On Fri, 6 Mar 1998 00:50:19 +0000 (GMT) Tony Duell said:
Tim said about bit-rot
>> In the first stages of bit rot, single bits go "flaky" and will not
>> read reliably. So the first thing to do is read the 1702A's multiple
>> times and see if any are going bad in this way. Of course, be sure
>> to save the results of each read pass...
Tony replied with:
>With _most_ EPROMs, bit-rot causes 0's to turn into 1's, but not the
>reverse, since the fully erased (=discharged) state of the chip is full
>of FF's. Thus if you start to detect flakyness, you read the chip n times
>and logically AND the dumps. This is not hard to do given another
>computer, of course.
Tony, this didn't sound right to me so I looked it up and my book is
saying that 1702A (and the 5204) erase to all 0s. Is this wrong?
And I thought I'd pass along this neat table that I found on DataI/O
web page while looking for device code for my Series 22.
I reduced it on the xerox machine and taped it to my programmer.
DEVICE DECIMAL DECIMAL HEX HEX HEX
SIZE NO. BITS ADDR RANGE NO. BYTES CHECKSUM(1)
===========================================================================
2708 1K X 8 8K 0 ---- 3FF 400 3FC00
2716 2K X 8 16K 0 ---- 7FF 800 7F800
2732 4K X 8 32K 0 ---- FFF 1000 FF000
2764 8K X 8 64K 0 --- 1FFF 2000 1FE000
27128 16K X 8 128K 0 --- 3FFF 4000 3FC000
27256 32K X 8 256K 0 --- 7FFF 8000 7F8000
27512 64K X 8 512K 0 --- FFFF 10000 FF0000
27010 128K X 8 1M 0 -- 1FFFF 20000 1FE0000
27020 256K X 8 2M 0 -- 3FFFF 40000 3FC0000
27040 512K X 8 4M 0 -- 7FFFF 80000 7F80000
27080 1024K X 8 8M 0 -- FFFFF 100000 FF00000
2048K X 8 16M 0 - 1FFFFF 200000 1FE00000
4096K X 8 32M 0 - 3FFFFF 400000 3FC00000
8192K X 8 64M 0 - 7FFFFF 800000 7F800000
(1) Represents the checksum of a blank EPROM where memory locations contain
FF hex.
=========================================
Doug Coward dcoward_at_pressstart.com
Senior Software Engineer
Press Start Inc.
Sunnyvale,CA
Curator
Museum of Personal Computing Machinery
http://www.best.com/~dcoward/museum
=========================================
Received on Mon Mar 09 1998 - 17:27:35 GMT