REX:flash: Difference between revisions

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:: boot sector / boot block
:: boot sector / boot block


There is no consistent way to search or for eliminate the remaining specs by part number pattern, because each manufacturer specifies these properties differently in their part numbers.
:There is no consistent way to search or for eliminate the remaining specs by part number, because each manufacturer specifies these properties differently in their part numbers.


2: For each potential part, you may have to search the exact part number on-line to find a datasheet for that part, to decipher the part number to find out if it matches all the specs.
:For each potential part...


* Ignore all parts that are not TSOP48 package. On most sites you can tell this at a glance from the picture without needing the datasheet.
2: Search for the datasheet for that part number. Find the legend that shows how to decipher the part number. Usually it's towards the end of the document. Using the part number legend...


* You need the datasheet to make sure the part is "bottom boot", or "top boot", or other like "flash file", or no boot
3: Verify the part is a TSOP48 package, standard pinout. (If there is no separate "reversed pinout" option, then the pinout is standard.)
: Most parts are either "bottom boot" or "top boot", and we need  "bottom boot"
: Search for the datasheet for the potential part, usually go to the end or near the end of the datasheet , and find the page that shows the legend for how the part number is constructed, and use that to decipher the part number you are looking at.


3: Any speed 90ns or faster is ok, but the slower the better, 90 is already much faster than the Model 100 operates at anyway, and generally old computers are crude devices and the digital signals on the bus are a bit noisy by todays standards, and it's possible for very fast chips to see the noise as data, because they actually operate that fast, while a slower chip is "blind" to high frequency noise. The Model 100 actually only needs abbout 200ns for it's ram and rom, but the specs from Steven Adolph for REX say 90ns. Maybe slower is actually ok, or maybe the CPLD on the rex itself needs the flash to be that fast even if the Model 100 doesn't. Most parts are 70ns and there is no reason not to just get that.
4: Verify the boot block is "bottom boot".


4: Any temperature range is fine. But you may opt for the extended temperature ranges if you want. You can ignore this part of the part number, or if you have a range of choices available, get whatever you want. But the standard, most common, cheapest "commercial" range (usually 0c to 70c) is fine.
5: Any speed 90ns or faster is ok, but the slower the better. (Old computers are crude and have a lot of noise on the bus, and fast parts can be fast enough to misinterpret some noise as data, while the noise is too high frequency to register as a valid pulse for a slower part. So slower is actually better than faster in this case.)


5: Other possible options like burn-in, packaging, etc you can ignore.
6: Any temperature range is fine. It doesn't hurt to get the more expensive industrial, automotive, or military temperature ranges, but the cheaper more common commercial range is fine.
 
7: Other possible options like burn-in, packaging, etc you can ignore.


==Some examples of compatible parts==
==Some examples of compatible parts==

Revision as of 04:53, 21 June 2019

Compatible flash chip for REX

The flash chip in the pre-loaded DigiKey cart may be out of stock because it is becoming obsolete.

The exact part in the cart is just one of several equivalent compatible parts that could be used in it's place.

There are several properties that you have to verify in order to find another part that is compatible.

You may have to search ebay or other suppliers for these parts.

The specs you need to meet are:

parallel flash memory
5 volt
single power supply / single voltage (same 5v used for reading and programming)
8 Mbit (1Mx8/512Kx16)
boot sector
bottom boot
TSOP48
90ns or faster

The generic part number series is "29F800", with different extra characters added depending on manufacturer.

To search for a compatible flash chip, follow this:

1: Start by searching for "29F800" on any supplier site like DigiKey, Mouser, ebay, Verical, etc, or just google.

That gets you all parts that meet most of the specs, and now you still need to check for a few more specs more manually.
All parts that have "29F800" in the part number should be:
flash memory
single power supply
5v
8Mbit x8/x16
boot sector / boot block
There is no consistent way to search or for eliminate the remaining specs by part number, because each manufacturer specifies these properties differently in their part numbers.
For each potential part...

