of pins
MD[7:0] respectively. They are expected to be
connected on the system board to the SIMM con-
figuration pins as follows:
Note that the SIMM speed and type information
read here is meant only for the software and is not
used by the hardware. The software must pro-
gram the Host and graphics dram controller con-
figuration registers appropriately based on these
bits.
This register defaults to the values sampled on
MD[7:0] pins after reset.
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Memory
MD38
MD39
MD40
MD41
MD42
MD43
Lines
Data
Bit Sampled
STRAP
Bits 6-5
Bits 3-2
Bits 1-0
Note
Bit 7
Bit 4
Refer to
REGISTER
CPU
-
-
-
-
-
SIMM 0 dram type
SIMM 1 dram type
SIMM 0 speed
SIMM 1 speed
Description
0
Reserved
Designation
INDEX
CPU Mode
Reserved
Reserved
Reserved
Reserved
Reserved
4AH
Issue 1.2
Location
3.1.2
(STRAP1)
Bits 7-0 of this register reflect the status of pins
MD[15:8] respectively. They are expected to be
connected on the system board to the SIMM con-
figuration pins as follows:
Note that the SIMM speed and type information
read here is meant only for thesoftware and is not
used by the hardware. The software must pro-
gram the Host and graphics dram controller con-
figuration registers appropriately based on these
bits.
This register defaults to the values sampled on
MD[15:8] pins after reset.
3.1.3
(STRAP2)
Bits 4-0 of this register reflect the status of pins
MD[20:16] respectively. Bit 5 of this register reflect
the status of pin MD[23]. Bit 4 is writeable, writes
to other bits in this register have no effect.
They are use by the chip as follows:
Bit 4-2; Reserved
-
-
-
-
-
Bit Sampled
STRAP
STRAP
Bits 6-5
Bits 3-2
Bit 7
Bit 4
User defined
Actual
Settings
Pull down
Pull down
Pull up
Pull up
Pull up
REGISTER
REGISTER
Set to ’0’
SIMM 2 dram type
SIMM 3 dram type
SIMM 2 speed
SIMM 3 speed
DX1
Description
1
2
-
-
-
-
-
INDEX
INDEX
Set to ’1’
DX2
-
-
-
-
-
4BH
4CH