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. However an earlier version, without the extra vias for programming the device after manufacture, is here.

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!