M100ROM

NEWS!

• Mike Stein has graciously released his board design through Oshpark so that people can get access to boards and build themselves a ROM adapter for Model 100!

Supported Models

• Model 100 only

About

The M100ROM adapter has several (fixed at assembly time) options:

 1 - Just convert non-standard pinout to standard JEDEC, to use a 256Kb (32KB) (E)EPROM in an old M100.
 2 - Same as #1, but using a 512Kb (64KB) (E)EPROM with an option ROM image in the upper half.
 3 - Same as #2, but without pinout conversion, for use in a 'new' M100.

If you have a 'new' M100 with the standard socket you can accomplish #3 with a simple 'shim' socket that goes between the system ROM socket and the EPROM and breaks the chip select connection, replacing it with a diode-and connection (with pull-up) to both the original system and the option ROM select signals and a connection to the '512's uppermost address line. The only added connection to the board is a clip lead to the ROM select at M5 pin 5.

Board

Schematic

Schematic was lost unfortunately.

How to Get One

The bare PCB can be ordered here:

 https://www.oshpark.com/shared_projects/Kil9S1ya

Cost is 7.50$ USD for 3 boards.

In addition, you need the following parts-

 2x 1N4148 diode or equivalent
 1x 10K 1/8W or 1/4W leaded resistor
 1x 27C256 or 27C512 (pre-programmed ideally)
 28x pins for connecting the module to the M100 ROM socket

Assembly

Installation

Installation

Installation of the hardware is a piece of cake.

Step 1

 Flip over the 

Step 2

 Replace the cover. 

Done!