CompuPro - ECONOROM 2708
This was Godbout's second EPROM board
following on from the original ECONOROM (which only took 5204 EPROMS).
This board provided space for up to 16
2708s, one of the most popular high density EPROMS at the time. 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) provided
addressing on any 4K boundary Additionally, each 4K block contains an
independent disable switch. This board also featured a wait state selection
switch to select zero or one wait state, provision for use of PHANTOM input (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.
One problem with the board is there is no Phantom OUTPUT line. So the
onboard ROMS cannot overlap with S-100 Bus RAM in the same memory space -- a
serious limitation. Most ROM boards like this pulled the Phantom line
low if addressed thereby inactivating any RAM board in that same address
space and thereby avoiding a bus conflict. If you use 8K,16K or 32K
RAM S-100 boards you may be OK, if you configure them correctly. Not so for
the later 64K RAM boards.
The manual for this board can be
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