>Several of the oscillator circuits are numerically unstable, and it was hard to get the >solution process to work without making it so slow as to be useless. We also had to figure >out how to emulate LM3900 op-amps more efficiently; they are a bit peculiar.
You also had the issue of the datasheet misprint in one of the parts books and had to search an earlier issue of a catalog to get exact values or connections iirc in order to begin creating components before working on the Midway game. This is what Derrick Renaud had predicted in his 2004 MW post when he gave his view of what issues might be involved of emulating non-cpu games back at the time. Fortunate that this work will enable other Midway 8080 racing games to have analog audio later.