1-6. Performance Specifications - Type 2 System Board - IBM Personal System/2 50 Technical Reference

The Type 2 system board supports two speeds of system board
memory. Cycle times differ depending upon the speed. See
Figure 3-7 on page 3-11.
DeYlce
Mlcroproceaaor (10 MHz - 100 ns Clock):
Access to System Board RAM:
85-ns Memory
120-ns Memory
Access to System Board ROM
Access to Channel:
Default Transfer Cycle:
110
Access
Memory Access
Synchronous Extended Transfer Cycle
Refreah Rate
(Typically performed every 15.1 jls)
Bua Master Accesa to System Board RAM
DMA Controller (10 MHz - 100 na Clock):
Number
of
Walta
o
1
1
o
Single Transfer:
300
+
110
Access
+
Memory Access
Burst Transfers: 300
+
(110 Access
+
Memory Access)N •
System Board Memory Access
85-ns Memory
120-ns Memory
Default Transfer Cycle:
110
Access
Memory Access
Synchronous Extended Transfer Cycle
• N is the number of transfers in the burst.
Cycle
Time (na)
200
300
300
300
200
300
500 (min)
300 (min)
200
300
300
200
300
Figure 1-6. Performance Specifications - Type 2 System Board
1-8 Model 50 System Overview