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expand chips tested list in docs

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Tom Nisbet 2022-12-12 18:05:27 -05:00
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docs/prom-families.md
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@ -152,7 +152,7 @@ The 8755 build of TommyPROM also has a circuit to control the 25V programming pu
|:--- |:--- |:--- |:--- |:--- | |:--- |:--- |:--- |:--- |:--- |
|AT28C256 |Atmel, others|EEPROM |28C |Fully supported| |AT28C256 |Atmel, others|EEPROM |28C |Fully supported|
|SST39SF040|Microchip |Flash |SST39SF|All SST39SF0x0 supported| |SST39SF040|Microchip |Flash |SST39SF|All SST39SF0x0 supported|
|WE27E257 |Winbond |EEPROM |27 |Continual 12V or 14V for program/erase| |WE27C257 |Winbond |EEPROM |27 |Continual 12V or 14V for program/erase|
|AT29C010 |Atmel |Flash |28C |Only with 128 byte or less sector size| |AT29C010 |Atmel |Flash |28C |Only with 128 byte or less sector size|
|8755A |Intel |EPROM |8755A |Requires 25V pulses to program| |8755A |Intel |EPROM |8755A |Requires 25V pulses to program|
@ -178,12 +178,15 @@ writing new data. The code keeps track of the current sector and will automatic
an erase operation whenever a write starts to a new sector. The _Erase_ command is an erase operation whenever a write starts to a new sector. The _Erase_ command is
supported, but is not needed unless overwriting new data to a single sector. supported, but is not needed unless overwriting new data to a single sector.
#### 27E257 #### 27C257
The Winbond WE27E257 and WE27C257 appear to be identical 32Kx8 EEPROMs. These have a The Winbond WE27C257 and WE27E257 appear to be identical 32Kx8 EEPROMs. The 27C version
_VPP_ pin that needs a constant 12V during programming. Unlike the newer 28C EEPROMs, has been tested.
these chips do not automatically erase before writing to a location. Instead, the
entire chip is erased by applying 14V to _VPP_ and _A9_ and then pulsing _CE_. These EEPROMs have a _VPP_ pin that needs a constant 12V during programming. Unlike the
newer 28C EEPROMs, these chips do not automatically erase before writing to a location.
Instead, the entire chip is erased by applying 14V to _VPP_ and _A9_ and then pulsing
_CE_.
Because the chips use a constant high voltage for programming instead of a pulse, an Because the chips use a constant high voltage for programming instead of a pulse, an
external power supply and two diodes can be used to supply either 5V or 12V to the external power supply and two diodes can be used to supply either 5V or 12V to the