RobertCX
Modern URDA SDK-86 variant
A really nice example of a modern URDA variant of the Intel SDK-86 board - this was made under license from Intel, and features some major improvements, namely 16K of RAM and simpler decode circuitry (no bipolar PROMs required). This has quadrupled the amount of RAM (compared to a fully upgraded Intel board), and more than halved the power consumption (less than 5W compared to around 12W). The old 2142 RAM chips and bipolar PROMs really chewed through some power, and the new 6264 static RAMs draw almost no power at all.
Unfortunately, however, the Intel serial and keypad monitors have been combined into a pair of EPROMs (rather than the four on the Intel board), meaning that it is no longer easy to swap them around to force a boot into the serial monitor. The green rubber keypad is also not overly ergonomic, mainly due to the tiny legends printed on it. However, it may be more reliable in the long term than the mechanical keyswitches used on the Intel boards.
It is also interesting to see that they have simply taken the original SDK-86 PCB layout, and cut and pasted in the new chips; they have different silk screen outlines and designations to the original chips. Some of the editing is a little sloppy; for example, the silk screen for some of the original decoupling capacitors is still present, even though the pads have been removed (in fact, the decoupling is a bit sparse in some places). The outline of the EPROM area also partially overlaps the RAM.
Modern URDA SDK-86 variant
A really nice example of a modern URDA variant of the Intel SDK-86 board - this was made under license from Intel, and features some major improvements, namely 16K of RAM and simpler decode circuitry (no bipolar PROMs required). This has quadrupled the amount of RAM (compared to a fully upgraded Intel board), and more than halved the power consumption (less than 5W compared to around 12W). The old 2142 RAM chips and bipolar PROMs really chewed through some power, and the new 6264 static RAMs draw almost no power at all.
Unfortunately, however, the Intel serial and keypad monitors have been combined into a pair of EPROMs (rather than the four on the Intel board), meaning that it is no longer easy to swap them around to force a boot into the serial monitor. The green rubber keypad is also not overly ergonomic, mainly due to the tiny legends printed on it. However, it may be more reliable in the long term than the mechanical keyswitches used on the Intel boards.
It is also interesting to see that they have simply taken the original SDK-86 PCB layout, and cut and pasted in the new chips; they have different silk screen outlines and designations to the original chips. Some of the editing is a little sloppy; for example, the silk screen for some of the original decoupling capacitors is still present, even though the pads have been removed (in fact, the decoupling is a bit sparse in some places). The outline of the EPROM area also partially overlaps the RAM.