2: Search for the datasheet for that part number. Find the legend that shows how to decipher the part number. Usually it's towards the end of the document. Using the part number legend...

3: Verify the part is a TSOP48 package, standard pinout. (If there is no separate "reversed pinout" option, then the pinout is standard.)

4: Verify the boot block is "bottom boot".

5: Any speed 90ns or faster is ok, but the slower the better. (Old computers are crude and have a lot of noise on the bus, and fast parts can be fast enough to misinterpret some noise as data, while the noise is too high frequency to register as a valid pulse for a slower part. So slower is actually better than faster in this case.)

6: Any temperature range is fine. It doesn't hurt to get the more expensive industrial, automotive, or military temperature ranges, but the cheaper more common commercial range is fine.

7: Other possible options like burn-in, packaging, etc you can ignore.

Some examples of compatible parts

Examples: 

Macronix
MX29F800*BT*-***
  MX29F800CBTI-70G‎
  MX29F800BTC-70

AMD
AM29F800BB-##E*
  AM29F800BB-70EC
  AM29F800BB-70EI
  AM29F800BB-70EK
  AM29F800BB-90EF
  AM29F800BB-55EC

STMicroelectronics
M29F800*B##N#
  M29F800AB90N1
  M29F800DB70N6

Fuji
MBM29F800BA-##PFTN
  MBM29F800BA-70PFTN
  
Motorola
*29F800*5*BT##
  M29F800A5KBT80

Part number legends for a few manufacturers


--------------------------------------------------------------------------

AMD
AM 29F 800B B - 70 E K
   |   |    |   |  | +- temperature
   |   |    |   |  +- tsop48
   |   |    |   +- speed
   |   |    +- bottom boot
   |   +- 8M, x8/x16, boot block
   +- flash, 5v

--------------------------------------------------------------------------

Macronix

MX 29 F 800 C B T I - 70 G
   |  | |   | | | |   |  +- rohs (may be absent)
   |  | |   | | | |   +- speed
   |  | |   | | | +- temperature
   |  | |   | | +- tsop
   |  | |   | +- bottom boot
   |  | |   +- revision
   |  | +- 8M, x8/x16, Boot Sector
   |  +- 5v
   +- flash, single ps

--------------------------------------------------------------------------

STMicroelectronics

 M 29 F 800D B 55 N 6
   |  | |    | |  | +- temperature
   |  | |    | |  +- tsop
   |  | |    | +- speed
   |  | |    +- bottom boot
   |  | +- 800A, 800D: 8M, x8/x16, Boot Block
   |  +- 5v
   +- flash

--------------------------------------------------------------------------

Fuji

MBM 29 F 800 B A - 70 PFTN
             |        + PFTN = tsop48, standard pinout
             +- bottom boot

--------------------------------------------------------------------------

Motorola

M 29F 800 A 5 K B T 80
| |   |   | | | | | +- speed
| |   |   | | | | +- tsop
| |   |   | | | +- bottom boot block
| |   |   | | +- temperature
| |   |   | +- voltage
| |   |   +- die revision
| |   +- density/config 8M x8/x16
| +- 29F = Single power supply
+- status M: motorola qualified
This cart is pre-loaded with quantities to build 3 REX boards.
Pick any version of the chip which matches this pattern:
AM29F800BB-##E*
Where:
## = Speed: 90 or faster (90 or less)
E = Package: Must be "E", which is TSOP
* = Temperature range code: Any
Examples:
AM29F800BB-70EK
AM29F800BB-90EF (except, that particular entry has a minimum order quantity of 98, at $6 per chip. So you can't use this link to buy 3 chips, but it shows how to identify a correct part. The datasheet for AM29F800BB shows that the 2nd B in "29F80BB" means bottom boot, and the E in "90EF" means TSOP48, And 90 is a good speed and the F temperature range doesn't matter to us.)
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