Stack Int Erf Ac E; Stack Int Erf Ac E Connectors - Motorola MB68k-100 User Manual

68000 Motherboard User's Manual
7.15

Stack Int erf ac e

Functionality of the MB68k-100 motherboard may be expanded through its Stack
Interface. This interface is designed to support additional circuitry by providing access to
the internal buses and control signaling.
7.15.1

Stack Int erf ac e Connectors

The MB68k-100 offers two 0.1" pitch headers, each with 2x32 pins, that may be used to
interface with a stack of mezzanine daughter boards. The connectors have reference
designators CON160 and CON161. The connectors are positioned on opposite sides of
the motherboard, parallel along their long dimensions.
provided, CON162 and CON163. These are electrically pin-for-pin identical to the
former pair, respectively, and offer an additional opportunity for access. See Figure 12
on page 42 for a visual reference. See Table 19 and Table 20 for connector pin mapping.
The outermost pins on each side of each connector are connections to negative, ensuring
that the negative contact is made first in case of a hot insertion. This practice, however,
is not intended.
Table 19: Stack Connector CON160/CON162 Pin Map
Name Description
GND Supply Negative
VCC Supply Positive
M68K_AS !! 68000 Address
Strobe
M68K_LDS !!! 68000 Lower
Data Strobe
W/R ! Inverted 68000
Read/Write
DTACK_EXT !!!!!!!!! External
/DTACK input
M68K_BG !! 68000 Bus Grant
M68K_BR !! 68000 Bus
Request
HXCLK_OUT Symmetric
Discrete Clock
(Frequency/2)
CLK System Clock
M68K_HALT !!!! 68000 Halt
M68K_RESET !!!!! 68000 Reset
RST_PULSE Minimum One
Clock Cycle
Pulse on 68000
Reset Transition
from 0 to 1
Pin Pin Name
1 2 GND
3 4 VCC
5 6 M68K_UDS
7 8 M68K_R/W !
9 10 M68K_DTACK
11 12 AUTO_DTACK
13 14 M68K_BGACK
15 16 CLKIN
17 18 CLKDIVOUT
19 20 CLK !!!
21 22 HALT_CMD
23 24 RESET_CMD
25 26 RST_PULSE !!!!!!!!!
Page 39 of 54
Two additional headers are
Description
Supply Negative
Supply Positive
!!! 68000 Upper Data
Strobe
68000 Read/Write
!!!!!! 68000 Data Transfer
Acknowledge
!!!!!! On-Board Automatic
/DTACK output
!!!!!! 68000 Bus Grant
Acknowledge
Clock input
Symmetric Clock
Frequency Divider
Output
Inverted System
Clock
Input to Command
68000 Halt
Input to Command
68000 Reset
Inverted
RST_PULSE
Rev. A