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参数资料
| 型号： | DS1986-F5 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Programmable ROM |
| 英文描述： | 64K X 1 OTPROM, MADB2 |
| 封装： | MICROCAN-2 |
| 文件页数： | 24/27页 |
| 文件大小： | 548K |
| 代理商： | DS1986-F5 |
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DS1986
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EPROM STATUS BYTES
In addition to the 65536 bits of data memory the DS1986 provides 2816 bits of Status Memory accessible
with separate commands.
The EPROM Status Bytes can be read or programmed to indicate various conditions to the software
interrogating the DS1986. The first 32 bytes of the EPROM Status Memory (addresses 000 to 01FH)
contain the Write Protect Page bits which inhibit programming of the corresponding page in the 65536-bit
main memory area if the appropriate write protection bit is programmed. Once a bit has been
programmed in the Write Protect Page section of the Status Memory, the entire 32 byte page that
corresponds to that bit can no longer be altered but may still be read.
The next 32 bytes of the EPROM Status Memory (addresses 020 to 03FH) contain the Write Protect bits
which inhibit altering the Page Address Redirection Byte corresponding to each page in the 65536-bit
main memory area.
The following 32 bytes within the EPROM Status Memory (addresses 040 to 05FH) are reserved for use
by the iButton operating software TMEX. Their purpose is to indicate which memory pages are already in
use. Originally, all of these bits are unprogrammed, indicating that the device does not store any data. As
soon as data is written to any page of the device under control of TMEX, the bit inside this bitmap
corresponding to that page will be programmed to 0, marking this page as used. These bits are application
flags only and have no impact on the internal logic of the DS1986.
The next 256 bytes of the EPROM Status Memory (addresses 100H to 1FFH) contain the Page Address
Redirection Bytes which indicate if one or more of the pages of data in the 65536-bit EPROM section
have been invalidated by software and redirected to the page address contained in the appropriate
redirection byte. The hardware of the DS1986 makes no decisions based on the contents of the Page
address Redirection Bytes. Since with EPROM technology bits can only be changed from a logical 1 to a
logical 0 by programming, it is not possible to simply rewrite a page if the data requires changing or
updating. But with space permitting, an entire page of data can be redirected to another page within the
DS1986. Under TMEX a page is redirected by writing the one’s complement of the new page address into
the Page Address Redirection Byte that corresponds to the original (replaced) page. This architecture
allows the user’s software to make a “data patch” to the EPROM by indicating that a particular page or
pages should be replaced with those indicated in the Page Address Redirection Bytes. To leave an
authentic audit trail of data patches, it is recommended to also program the write protect bit of the Page
Address Redirection Byte, after the page redirection is programmed. Without this protection, it is still
possible to modify the Page Address Redirection Byte, making it point to a different memory page than
the true one.
If a Page Address Redirection Byte has a FFH value, the data in the main memory that corresponds to that
page is valid. If a Page Address Redirection Byte has some other hex value than FFH, the data in the page
corresponding to that redirection byte is invalid. According to the TMEX definitions the valid data can
now be found at the one’s complement of the page address indicated by the hex value stored in the
associated Page Address Redirection Byte. A value of FDH in the redirection byte for page 1, for
example, would indicate that the updated data is now in page 2. The status memory is programmed
similarly to the data memory. Details for reading and programming the EPROM status memory portion of
the DS1986 are given in the Memory Function Commands section.
The Status Memory address range of the DS1986 extends from 000 to 1FFH. The memory locations 60H
to 0FFH and 200H and higher are physically not implemented. Reading these locations will usually result
in FFH bytes. Attempts to write to these locations will be ignored.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1986-F5# | 功能描述:iButton RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated |
| DS1986-F5+ | 功能描述:iButton RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated |
| DS1986U | 制造商:未知厂家 制造商全称:未知厂家 功能描述:UniqueWare iButton |
| DS1990 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Serial Number iButton |
| DS1990A | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Serial Number iButton |
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