Godbout ECONOROM 2708
Introduction
This board provides space for up to 16 2708s, one of the most popular high density EPROMS. EPROMS give the advantage of retaining stored data when power is removed EPROMS are erasable; that is, after programming they may be erased and reprogrammed with other material. The EPROM locations on this board are grouped in four independent 4K blocks. The on-board DIP switch (no jumpers required) provides addressing on any 4K boundary. Additionally, each 4K block contains an independent disable switch. This board also features a wait state selection switch to select zero or one wait state, provision for use of PHANTOM (line 67), a switch addressed power-on-jump feature, thorough capacitor bypassing of supply lines to suppress noise transients, plus on-board regulation and heat-sinking for reliably cool operation. All this and presoldered sockets for all ICs go onto a double-sided, solder-masked printed circuit board with a complete component layout legend. This board provides the user with a highly flexible building block for virtually any S-100 system configuration. [1]
You can't really go wrong with the addressing, it's simple. You have four independent blocks A to D, which you can switch on or off individually.
Wait State
See 2nd switch down left, labeled WS.
If switch S6 is in the CENTER position, one wait state will be added to all memory cycles accessing this board. If the switch is in the DOWN position, no wail states will be added. [1]
Power on Jump
See 1st switch down left, labeled WS.
The power on jump feature, when enabled, causes the machine to start at some address other than zero after reset or power on clear. This is accomplished by driving the PHANTOM line low which should disable all system memory, then putting a jump command onto the data in buss, causing the CPU to jump to the desired address. This address can be any multiple of 256 by setting the high order byte of the address on the appropriate DIP switch (switch 9) This feature is enabled when slide switch 5 is in the CENTER (ON) position and is disabled when this switch is in the DOWN (OFF) position. [1]
I haven't tested it yet.
Tests
The MEMON/80 ROM is located at C000 and a test PROMs at D000, E000 and F000. All dumps are correct.
Repairing
Not necessary, but I had to move the switches and DIP switches dozens of times because the contacts were not made correctly, especially the blue DIP switches.
Internal Links
External Links
- S100 Computers: Godbout ECONOROM 2708
Technical Manuals
Others
- ...
References
- (↑) ECONOROM 2708, USER'S MANUAL, 1/1979