12672Re: The 1802 Elf and Serial EEPROMs
- Mar 3, 2013--- In firstname.lastname@example.org, "jdrose_8_bit" <rarecoinbuyer@...> wrote:
>Well several things... In PE style for the Elf, latching the address for more space was one of the simple things to do. so that can be settled.
> I am gathering the parts to build a PE type 1802 Elf for testing the 1861 replacement circuit. Instead of manually toggling the Spaceship code and bitmap into the Elf I would like to burn it into a 256 x 8 bit ROM of some sort.
> I cannot find any current parallel 256 byte EEPROMs but I have found some serial EEPROMs like the Microchip 24LC02B-E/P. I think I understand how they work. Plus they are very cheap and small.
> Would it be difficult or possible to use one of these 256 byte 8 pin DIP serial EEPROMs as a ROM for an Elf computer? Or perhaps recommend a 256 byte parallel EEPROM (current or obsolete)?
> Sorry for the simpleton questions. I am basically new to the hardware side of computers.
As to serial EEproms, yes its doable. The yabut is that you need a program to do the bitbash IO and that would still have to be toggled in and isn't going to be super small. The output line would be Q and the input is one of the unused EF lines. If Q is used for terminal or
other then a output port could be configured and used.
I have interfaced those serial eproms to a lot of machines and I lean to the bigger (more bits) parts when I do as once you do the interface code size is a handy thing.
If you extend the address it's fairly easy to find 8k and larger parallel EEproms.
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