Memory Interface
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Transcript of Memory Interface
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Memory InterfaceA Course in Microprocessor
Electrical Engineering Dept.University of Indonesia
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ROM EEPROM SRAM DRAM
Jenis – jenis memori
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Pin Address Pin Data Pin Selection Pin Kontrol
Pin Memori
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Ilustrasi secara logika memori RAM 16 K x 8 (16 Kbyte):
Address 16 K
Ilustrasi fisik, memori RAM 16 K x 8 :
8 bit data
8 pin data
Pin kontrol
Address 16 K
Pin select
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Fungsinya:◦ Menghubungkan µP dengan > 1 memori◦ Mengatasi ketidakcocokan jumlah pin
(∑ pin µP > ∑ pin memori atau I/O) ex : 8088 (20 pin) dengan EPROM 2716 (11 pin)
Decoding Memori
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a. Decoder NAND Sederhana
Fungsi : jika pin mikroprosesor > pin memori, maka mikroprosesor hanya bisa mengakses sebanyak pin di memori, padahal yang terlihat oleh mikroprosesor sebanyak pin mikroprosesor, hal ini tidak konsisten sehingga memerlukan NAND Gate
Cara hubungan pin : pin mikroprosesor sebanyak jumlah pin memori dihubungkan langsung, sisanya dihubungkan ke NAND. Output dari NAND dijadikan select input
Contoh : EPROM 2K x 8 (2716)
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A0
A10
A11
A19
RD
Contoh : EPROM 2K x 8 (2716)
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8 Selection input
3 Enable input
8 output
Input dalam bit : C B AOutput sesuai konversi biner-digital:0 0 0 = 0 pin 0 aktif0 1 0 = 2 pin 2 aktif
Tipe 34LS138 adalah active low, sehingga pin yang aktif nilainya ‘0’, sedangkan yang tidak aktif diberi nilai ‘1’.
b. Dekoder 3-to-8 (34LS138)
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c. Dekoder 3-to-8 (34LS138)
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◦ Hubungkanlah 8 buah RAM yang masing-masing berukuran 32 K byte (32K x 8) ke mikroprosesor 8088 dan gambarkan rangkaiannya!!
◦ Jika alamat akses dimulai dari 00000H, berapa alamat akhirnya??
Contoh
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Hubungkan 16 buah ROM yang masing-masing berukuran 8 K x 8 ke mikroprosesor 8088. Jika alamat dimulai dari 40000H, berapa alamat akhirnya? Gunakanlah 1 buah decoder 2 to 4 dan 2 buah decoder 3 to 8.
Latihan