ROM ROMs

ROM ROMs

Types of ROM Drives:
• ROM - mask (memory matrix) are programmed at the manufacturing stage.
• PROM - programmable ROMs are carried out on the basis of an IJ with fusible bridges made of nichrome.
• Series К500 К1500 КР556РТ.
• The user programs electrically, using the programmer of the RPZU to be programmable by the user.
• EPROM- with electric programming and UV erasing.
• EEPROM- with electrical programming and electrical erasure.
• SEEPROM (EAPROM) - with electrical programming and selective erasure.
• The common property of the MS ROM is a multi-digit (dictionary) organization, the main reading mode.

ROM structure with electrical programming


ROM designation


4 address lines give 256 memory locations

• If the MP system contains several memory modules, make up a memory card i. address space allocation.
• Address space - address bus width.
• Bit size 16 => 65536 number of addressable registers or PL.

ROM K155RE21-24 (ROM)
• Codes of letters of the Russian alphabet PE21 are recorded.
• Coded letters of the Latin alphabet PE22
• Coded arithmetic characters and numbers PE23
• Codes of additional characters PE24 are recorded.
• The MC aggregate forms a generator of 96 characters of the 7 × 5 format