Commodore 128 Programmer's Reference Manual page 634

624 COMMODORE 128
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DYNAMIC RANDOM ACCESS
MEMORY
This section discusses the characteristics of the C128 dynamic RAMs, which are
currently the 4164 64K-bit RAM. This RAM device is in the 64K by 1-bit configura- j j
tion. This section also contains information on the 4416 dynamic RAMs used by Lj
the 8563 video controller. This type of RAM is a 64K RAM in the 16K by 4 bit
configuration. \ j
SYSTEM RAM DESCRIPTION
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The C128 system contains 128K of processor-addfessable DRAM in the 64K by 1 (J
configuration, organized into two individual 64K banks. Additionally, the system
contains 16K of video display DRAM local to the 8563 video controller, not directly
accessable by the processor. \ I
RAM banking, described in detail in the MMU section in Chapter 13, is controlled ^
by several MMU registers: the Configuration Register, the RAM Configuration Regis- _
ter, and the Zero Page and Page One Pointers. Simply put, the Configuration Register j j
controls which 64K bank of RAM is selected; the RAM Configuration Register controls (J
if and how much RAM is kept in common between banks, and the Pointer Registers
redirect the zero and one pages to any page in memory, overriding the effect of the two ^ i
Configuration Registers. In the system, RAM bank select is achieved via gated CAS jj
control.
PHYSICAL CHARACTERISTICS Li
This section covers some of the characteristics of the 64K by 1-bit RAM and 16K by
4-bit RAM that are used in the C128 system. A pinout table and a figure are given for j
both the 4164 and the 4416 packages (See Tables 16-15 and 16-16 and Figures 16-23 and ^
16-24).