ez80190 ZiLOG Semiconductor, ez80190 Datasheet - Page 136

• Manufacturer Part Number: ez80190
• Description: Ez80190 Microprocessor
• Manufacturer: ZiLOG Semiconductor

PS006613-0306
MACC RAM
MACC RAM Address Indexing
Retrieve A Calculation
The following procedure retrieves the results of a calculation.
1. Read the status register. If the Multiply-Accumulator has not completed the
2. If the DATA bank status is EMPTY and the CALC bank status is DONE, write
3. If both status fields indicate EMPTY, there is no result to retrieve.
4. If the DATA bank status is DONE, the application reads as many of the
The eZ80190 device features 1 KB of dual-port RAM available for use with the
Multiply-Accumulator, as illustrated in
appears as a 1 KB block of 8-bit RAM. To the Multiply-Accumulator, MACC RAM
appears as two blocks of 256 x 16-bit RAM. The CPU provides Read/Write access
to one port of the MACC RAM. The Multiply-Accumulator provides Read Only
access to the second port of the MACC RAM.
As described in
the CPU in the memory address space from {RAM_ADDR_U[7:0],
{RAM_ADDR_U[7:0],
received from the RAM Address Upper Byte register, RAM_ADDR_U. The MACC
X data is stored in the lower 512 bytes of the MACC RAM memory address space
from
MACC RAM memory address space from
byte, bits [7:0] of the 16-bit x and y data, is stored in the even memory addresses.
The most significant byte, bits [15:8], are stored in the odd memory addresses.
The data in MACC RAM must be stored in two’s-complement form.
For each calculation that the MACC is to perform, the software must arrange the
two vectors/arrays to be multiplied and accumulated. One vector must be written
previous calculation provided, the application must wait until the Multiply-
Accumulator completes the calculation, at which time the CALC bank status
changes to DONE.
80h
the DATA status becomes DONE.
MAC_AC0–3 registers as desired. Because the Multiply-Accumulator decodes
the A15:8 lines to determine when a transfer is complete, this register READ
can be initiated with an INI2R instruction. Reading the final byte of the result
changes the DATA bank status to EMPTY unless there is another result to
retrieve. If such is the case, the CALC bank status changes to EMPTY and the
DATA bank status changes to DONE.
DC00h
to the status register. As a result, the register banks are swapped so that
to
DDFFh
Random Access Memory
. The MACC y data is stored in the upper 512 bytes of the
DFFFh
PRELIMINARY
}. The upper byte of the MACC RAM address is
Figure
on page 57, MACC RAM is accessed by
DE00h
23. From the CPU, MACC RAM
eZ80190 Product Specification
to
DFFFh
. The least significant
Multiply-Accumulator
DC00h
} to
122