Meeprom

Meeprom (Molex EEPROM) is a version of Teeprom with a standard 27C256 pinout instead of the non-standard Tandy 100/102/200 pinout.

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PCB: OSHPark or PCBWAY

Source: http://github.com/bkw777/Teeprom

This is useful in at least the following machines:

TANDY Model 600

Kyotronic KC-85 (The only "Model T" with the Molex socket but a standard pinout!)

Epson PX-4

Epson PX-8

NOT for TRS-80 Model 100, 102, or 200!
For those, see Teeprom instead.

PCB ordering notes

On PCBWAY or JLCPCB there are several settings and options. Most you should leave as default, but there are a few settings to pay attention to.

Min Track/Spacing: 6/6mil
On PCBWAY the ordering page may come up with 5/5 or even 4/4 pre-selected, raising the cost unnecessarily. This board does not actually have any such narrow traces or gaps. All traces and gaps are 0.2mm minumum, which is almost 8mil, so 6/6 is the correct setting. Just manually select 6/6.

Surface Finish: ENIG
Not strictly necessary, and it raises the cost, but you want the castellated edge contacts to be gold plated.

Advanced options: Castellated Half Holes
Under advanced options there is a checkbox for castellated half holes. It raises the cost, and you don't really need this if you're willing to clean up any router mess yourself. But when placing the order the order will be reviewed by an employee and most of the time the reviewer will see the castellated edges and say it requires the option, or they may just add the option themselves and the. You may be able to argue with them by email to keep the option off, but probably it's not worth the fight.

OSHPark vs PCBWAY or JLCPCB
PCBWAY or JLCPCB produces a clean board outline routered all the way around and ready to use out of the box.
OSHPark boards have panelization attachment points that you will still need to sand down and clean up.
The flip side of the fact the OSHPark doesn't do any extra work to clean up the edges is there is also no extra charge for castellated edges.
The default DHL shipping from PCBWAY will deliver your boards in a few days, about a week total from order to doorstep. The cheaper options will take several weeks.
OSHPark boards are all always ENIG, not an extra charge, however the base service costs more, so in the end it's not that different.
JLCPCB is essentially the same as PCBWAY, except they don't have sharable project/buy pages like OSHPark or PCBWAY. You have to upload a gerber zip.

M4ROM

...aka Teeprom & Meeprom 2.0 aka the overkilling

Holds 4 rom images. Re-programmable with a programming adapter which you have to build, but actually costs less and is more convenient to use than a soic-28 test clip and wires.

There is both a TANDY-compatible version for Model 100/102/200, and a 27256-compatible version for everything else including TANDY Model 600 and Epson PX-8 etc.

https://github.com/bkw777/M4ROM

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